Vulnerability-Lookup

RHSA-2026:6301

Vulnerability from csaf_redhat - Published: 2026-03-31 20:09 - Updated: 2026-04-04 00:08

Summary

Red Hat Security Advisory: squid security update

Severity

Important

Notes

Topic: An update for squid is now available for Red Hat Enterprise Linux 9. Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.

Details: Squid is a high-performance proxy caching server for web clients, supporting FTP, and HTTP data objects. Security Fix(es): * squid: Squid: Denial of Service via heap Use-After-Free vulnerability in ICP handling (CVE-2026-33526) * Squid: Squid: Denial of Service via crafted ICP traffic (CVE-2026-32748) For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Terms of Use: This content is licensed under the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/). If you distribute this content, or a modified version of it, you must provide attribution to Red Hat Inc. and provide a link to the original.

CVE-2026-32748

A flaw was found in Squid. A remote attacker can exploit this vulnerability by sending specially crafted ICP (Internet Cache Protocol) traffic. This can lead to a Denial of Service (DoS) due to premature resource release and use-after-free vulnerabilities. This attack is possible in Squid deployments with explicitly enabled ICP support.

7.5 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CWE-826 - Premature Release of Resource During Expected Lifetime

Vendor Fix For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 https://access.redhat.com/errata/RHSA-2026:6301

Workaround To mitigate this issue, ensure that ICP support is not explicitly enabled in the Squid configuration. This can be achieved by commenting out or setting `icp_port` to `0` in the `squid.conf` file. After modifying the configuration, the Squid service must be reloaded or restarted for the changes to take effect. Example: ``` # icp_port 3130 ``` or ``` icp_port 0 ``` Warning: Reloading or restarting the Squid service may temporarily interrupt proxy services.

CVE-2026-33526

A flaw was found in Squid. A remote attacker can exploit a heap Use-After-Free vulnerability when handling ICP (Internet Cache Protocol) traffic. This allows them to perform a reliable and repeatable Denial of Service (DoS) attack, making the Squid service unavailable. This attack is limited to deployments where ICP support is explicitly enabled.

7.5 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CWE-825 - Expired Pointer Dereference

Workaround To mitigate this issue, disable ICP support in Squid by ensuring that `icp_port` is set to `0` in the `squid.conf` configuration file. This will prevent Squid from processing ICP traffic and eliminate the attack vector. After modifying the configuration, the Squid service must be restarted for the changes to take effect.

References

URL

Category

	https://access.redhat.com/errata/RHSA-2026:6301	self
	https://access.redhat.com/security/updates/classi…	external
	https://bugzilla.redhat.com/show_bug.cgi?id=2451574	external
	https://bugzilla.redhat.com/show_bug.cgi?id=2451577	external
	https://security.access.redhat.com/data/csaf/v2/a…	self
	https://access.redhat.com/security/cve/CVE-2026-32748	self
	https://bugzilla.redhat.com/show_bug.cgi?id=2451577	external
	https://www.cve.org/CVERecord?id=CVE-2026-32748	external
	https://nvd.nist.gov/vuln/detail/CVE-2026-32748	external
	http://www.openwall.com/lists/oss-security/2026/03/25/3	external
	https://github.com/squid-cache/squid/commit/703e0…	external
	https://github.com/squid-cache/squid/security/adv…	external
	https://access.redhat.com/security/cve/CVE-2026-33526	self
	https://bugzilla.redhat.com/show_bug.cgi?id=2451574	external
	https://www.cve.org/CVERecord?id=CVE-2026-33526	external
	https://nvd.nist.gov/vuln/detail/CVE-2026-33526	external
	http://www.openwall.com/lists/oss-security/2026/03/25/2	external
	https://github.com/squid-cache/squid/commit/8a7d4…	external
	https://github.com/squid-cache/squid/security/adv…	external

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          "title": "Vulnerability summary"
        },
        {
          "category": "other",
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          "title": "Statement"
        },
        {
          "category": "general",
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}

CVE-2026-32748 (GCVE-0-2026-32748)

Vulnerability from cvelistv5 – Published: 2026-03-26 00:11 – Updated: 2026-03-26 15:02

Title

Squid has Denial of Service in ICP Response handling

Summary

Squid is a caching proxy for the Web. Prior to version 7.5, due to premature release of resource during expected lifetime and heap Use-After-Free bugs, Squid is vulnerable to Denial of Service when handling ICP traffic. This problem allows a remote attacker to perform a reliable and repeatable Denial of Service attack against the Squid service using ICP protocol. This attack is limited to Squid deployments that explicitly enable ICP support (i.e. configure non-zero `icp_port`). This problem _cannot_ be mitigated by denying ICP queries using `icp_access` rules. This bug is fixed in Squid version 7.5.

Severity ?

8.7 (High)


                        
                          CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L

CWE

CWE-413 - Improper Resource Locking
CWE-416 - Use After Free
CWE-826 - Premature Release of Resource During Expected Lifetime

Assigner

GitHub_M

References

URL

	Vendor	Product	Version
	squid-cache	squid	Affected: < 7.5

CVE-2026-33526 (GCVE-0-2026-33526)

Vulnerability from cvelistv5 – Published: 2026-03-26 00:16 – Updated: 2026-03-26 18:20

Title

Squid vulnerable to Denial of Service in ICP Request handling

Summary

Squid is a caching proxy for the Web. Prior to version 7.5, due to heap Use-After-Free, Squid is vulnerable to Denial of Service when handling ICP traffic. This problem allows a remote attacker to perform a reliable and repeatable Denial of Service attack against the Squid service using ICP protocol. This attack is limited to Squid deployments that explicitly enable ICP support (i.e. configure non-zero `icp_port`). This problem _cannot_ be mitigated by denying ICP queries using `icp_access` rules. Version 7.5 contains a patch.

Severity ?

9.2 (Critical)


                        
                          CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H

CWE

CWE-416 - Use After Free
CWE-826 - Premature Release of Resource During Expected Lifetime

Assigner

GitHub_M

References

URL

	Vendor	Product	Version
	squid-cache	squid	Affected: < 7.5

Sightings

Author	Source	Type	Date

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

RHSA-2026:6301

CVE-2026-32748 (GCVE-0-2026-32748)

CVE-2026-33526 (GCVE-0-2026-33526)

Tags

Sightings

Nomenclature