CWE-331
AllowedInsufficient Entropy
Abstraction: Base · Status: Draft
The product uses an algorithm or scheme that produces insufficient entropy, leaving patterns or clusters of values that are more likely to occur than others.
207 vulnerabilities reference this CWE, most recent first.
GHSA-JGF7-8V7J-FWWH
Vulnerability from github – Published: 2026-02-03 15:30 – Updated: 2026-02-03 15:30Rapid7 Nexpose versions 6.4.50 and later are vulnerable to an insufficient entropy issue in the CredentialsKeyStorePassword.generateRandomPassword() method. When updating legacy keystore passwords, the application generates a new password with insufficient length (7-12 characters) and a static prefix 'p', resulting in a weak keyspace. An attacker with access to the nsc.ks file can brute-force this password using consumer-grade hardware to decrypt stored credentials.
{
"affected": [],
"aliases": [
"CVE-2026-1814"
],
"database_specific": {
"cwe_ids": [
"CWE-331"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-02-03T15:16:14Z",
"severity": "HIGH"
},
"details": "Rapid7 Nexpose versions 6.4.50 and later are vulnerable to an insufficient entropy issue in the CredentialsKeyStorePassword.generateRandomPassword() method. When updating legacy keystore passwords, the application generates a new password with insufficient length (7-12 characters) and a static prefix \u0027p\u0027, resulting in a weak keyspace. An attacker with access to the nsc.ks file can brute-force this password using consumer-grade hardware to decrypt stored credentials.",
"id": "GHSA-jgf7-8v7j-fwwh",
"modified": "2026-02-03T15:30:24Z",
"published": "2026-02-03T15:30:24Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-1814"
},
{
"type": "WEB",
"url": "https://www.atredis.com/disclosure"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:H/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"type": "CVSS_V4"
}
]
}
GHSA-JQP9-HWJJ-P328
Vulnerability from github – Published: 2022-05-14 00:56 – Updated: 2022-05-14 00:56It was discovered that libICE before 1.0.9-8 used a weak entropy to generate keys. A local attacker could potentially use this flaw for session hijacking using the information available from the process list.
{
"affected": [],
"aliases": [
"CVE-2017-2626"
],
"database_specific": {
"cwe_ids": [
"CWE-331"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2018-07-27T19:29:00Z",
"severity": "MODERATE"
},
"details": "It was discovered that libICE before 1.0.9-8 used a weak entropy to generate keys. A local attacker could potentially use this flaw for session hijacking using the information available from the process list.",
"id": "GHSA-jqp9-hwjj-p328",
"modified": "2022-05-14T00:56:29Z",
"published": "2022-05-14T00:56:29Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2017-2626"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2017:1865"
},
{
"type": "WEB",
"url": "https://access.redhat.com/security/cve/CVE-2017-2626"
},
{
"type": "WEB",
"url": "https://bugzilla.redhat.com/show_bug.cgi?id=1424992"
},
{
"type": "WEB",
"url": "https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2017-2626"
},
{
"type": "WEB",
"url": "https://cgit.freedesktop.org/xorg/lib/libICE/commit/?id=ff5e59f32255913bb1cdf51441b98c9107ae165b"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2019/11/msg00022.html"
},
{
"type": "WEB",
"url": "https://security.gentoo.org/glsa/201704-03"
},
{
"type": "WEB",
"url": "https://www.x41-dsec.de/lab/advisories/x41-2017-001-xorg"
},
{
"type": "WEB",
"url": "http://www.openwall.com/lists/oss-security/2019/07/14/3"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/96480"
},
{
"type": "WEB",
"url": "http://www.securitytracker.com/id/1037919"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-JQXQ-7F92-M7WW
Vulnerability from github – Published: 2025-03-11 00:31 – Updated: 2025-03-11 03:30Crypt::Random Perl package 1.05 through 1.55 may use rand() function, which is not cryptographically strong, for cryptographic functions.
