CWE-204
AllowedObservable Response Discrepancy
Abstraction: Base · Status: Incomplete
The product provides different responses to incoming requests in a way that reveals internal state information to an unauthorized actor outside of the intended control sphere.
297 vulnerabilities reference this CWE, most recent first.
GHSA-6GCW-XCPF-VR88
Vulnerability from github – Published: 2024-09-19 18:30 – Updated: 2024-09-23 18:30A vulnerability in NetCat CMS allows an attacker to send a specially crafted http request that can be used to check whether a user exists in the system, which could be a basis for further attacks. This issue affects NetCat CMS v. 6.4.0.24126.2 and possibly others.
Apply patch from vendor https://netcat.ru/ https://netcat.ru/] . Versions 6.4.0.24248 and on have the patch.
{
"affected": [],
"aliases": [
"CVE-2024-8651"
],
"database_specific": {
"cwe_ids": [
"CWE-203",
"CWE-204"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-09-19T17:15:15Z",
"severity": "MODERATE"
},
"details": "A vulnerability in NetCat CMS allows an attacker to send a specially crafted http request that can be used to check whether a user exists in the system, which could be a basis for further attacks.\nThis issue affects NetCat CMS v. 6.4.0.24126.2 and possibly others.\n\nApply patch from vendor https://netcat.ru/ https://netcat.ru/] . Versions 6.4.0.24248 and on have the patch.",
"id": "GHSA-6gcw-xcpf-vr88",
"modified": "2024-09-23T18:30:34Z",
"published": "2024-09-19T18:30:52Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-8651"
},
{
"type": "WEB",
"url": "https://github.com/klsecservices/Advisories/blob/master/K-NetCat-2024-001.md"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/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-6GF6-3J9V-J983
Vulnerability from github – Published: 2025-07-03 12:34 – Updated: 2025-07-03 12:34For failed login attempts, the application returns different error messages depending on whether the login failed due to an incorrect password or a non-existing username. This allows an attacker to guess usernames until they find an existing one.
{
"affected": [],
"aliases": [
"CVE-2025-27451"
],
"database_specific": {
"cwe_ids": [
"CWE-203",
"CWE-204"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-07-03T12:15:22Z",
"severity": "MODERATE"
},
"details": "For failed login attempts, the application returns different error messages depending on whether the login failed due to an incorrect password or a non-existing username. This allows an attacker to guess usernames until they find an existing one.",
"id": "GHSA-6gf6-3j9v-j983",
"modified": "2025-07-03T12:34:58Z",
"published": "2025-07-03T12:34:58Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-27451"
},
{
"type": "WEB",
"url": "https://sick.com/psirt"
},
{
"type": "WEB",
"url": "https://www.cisa.gov/resources-tools/resources/ics-recommended-practices"
},
{
"type": "WEB",
"url": "https://www.endress.com"
},
{
"type": "WEB",
"url": "https://www.first.org/cvss/calculator/3.1"
},
{
"type": "WEB",
"url": "https://www.sick.com/.well-known/csaf/white/2025/sca-2025-0008.json"
},
{
"type": "WEB",
"url": "https://www.sick.com/.well-known/csaf/white/2025/sca-2025-0008.pdf"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-6HRX-7MGG-5CVP
Vulnerability from github – Published: 2025-05-22 15:34 – Updated: 2025-05-22 15:34Observable Response Discrepancy vulnerability in Tridium Niagara Framework on Windows, Linux, QNX, Tridium Niagara Enterprise Security on Windows, Linux, QNX allows Cryptanalysis. This issue affects Niagara Framework: before 4.14.2, before 4.15.1, before 4.10.11; Niagara Enterprise Security: before 4.14.2, before 4.15.1, before 4.10.11.Tridium recommends upgrading to Niagara Framework and Enterprise Security versions 4.14.2u2, 4.15.u1, or 4.10u.11.
