CVE-2025-54574 | Squid's URN Handling can lead to Buffer Overflow

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.

Published: 2025-08-01 Last update: 2025-11-05 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2025-54574 is rated High Risk (75.7/100): CVSS Critical severity, with high exploitation likelihood (EPSS 19.87%, 96th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. EPSS rose +10.55% over the last day, indicating growing attacker interest. High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2025-54574

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-11 9.32% 19.87% +10.55%
2 2026-05-28 4.99% 9.32% +4.33%
3 2026-05-24 — 4.99% —

Full EPSS history (28 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-54574

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.3 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 4.7 [email protected]
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]

Weakness enumeration for CVE-2025-54574

OS Trackers for CVE-2025-54574

vendor priority summary link
alpine critical CVE-2025-54574: 1 source package rows (squid); 55 state rows across 5 repos (3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 0, open 55. https://security.alpinelinux.org/vuln/CVE-2025-54574
debian not yet assigned CVE-2025-54574 not yet assigned priority: Debian including 1 source packages (squid), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2025-54574
redhat high — https://access.redhat.com/security/cve/CVE-2025-54574
suse high CVE-2025-54574 severity important: SUSE including 1 source package names (squid), 27 product×package rows across 27 product lines (SLES-LTSS-TERADATA 15 SP2, SUSE Linux Enterprise High Performance Computing 15 SP3-LTSS, … (27 product lines)): Will Not Fix 24, Known Not Affected 3. https://www.suse.com/security/cve/CVE-2025-54574/
ubuntu medium CVE-2025-54574 medium priority: Ubuntu including 2 source packages (squid, squid3), 13 status rows across 8 suites (bionic, focal, jammy, noble, plucky, questing, upstream, xenial): DNE 4, needs-triage 3, not-affected 3, released 3. https://ubuntu.com/security/CVE-2025-54574

Affected software / configurations for CVE-2025-54574

Vendor Product Version Raw CPE
squid-cache squid < 6.4 cpe:2.3:a:squid-cache:squid:*:*:*:*:*:*:*:*

References for CVE-2025-54574

cvelogic Threat Intelligence