Crypt::Random::rand 1.05 through 1.55 uses the rand() function. If the Provider is not specified and /dev/urandom or an Entropy Gathering Daemon (egd) service is not available Crypt::Random will default to use the insecure Crypt::Random::rand provider.
In particular, Windows versions of perl will encounter this issue by default.
{
"affected": [],
"aliases": [
"CVE-2025-1828"
],
"database_specific": {
"cwe_ids": [
"CWE-331",
"CWE-338"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-03-11T00:15:11Z",
"severity": "HIGH"
},
"details": "Crypt::Random Perl package 1.05 through 1.55 may use rand() function, which is not cryptographically strong, for cryptographic functions.\n\nCrypt::Random::rand 1.05 through 1.55 uses the rand() function. If the Provider is not specified and /dev/urandom or an Entropy Gathering Daemon (egd) service is not available Crypt::Random will default to use the insecure Crypt::Random::rand provider.\n\nIn particular, Windows versions of perl will encounter this issue by default.",
"id": "GHSA-jqxq-7f92-m7ww",
"modified": "2025-03-11T03:30:49Z",
"published": "2025-03-11T00:31:49Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-1828"
},
{
"type": "WEB",
"url": "https://github.com/perl-Crypt-OpenPGP/Crypt-Random/pull/1"
},
{
"type": "WEB",
"url": "https://github.com/perl-Crypt-OpenPGP/Crypt-Random/commit/1f8b29e9e89d8d083fd025152e76ec918136cc05"
},
{
"type": "WEB",
"url": "https://perldoc.perl.org/functions/rand"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-JRCG-6C8X-FF3H
Vulnerability from github – Published: 2024-10-23 18:33 – Updated: 2024-10-23 18:33A vulnerability in the session authentication functionality of the Remote Access SSL VPN feature of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to prevent users from authenticating.
This vulnerability is due to insufficient entropy in the authentication process. An attacker could exploit this vulnerability by determining the handle of an authenticating user and using it to terminate their authentication session. A successful exploit could allow the attacker to force a user to restart the authentication process, preventing a legitimate user from establishing remote access VPN sessions.
{
"affected": [],
"aliases": [
"CVE-2024-20331"
],
"database_specific": {
"cwe_ids": [
"CWE-330",
"CWE-331"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-10-23T17:15:17Z",
"severity": "MODERATE"
},
"details": "A vulnerability in the session authentication functionality of the Remote Access SSL VPN feature of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to prevent users from authenticating.\n\nThis vulnerability is due to insufficient entropy in the authentication process. An attacker could exploit this vulnerability by determining the handle of an authenticating user and using it to terminate their authentication session. A successful exploit could allow the attacker to force a user to restart the authentication process, preventing a legitimate user from establishing remote access VPN sessions.",
"id": "GHSA-jrcg-6c8x-ff3h",
"modified": "2024-10-23T18:33:08Z",
"published": "2024-10-23T18:33:08Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-20331"
},
{
"type": "WEB",
"url": "https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asa-vpn-nyH3fhp"
},
{
"type": "WEB",
"url": "https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmc-xss-M446vbEO"
},
{
"type": "WEB",
"url": "https://sec.cloudapps.cisco.com/security/center/viewErp.x?alertId=ERP-75300"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-JRGJ-6P6V-GF22
Vulnerability from github – Published: 2022-08-16 00:00 – Updated: 2022-08-19 00:00dproxy-nexgen (aka dproxy nexgen) uses a static UDP source port (selected randomly only at boot time) in upstream queries sent to DNS resolvers. This allows DNS cache poisoning because there is not enough entropy to prevent traffic injection attacks.