{
"affected": [],
"aliases": [
"CVE-2025-3939"
],
"database_specific": {
"cwe_ids": [
"CWE-203",
"CWE-204"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-05-22T13:15:56Z",
"severity": "MODERATE"
},
"details": "Observable Response Discrepancy vulnerability in Tridium Niagara Framework on Windows, Linux, QNX, Tridium Niagara Enterprise Security on Windows, Linux, QNX allows Cryptanalysis. This issue affects Niagara Framework: before 4.14.2, before 4.15.1, before 4.10.11; Niagara Enterprise Security: before 4.14.2, before 4.15.1, before 4.10.11.Tridium recommends upgrading to Niagara Framework and Enterprise Security versions 4.14.2u2, 4.15.u1, or 4.10u.11.",
"id": "GHSA-6hrx-7mgg-5cvp",
"modified": "2025-05-22T15:34:49Z",
"published": "2025-05-22T15:34:49Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-3939"
},
{
"type": "WEB",
"url": "https://docs.niagara-community.com/category/tech_bull"
},
{
"type": "WEB",
"url": "https://honeywell.com/us/en/product-security#security-notices"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-6RJG-2HV4-XQ68
Vulnerability from github – Published: 2025-03-13 15:33 – Updated: 2025-03-19 21:30User Enumeration via Discrepancies in Error Messages in the Celk Sistemas Celk Saude v.3.1.252.1 password recovery functionality which allows a remote attacker to enumerate users through discrepancies in the responses.
{
"affected": [],
"aliases": [
"CVE-2024-55198"
],
"database_specific": {
"cwe_ids": [
"CWE-204"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-03-13T15:15:49Z",
"severity": "MODERATE"
},
"details": "User Enumeration via Discrepancies in Error Messages in the Celk Sistemas Celk Saude v.3.1.252.1 password recovery functionality which allows a remote attacker to enumerate users through discrepancies in the responses.",
"id": "GHSA-6rjg-2hv4-xq68",
"modified": "2025-03-19T21:30:46Z",
"published": "2025-03-13T15:33:00Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-55198"
},
{
"type": "WEB",
"url": "https://cheatsheetseries.owasp.org/cheatsheets/Authentication_Cheat_Sheet.html"
},
{
"type": "WEB",
"url": "https://github.com/gabriel-bri/vulnerability-research/tree/main/CVE-2024-55198"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-6X5V-CXPP-PC5X
Vulnerability from github – Published: 2023-03-21 06:30 – Updated: 2023-03-23 19:10Observable Response Discrepancy in GitHub repository answerdev/answer prior to 1.0.6.
{
"affected": [
{
"package": {
"ecosystem": "Go",
"name": "github.com/answerdev/answer"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "1.0.6"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2023-1540"
],
"database_specific": {
"cwe_ids": [
"CWE-203",
"CWE-204"
],
"github_reviewed": true,
"github_reviewed_at": "2023-03-21T22:32:37Z",
"nvd_published_at": "2023-03-21T05:15:00Z",
"severity": "MODERATE"
},
"details": "Observable Response Discrepancy in GitHub repository answerdev/answer prior to 1.0.6.",
"id": "GHSA-6x5v-cxpp-pc5x",
"modified": "2023-03-23T19:10:59Z",
"published": "2023-03-21T06:30:17Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-1540"
},
{
"type": "WEB",
"url": "https://github.com/answerdev/answer/commit/1de3ec27e50ba7389c9449c59e8ea3a37a908ee4"
},
{
"type": "PACKAGE",
"url": "https://github.com/answerdev/answer"
},
{
"type": "WEB",
"url": "https://huntr.dev/bounties/d8d6c259-a0f2-4209-a3b0-ecbf3eb092f4"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
"type": "CVSS_V3"
}
],
"summary": "Answer has Observable Response Discrepancy"
}
GHSA-742G-XJV2-HVH9
Vulnerability from github – Published: 2026-02-20 00:31 – Updated: 2026-02-24 18:31A user enumeration vulnerability exists in FormaLMS 4.1.18 and below in the password recovery functionality accessible via the /lostpwd endpoint. The application returns different error messages for valid and invalid usernames allowing an unauthenticated attacker to determine which usernames are registered in the system through observable response discrepancy.
