Home/CVE/Squid is a caching proxy for the Web. In versions 6.3 and below, Squid is vulnerable to a heap buffer overflow and possi
CVE

CVE-2025-54574

Squid is a caching proxy for the Web. In versions 6.3 and below, Squid is vulnerable to a heap buffer overflow and possi

Squid is a caching proxy for the Web. In versions 6.3 and below, Squid is vulnerable to a heap buffer overflow and possible remote code execution attack when processing URN due to incorrect buffer management. This has been fixed in version 6.4.

To work around this issue, disable URN access permissions.

CRITICAL · CVSS 9.3 EPSS 0.0932
Schedule remediation
  • EPSS percentile: top 7% of all CVEs by exploitation likelihood
  • SSVC automatable: yes - attacks can be scripted at scale
  • CVSS base score ≥ 7.0
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-122Heap-based Buffer Overflow
CWE-787Out-of-bounds Write
▤

Affected Products & Versions

1
squid-cache squid< 6.4
▣

Scoring & Timeline

9.3
CRITICAL · CVSS v3.1 · security-advisories@github.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD01 Aug 2025 · 06:15 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:H
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
yes
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑

Vendor Advisories

9
rhsaRHSA-2024:0072Important
rhsaRHSA-2023:7668Important
rhsaRHSA-2024:1153Important
rhsaRHSA-2024:0771Important
rhsaRHSA-2024:0397Important
🔗

References & Sources

5
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://github.com/squid-cache/squid/commit/a27bf4b84da23594150c7a86a23435df0b35b988Patch
https://github.com/squid-cache/squid/releases/tag/SQUID_6_4Release Notes
https://github.com/squid-cache/squid/security/advisories/GHSA-w4gv-vw3f-29g3MitigationPatchVendor Advisory
http://www.openwall.com/lists/oss-security/2025/11/05/5
https://lists.debian.org/debian-lts-announce/2025/09/msg00027.html
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