{
"affected": [],
"aliases": [
"CVE-2022-33989"
],
"database_specific": {
"cwe_ids": [
"CWE-331"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2022-08-15T13:15:00Z",
"severity": "MODERATE"
},
"details": "dproxy-nexgen (aka dproxy nexgen) uses a static UDP source port (selected randomly only at boot time) in upstream queries sent to DNS resolvers. This allows DNS cache poisoning because there is not enough entropy to prevent traffic injection attacks.",
"id": "GHSA-jrgj-6p6v-gf22",
"modified": "2022-08-19T00:00:22Z",
"published": "2022-08-16T00:00:25Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-33989"
},
{
"type": "WEB",
"url": "https://sourceforge.net/projects/dproxy"
},
{
"type": "WEB",
"url": "https://www.openwall.com/lists/oss-security/2022/08/14/3"
},
{
"type": "WEB",
"url": "https://www.usenix.org/conference/usenixsecurity22/presentation/jeitner"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-M22W-QPWR-JXRJ
Vulnerability from github – Published: 2022-05-13 01:14 – Updated: 2022-05-13 01:14QEMU, when built with the Pseudo Random Number Generator (PRNG) back-end support, allows local guest OS users to cause a denial of service (process crash) via an entropy request, which triggers arbitrary stack based allocation and memory corruption.
{
"affected": [],
"aliases": [
"CVE-2016-2858"
],
"database_specific": {
"cwe_ids": [
"CWE-331"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2016-04-07T19:59:00Z",
"severity": "MODERATE"
},
"details": "QEMU, when built with the Pseudo Random Number Generator (PRNG) back-end support, allows local guest OS users to cause a denial of service (process crash) via an entropy request, which triggers arbitrary stack based allocation and memory corruption.",
"id": "GHSA-m22w-qpwr-jxrj",
"modified": "2022-05-13T01:14:34Z",
"published": "2022-05-13T01:14:34Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2016-2858"
},
{
"type": "WEB",
"url": "https://bugzilla.redhat.com/show_bug.cgi?id=1314676"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2018/11/msg00038.html"
},
{
"type": "WEB",
"url": "https://security.gentoo.org/glsa/201604-01"
},
{
"type": "WEB",
"url": "http://git.qemu.org/?p=qemu.git%3Ba=commit%3Bh=60253ed1e6ec6d8e5ef2efe7bf755f475dce9956"
},
{
"type": "WEB",
"url": "http://git.qemu.org/?p=qemu.git;a=commit;h=60253ed1e6ec6d8e5ef2efe7bf755f475dce9956"
},
{
"type": "WEB",
"url": "http://www.openwall.com/lists/oss-security/2016/03/04/1"
},
{
"type": "WEB",
"url": "http://www.openwall.com/lists/oss-security/2016/03/07/4"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/84134"
},
{
"type": "WEB",
"url": "http://www.ubuntu.com/usn/USN-2974-1"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-M24W-QFH4-J8M4
Vulnerability from github – Published: 2022-06-15 00:00 – Updated: 2024-07-09 12:30A vulnerability has been identified in SINEMA Remote Connect Server (All versions < V3.1). An attacker in machine-in-the-middle could obtain plaintext secret values by observing length differences during a series of guesses in which a string in an HTTP request URL potentially matches an unknown string in an HTTP response body, aka a "BREACH" attack.
{
"affected": [],
"aliases": [
"CVE-2022-27221"
],
"database_specific": {
"cwe_ids": [
"CWE-203",
"CWE-331"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2022-06-14T10:15:00Z",
"severity": "MODERATE"
},
"details": "A vulnerability has been identified in SINEMA Remote Connect Server (All versions \u003c V3.1). An attacker in machine-in-the-middle could obtain plaintext secret values by observing length differences during a series of guesses in which a string in an HTTP request URL potentially matches an unknown string in an HTTP response body, aka a \"BREACH\" attack.",
"id": "GHSA-m24w-qfh4-j8m4",
"modified": "2024-07-09T12:30:54Z",
"published": "2022-06-15T00:00:28Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-27221"
},
{
"type": "WEB",
"url": "https://cert-portal.siemens.com/productcert/html/ssa-484086.html"
},
{
"type": "WEB",
"url": "https://cert-portal.siemens.com/productcert/pdf/ssa-484086.pdf"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-M7X8-4574-HXW6
Vulnerability from github – Published: 2022-08-09 00:00 – Updated: 2022-08-13 00:00websda.c in GoAhead WebServer 2.1.8 has insufficient nonce entropy because the nonce calculation relies on the hardcoded onceuponatimeinparadise value, which does not follow the secret-data guideline for HTTP Digest Access Authentication in RFC 7616 section 3.3 (or RFC 2617 section 3.2.1). NOTE: 2.1.8 is a version from 2003; however, the affected websda.c code appears in multiple derivative works that may be used in 2021. Recent GoAhead software is unaffected.