{
"affected": [],
"aliases": [
"CVE-2026-26744"
],
"database_specific": {
"cwe_ids": [
"CWE-204"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-02-19T22:16:47Z",
"severity": "MODERATE"
},
"details": "A user enumeration vulnerability exists in FormaLMS 4.1.18 and below in the password recovery functionality accessible via the /lostpwd endpoint. The application returns different error messages for valid and invalid usernames allowing an unauthenticated attacker to determine which usernames are registered in the system through observable response discrepancy.",
"id": "GHSA-742g-xjv2-hvh9",
"modified": "2026-02-24T18:31:00Z",
"published": "2026-02-20T00:31:53Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-26744"
},
{
"type": "WEB",
"url": "https://github.com/formalms/formalms.git"
},
{
"type": "WEB",
"url": "https://github.com/lorenzobruno7/CVE-2026-26744"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-747X-F8JR-J7M2
Vulnerability from github – Published: 2024-07-04 15:30 – Updated: 2024-08-22 21:31Kaiten 57.128.8 allows remote attackers to enumerate user accounts via a crafted POST request, because a login response contains a user_email field only if the user account exists.
{
"affected": [],
"aliases": [
"CVE-2024-39211"
],
"database_specific": {
"cwe_ids": [
"CWE-204"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-07-04T13:15:10Z",
"severity": "MODERATE"
},
"details": "Kaiten 57.128.8 allows remote attackers to enumerate user accounts via a crafted POST request, because a login response contains a user_email field only if the user account exists.",
"id": "GHSA-747x-f8jr-j7m2",
"modified": "2024-08-22T21:31:28Z",
"published": "2024-07-04T15:30:40Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-39211"
},
{
"type": "WEB",
"url": "https://github.com/artemy-ccrsky/CVE-2024-39211"
},
{
"type": "WEB",
"url": "https://github.com/artemy-ccrsky/CVE-2024-39211/blob/main/CVE-2024-39211.sh"
},
{
"type": "WEB",
"url": "https://kaiten.ru"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-78G4-C5R9-6GH7
Vulnerability from github – Published: 2023-07-05 12:30 – Updated: 2024-04-04 05:23TN-5900 Series version 3.3 and prior versions is vulnearble to user enumeration vulnerability. The vulnerability may allow a remote attacker to determine whether a user is valid during password recovery through the web login page and enable a brute force attack with valid users.
{
"affected": [],
"aliases": [
"CVE-2023-3336"
],
"database_specific": {
"cwe_ids": [
"CWE-203",
"CWE-204"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-07-05T10:15:10Z",
"severity": "MODERATE"
},
"details": "TN-5900 Series version 3.3 and prior versions is vulnearble to user enumeration vulnerability. The vulnerability may allow a remote attacker to determine whether a user is valid during password recovery through the web login page and enable a brute force attack with valid users.\n\n",
"id": "GHSA-78g4-c5r9-6gh7",
"modified": "2024-04-04T05:23:23Z",
"published": "2023-07-05T12:30:15Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-3336"
},
{
"type": "WEB",
"url": "https://www.moxa.com/en/support/product-support/security-advisory/mpsa-230401-tn-5900-series-user-enumeration-vulnerability"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-7C2M-F7CW-58XJ
Vulnerability from github – Published: 2023-04-11 12:30 – Updated: 2023-04-11 12:30A vulnerability has been identified in Mendix Forgot Password (Mendix 7 compatible) (All versions < V3.7.1), Mendix Forgot Password (Mendix 8 compatible) (All versions < V4.1.1), Mendix Forgot Password (Mendix 9 compatible) (All versions < V5.1.1). The affected versions of the module contain an observable response discrepancy issue that could allow an attacker to retrieve sensitive information.