{
"affected": [],
"aliases": [
"CVE-2021-41615"
],
"database_specific": {
"cwe_ids": [
"CWE-331"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2022-08-08T19:15:00Z",
"severity": "CRITICAL"
},
"details": "websda.c in GoAhead WebServer 2.1.8 has insufficient nonce entropy because the nonce calculation relies on the hardcoded onceuponatimeinparadise value, which does not follow the secret-data guideline for HTTP Digest Access Authentication in RFC 7616 section 3.3 (or RFC 2617 section 3.2.1). NOTE: 2.1.8 is a version from 2003; however, the affected websda.c code appears in multiple derivative works that may be used in 2021. Recent GoAhead software is unaffected.",
"id": "GHSA-m7x8-4574-hxw6",
"modified": "2022-08-13T00:00:52Z",
"published": "2022-08-09T00:00:21Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-41615"
},
{
"type": "WEB",
"url": "https://devel.rtems.org/browser/rtems/cpukit/httpd/websda.c?rev=c1427d2758079f0e9dd6a8de1662d78e0d6bc4ca"
},
{
"type": "WEB",
"url": "https://github.com/trenta3/goahead-versions/blob/master/2.1.8/230165webs218.tar.gz?raw=true"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-M8VJ-88WQ-7CHF
Vulnerability from github – Published: 2023-12-21 21:30 – Updated: 2023-12-21 21:30An insufficient entropy vulnerability was identified in GitHub Enterprise Server (GHES) that allowed an attacker to brute force a user invitation to the GHES Management Console. To exploit this vulnerability, an attacker would need knowledge that a user invitation was pending. This vulnerability affected all versions of GitHub Enterprise Server since 3.8 and was fixed in version 3.8.12, 3.9.7, 3.10.4, and 3.11.1. This vulnerability was reported via the GitHub Bug Bounty program.
{
"affected": [],
"aliases": [
"CVE-2023-46648"
],
"database_specific": {
"cwe_ids": [
"CWE-331"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-12-21T21:15:09Z",
"severity": "HIGH"
},
"details": "An insufficient entropy vulnerability was identified in GitHub Enterprise Server (GHES) that allowed an attacker to brute force a user invitation to the GHES Management Console. To exploit this vulnerability, an attacker would need knowledge that a user invitation was pending. This vulnerability affected all versions of GitHub Enterprise Server since 3.8 and was fixed in version 3.8.12, 3.9.7, 3.10.4, and 3.11.1. This vulnerability was reported via the GitHub Bug Bounty program.\n",
"id": "GHSA-m8vj-88wq-7chf",
"modified": "2023-12-21T21:30:31Z",
"published": "2023-12-21T21:30:31Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-46648"
},
{
"type": "WEB",
"url": "https://docs.github.com/en/enterprise-server@3.10/admin/release-notes#3.10.4"
},
{
"type": "WEB",
"url": "https://docs.github.com/en/enterprise-server@3.11/admin/release-notes#3.11.1"
},
{
"type": "WEB",
"url": "https://docs.github.com/en/enterprise-server@3.8/admin/release-notes#3.8.12"
},
{
"type": "WEB",
"url": "https://docs.github.com/en/enterprise-server@3.9/admin/release-notes#3.9.7"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-M98W-CQP3-QCQR
Vulnerability from github – Published: 2025-12-08 17:57 – Updated: 2025-12-12 16:30Summary
Critical security vulnerabilities exist in both the UUIDv4() and UUID() functions of the github.com/gofiber/utils package. When the system's cryptographic random number generator (crypto/rand) fails, both functions silently fall back to returning predictable UUID values, the zero UUID "00000000-0000-0000-0000-000000000000". This compromises the security of all Fiber applications using these functions for security-critical operations on Go versions prior to 1.24.
Both functions are vulnerable to the same root cause (crypto/rand failure):
UUIDv4(): Indirect vulnerability throughuuid.NewRandom()→crypto/rand.Read()→ fallback toUUID()UUID(): Direct vulnerability throughcrypto/rand.Read(uuidSeed[:])→ silent zero UUID return
Note: Go 1.24 and later panics on
crypto/randRead()failures, mitigating this vulnerability. Applications running on Go 1.24+ are not affected by the silent fallback behavior.
Vulnerability Details
Affected Functions
- Package:
github.com/gofiber/utils - Functions:
UUIDv4()andUUID() - Return Type:
string(both functions) - Locations:
common.go:93-99(UUIDv4),common.go:60-89(UUID)
Technical Description
The vulnerability occurs through two related but distinct failure paths, both ultimately caused by crypto/rand.Read() failures on Go < 1.24:
Primary Path: UUIDv4() Vulnerability
UUIDv4()callsgoogle/uuid.NewRandom()which internally usescrypto/rand.Read()- If
uuid.NewRandom()fails,UUIDv4()falls back to the internalUUID()function - No error is returned to the application - silent security failure occurs
Secondary Path: UUID() Vulnerability
UUID()directly callscrypto/rand.Read(uuidSeed[:])to seed its internal state- If seeding fails,
UUID()silently fails and returns the zero UUID"00000000-0000-0000-0000-000000000000" - Applications receive predictable UUIDs with no indication of the security failure
Code Analysis
UUIDv4() Vulnerability Path
func UUIDv4() string {
token, err := uuid.NewRandom() // Uses crypto/rand.Read() internally
if err != nil {
return UUID() // Dangerous fallback - no error returned to application
}
return token.String()
}
UUID() Vulnerability Path
func UUID() string {
uuidSetup.Do(func() {
if _, err := rand.Read(uuidSeed[:]); err != nil { // Direct crypto/rand.Read() call
return // Silent failure - no seeding, uuidCounter remains 0
}
uuidCounter = binary.LittleEndian.Uint64(uuidSeed[:8])
})
if atomic.LoadUint64(&uuidCounter) <= 0 {
return "00000000-0000-0000-0000-000000000000" // Zero UUID returned silently
}
// ... generate UUID from counter
}
Root Cause: Both vulnerabilities stem from crypto/rand.Read() failures, occurring through different code paths with the same dangerous silent fallback behavior.
Security Impact
Severity: CRITICAL
This issue is especially severe because many Fiber middleware packages (session, CSRF, auth, rate-limit, request-ID, etc.) default to utils.UUIDv4() for generating security-sensitive identifiers. A failure in crypto/rand would cause every generated identifier across the entire application to collapse to a single predictable value (the zero UUID), resulting in:
- Session fixation / universal session hijack
- CSRF token predictability and bypass
- Authentication token replay
- Global identifier collisions leading to severe application breakage
- Potential application-wide DoS due to every request using the same “unique” key, causing cache overwrites, session stomping, corrupted internal maps, and loss of isolation across all users
Attack Scenario
While entropy exhaustion is extremely rare on modern Linux systems, RNG access failures (e.g., restricted /dev/random or /dev/urandom access, broken container environments, sandbox restrictions, misconfigured VMs, or FIPS-mode RNG failures) are realistic. In these scenarios on Go < 1.24, crypto/rand may return errors immediately — triggering the vulnerable fallback paths.
On Go 1.24+, crypto/rand Read() panics on failure, mitigating the silent-zero fallback issue.