{
"affected": [],
"aliases": [
"CVE-2023-27464"
],
"database_specific": {
"cwe_ids": [
"CWE-203",
"CWE-204"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-04-11T10:15:00Z",
"severity": "MODERATE"
},
"details": "A vulnerability has been identified in Mendix Forgot Password (Mendix 7 compatible) (All versions \u003c V3.7.1), Mendix Forgot Password (Mendix 8 compatible) (All versions \u003c V4.1.1), Mendix Forgot Password (Mendix 9 compatible) (All versions \u003c V5.1.1). The affected versions of the module contain an observable response discrepancy issue that could allow an attacker to retrieve sensitive information.",
"id": "GHSA-7c2m-f7cw-58xj",
"modified": "2023-04-11T12:30:26Z",
"published": "2023-04-11T12:30:26Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-27464"
},
{
"type": "WEB",
"url": "https://cert-portal.siemens.com/productcert/pdf/ssa-699404.pdf"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-7H2G-P6HQ-VH75
Vulnerability from github – Published: 2026-04-01 18:36 – Updated: 2026-04-01 18:36The login mechanism of Sage DPW 2021_06_004 displays distinct responses for valid and invalid usernames, allowing enumeration of existing accounts in versions before 2021_06_000. On-premise administrators can toggle this behavior in newer versions.
{
"affected": [],
"aliases": [
"CVE-2025-67806"
],
"database_specific": {
"cwe_ids": [
"CWE-203",
"CWE-204"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-04-01T16:23:48Z",
"severity": "LOW"
},
"details": "The login mechanism of Sage DPW 2021_06_004 displays distinct responses for valid and invalid usernames, allowing enumeration of existing accounts in versions before 2021_06_000. On-premise administrators can toggle this behavior in newer versions.",
"id": "GHSA-7h2g-p6hq-vh75",
"modified": "2026-04-01T18:36:36Z",
"published": "2026-04-01T18:36:36Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-67806"
},
{
"type": "WEB",
"url": "https://pastebin.com/Tk4LgMG2"
},
{
"type": "WEB",
"url": "https://www.sagedpw.at"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N",
"type": "CVSS_V3"
}
]
}
Mitigation MIT-46
Strategy: Separation of Privilege
- Compartmentalize the system to have "safe" areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area.
- Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.
Mitigation MIT-39
- Ensure that error messages only contain minimal details that are useful to the intended audience and no one else. The messages need to strike the balance between being too cryptic (which can confuse users) or being too detailed (which may reveal more than intended). The messages should not reveal the methods that were used to determine the error. Attackers can use detailed information to refine or optimize their original attack, thereby increasing their chances of success.
- If errors must be captured in some detail, record them in log messages, but consider what could occur if the log messages can be viewed by attackers. Highly sensitive information such as passwords should never be saved to log files.
- Avoid inconsistent messaging that might accidentally tip off an attacker about internal state, such as whether a user account exists or not.
CAPEC-331: ICMP IP Total Length Field Probe
An adversary sends a UDP packet to a closed port on the target machine to solicit an IP Header's total length field value within the echoed 'Port Unreachable" error message. This type of behavior is useful for building a signature-base of operating system responses, particularly when error messages contain other types of information that is useful identifying specific operating system responses.
CAPEC-332: ICMP IP 'ID' Field Error Message Probe
An adversary sends a UDP datagram having an assigned value to its internet identification field (ID) to a closed port on a target to observe the manner in which this bit is echoed back in the ICMP error message. This allows the attacker to construct a fingerprint of specific OS behaviors.
CAPEC-541: Application Fingerprinting
An adversary engages in fingerprinting activities to determine the type or version of an application installed on a remote target.
CAPEC-580: System Footprinting
An adversary engages in active probing and exploration activities to determine security information about a remote target system. Often times adversaries will rely on remote applications that can be probed for system configurations.