Proof of Concept
uuid.NewRandom()fails (indirectcrypto/rand.Read()failure)UUIDv4()callsUUID()as fallback with no error returnedUUID()seeding fails directly viacrypto/rand.Read(uuidSeed[:])- Zero UUID
"00000000-0000-0000-0000-000000000000"is returned silently - No error is propagated to the application from either function
Affected Versions
- All versions of
github.com/gofiber/utilscontaining theUUIDv4()orUUID()functions - Applications using Fiber middleware that depend on
UUIDv4()orUUIDfor security - Only applicable to Go < 1.24; Go 1.24+ panics/block on
crypto/randRead()failures and is not affected
Mitigation
Immediate Workaround
Replace usage of utils.UUIDv4() with uuid.New() or wait for fix:
sessionID := uuid.New()
Recommended Fix
Modify utils.UUIDv4() and utils.UUID() to fail explicitly when cryptographic randomness is unavailable:
func UUIDv4() string {
token, err := uuid.NewRandom()
if err != nil {
panic(fmt.Sprintf("utils: failed to generate secure UUID: %v", err))
}
return token.String()
}
func UUID() string {
uuidSetup.Do(func() {
if _, err := rand.Read(uuidSeed[:]); err != nil {
panic(fmt.Sprintf("utils: failed to seed UUID generator: %v", err))
}
uuidCounter = binary.LittleEndian.Uint64(uuidSeed[:8])
})
if atomic.LoadUint64(&uuidCounter) <= 0 {
panic("utils: UUID generator not properly seeded")
}
// ... generate UUID from counter
}
Detection
Applications can detect if they're affected by:
- Checking if they use
github.com/gofiber/utils - Searching for
UUIDv4()andUUID()usage in security-critical code paths - Reviewing Fiber middleware configurations that rely on defaults of
UUIDv4()for security identifiers
References
- Package Repository: https://github.com/gofiber/utils
- Fiber Framework: https://github.com/gofiber/fiber
- Google UUID Library: https://github.com/google/uuid
- Golang
crypto/randbehavior changes: golang/go#66821, Go 1.25.5 source
Contact
Reported by: @sixcolors
Classification
- OWASP: A02:2021 - Cryptographic Failures
- Impact: Complete compromise of application security model on Go < 1.24
- Exploitability: Medium (requires entropy failure)
- Scope: All Fiber applications using affected middleware on Go < 1.24
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c 2.0.0-rc.3.0.20251205210924-6c6cf047032b"
},
"package": {
"ecosystem": "Go",
"name": "github.com/gofiber/utils/v2"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "2.0.0-rc.4"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 1.1.0"
},
"package": {
"ecosystem": "Go",
"name": "github.com/gofiber/utils"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "1.2.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2025-66565"
],
"database_specific": {
"cwe_ids": [
"CWE-252",
"CWE-331",
"CWE-338"
],
"github_reviewed": true,
"github_reviewed_at": "2025-12-08T17:57:26Z",
"nvd_published_at": "2025-12-09T16:18:21Z",
"severity": "CRITICAL"
},
"details": "## Summary\n\nCritical security vulnerabilities exist in both the `UUIDv4()` and `UUID()` functions of the `github.com/gofiber/utils` package. When the system\u0027s cryptographic random number generator (`crypto/rand`) fails, both functions silently fall back to returning predictable UUID values, the zero UUID `\"00000000-0000-0000-0000-000000000000\"`. This compromises the security of all Fiber applications using these functions for security-critical operations on **Go versions prior to 1.24**.\n\n**Both functions are vulnerable to the same root cause (`crypto/rand` failure):**\n\n* `UUIDv4()`: Indirect vulnerability through `uuid.NewRandom()` \u2192 `crypto/rand.Read()` \u2192 fallback to `UUID()`\n* `UUID()`: Direct vulnerability through `crypto/rand.Read(uuidSeed[:])` \u2192 silent zero UUID return\n\n\u003e **Note:** Go 1.24 and later panics on `crypto/rand` `Read()` failures, mitigating this vulnerability. Applications running on Go 1.24+ are not affected by the silent fallback behavior.\n\n---\n\n## Vulnerability Details\n\n### Affected Functions\n\n* **Package**: `github.com/gofiber/utils`\n* **Functions**: `UUIDv4()` and `UUID()`\n* **Return Type**: `string` (both functions)\n* **Locations**: `common.go:93-99` (UUIDv4), `common.go:60-89` (UUID)\n\n### Technical Description\n\nThe vulnerability occurs through two related but distinct failure paths, both ultimately caused by `crypto/rand.Read()` failures on Go \u003c 1.24:\n\n#### Primary Path: UUIDv4() Vulnerability\n\n1. `UUIDv4()` calls `google/uuid.NewRandom()` which internally uses `crypto/rand.Read()`\n2. If `uuid.NewRandom()` fails, `UUIDv4()` falls back to the internal `UUID()` function\n3. **No error is returned to the application** - silent security failure occurs\n\n#### Secondary Path: UUID() Vulnerability\n\n1. `UUID()` directly calls `crypto/rand.Read(uuidSeed[:])` to seed its internal state\n2. If seeding fails, `UUID()` **silently fails** and returns the zero UUID `\"00000000-0000-0000-0000-000000000000\"`\n3. Applications receive predictable UUIDs with no indication of the security failure\n\n---\n\n### Code Analysis\n\n#### UUIDv4() Vulnerability Path\n\n```go\nfunc UUIDv4() string {\n\ttoken, err := uuid.NewRandom() // Uses crypto/rand.Read() internally\n\tif err != nil {\n\t\treturn UUID() // Dangerous fallback - no error returned to application\n\t}\n\treturn token.String()\n}\n```\n\n#### UUID() Vulnerability Path\n\n```go\nfunc UUID() string {\n\tuuidSetup.Do(func() {\n\t\tif _, err := rand.Read(uuidSeed[:]); err != nil { // Direct crypto/rand.Read() call\n\t\t\treturn // Silent failure - no seeding, uuidCounter remains 0\n\t\t}\n\t\tuuidCounter = binary.LittleEndian.Uint64(uuidSeed[:8])\n\t})\n\tif atomic.LoadUint64(\u0026uuidCounter) \u003c= 0 {\n\t\treturn \"00000000-0000-0000-0000-000000000000\" // Zero UUID returned silently\n\t}\n\t// ... generate UUID from counter\n}\n```\n\n**Root Cause:** Both vulnerabilities stem from `crypto/rand.Read()` failures, occurring through different code paths with the same dangerous silent fallback behavior.\n\n---\n\n## Security Impact\n\n### Severity: CRITICAL\n\nThis issue is especially severe because many Fiber middleware packages (session, CSRF, auth, rate-limit, request-ID, etc.) default to `utils.UUIDv4()` for generating security-sensitive identifiers. A failure in `crypto/rand` would cause **every generated identifier across the entire application** to collapse to a single predictable value (the zero UUID), resulting in:\n\n* **Session fixation / universal session hijack**\n* **CSRF token predictability and bypass**\n* **Authentication token replay**\n* **Global identifier collisions leading to severe application breakage**\n* **Potential application-wide DoS** due to every request using the same \u201cunique\u201d key, causing cache overwrites, session stomping, corrupted internal maps, and loss of isolation across all users\n\n---\n\n### Attack Scenario\n\nWhile **entropy exhaustion is extremely rare on modern Linux systems**, *RNG access failures* (e.g., restricted `/dev/random` or `/dev/urandom` access, broken container environments, sandbox restrictions, misconfigured VMs, or FIPS-mode RNG failures) are realistic. In these scenarios on **Go \u003c 1.24**, `crypto/rand` may return errors immediately \u2014 triggering the vulnerable fallback paths.\n\nOn **Go 1.24+**, `crypto/rand` `Read()` panics on failure, mitigating the silent-zero fallback issue.\n\n---\n\n### Proof of Concept\n\n1. `uuid.NewRandom()` fails (indirect `crypto/rand.Read()` failure)\n2. `UUIDv4()` calls `UUID()` as fallback with no error returned\n3. `UUID()` seeding fails directly via `crypto/rand.Read(uuidSeed[:])`\n4. Zero UUID `\"00000000-0000-0000-0000-000000000000\"` is returned silently\n5. No error is propagated to the application from either function\n\n---\n\n## Affected Versions\n\n* All versions of `github.com/gofiber/utils` containing the `UUIDv4()` or `UUID()` functions\n* Applications using Fiber middleware that depend on `UUIDv4()` or `UUID` for security\n* **Only applicable to Go \u003c 1.24**; Go 1.24+ panics/block on `crypto/rand` `Read()` failures and is not affected\n\n---\n\n## Mitigation\n\n### Immediate Workaround\n\nReplace usage of `utils.UUIDv4()` with `uuid.New()` or wait for fix:\n\n```go\nsessionID := uuid.New()\n```\n\n### Recommended Fix\n\nModify `utils.UUIDv4()` and `utils.UUID()` to fail explicitly when cryptographic randomness is unavailable:\n\n```go\nfunc UUIDv4() string {\n\ttoken, err := uuid.NewRandom()\n\tif err != nil {\n\t\tpanic(fmt.Sprintf(\"utils: failed to generate secure UUID: %v\", err))\n\t}\n\treturn token.String()\n}\n\nfunc UUID() string {\n uuidSetup.Do(func() {\n if _, err := rand.Read(uuidSeed[:]); err != nil {\n panic(fmt.Sprintf(\"utils: failed to seed UUID generator: %v\", err))\n }\n uuidCounter = binary.LittleEndian.Uint64(uuidSeed[:8])\n })\n if atomic.LoadUint64(\u0026uuidCounter) \u003c= 0 {\n panic(\"utils: UUID generator not properly seeded\")\n }\n // ... generate UUID from counter\n}\n```\n\n---\n\n## Detection\n\nApplications can detect if they\u0027re affected by:\n\n1. Checking if they use `github.com/gofiber/utils`\n2. Searching for `UUIDv4()` and `UUID()` usage in security-critical code paths\n3. Reviewing Fiber middleware configurations that rely on defaults of `UUIDv4()` for security identifiers\n\n---\n\n## References\n\n* **Package Repository**: [https://github.com/gofiber/utils](https://github.com/gofiber/utils)\n* **Fiber Framework**: [https://github.com/gofiber/fiber](https://github.com/gofiber/fiber)\n* **Google UUID Library**: [https://github.com/google/uuid](https://github.com/google/uuid)\n* Golang `crypto/rand` behavior changes: [golang/go#66821](https://github.com/golang/go/issues/66821), [Go 1.25.5 source](https://cs.opensource.google/go/go/+/refs/tags/go1.25.5:src/crypto/rand/rand.go;l=80)\n\n---\n\n## Contact\n\nReported by: [@sixcolors](https://github.com/sixcolors)\n\n---\n\n## Classification\n\n* **OWASP**: A02:2021 - Cryptographic Failures\n* **Impact**: Complete compromise of application security model on Go \u003c 1.24\n* **Exploitability**: Medium (requires entropy failure)\n* **Scope**: All Fiber applications using affected middleware on Go \u003c 1.24",
"id": "GHSA-m98w-cqp3-qcqr",
"modified": "2025-12-12T16:30:26Z",
"published": "2025-12-08T17:57:26Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/gofiber/utils/security/advisories/GHSA-m98w-cqp3-qcqr"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-66565"
},
{
"type": "WEB",
"url": "https://github.com/gofiber/utils/commit/6c6cf047032b9c8dff43d29f990b4b10e9b02d47"
},
{
"type": "PACKAGE",
"url": "https://github.com/gofiber/utils"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Fiber Utils UUIDv4 and UUID Silent Fallback to Predictable Values"
}
Mitigation
Determine the necessary entropy to adequately provide for randomness and predictability. This can be achieved by increasing the number of bits of objects such as keys and seeds.
CAPEC-59: Session Credential Falsification through Prediction
This attack targets predictable session ID in order to gain privileges. The attacker can predict the session ID used during a transaction to perform spoofing and session hijacking.