CVE-2026-32748

HighUpdated

Published: 26 March 2026

Published

26 March 2026

Modified

30 June 2026

KEV Added

—

Patch

25 March 2026

CVSS Score v4 8.7 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/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

EPSS Score 0.0273 84.3th percentile

Risk Priority 55 floored blend · peak EPSS

Summary

CVE-2026-32748 is a high-severity Improper Resource Locking (CWE-413) vulnerability in Squid-Cache Squid. Its CVSS base score is 8.7 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked in the top 15.7% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified are NIST 800-53 CM-7 (Least Functionality) and SC-5 (Denial-of-service Protection).

Deeper analysis

Squid, a widely deployed caching proxy for the Web, is affected by CVE-2026-32748 in all versions prior to 7.5. The root cause is a combination of premature resource release during the expected object lifetime and heap use-after-free conditions that manifest when the proxy processes ICP traffic. These memory-safety defects are tracked under CWE-413, CWE-416, and CWE-826 and produce a CVSS 4.0 score of 8.7 with high impact on availability.

A remote attacker who can send crafted ICP messages can trigger a reliable, repeatable denial-of-service condition against any Squid instance that has ICP support enabled via a non-zero icp_port setting. The attack succeeds even when icp_access rules are configured to restrict ICP queries, because the flaw occurs before access-control checks complete.

The official GitHub Security Advisory and the commit 703e07d25ca6fa11f52d20bf0bb879e22ab7481b confirm that the defects are resolved in Squid 7.5; operators are advised to upgrade rather than rely on network-level filtering. Mailing-list posts on oss-security reiterate that ICP must be disabled entirely if patching is delayed.

EPSS for the CVE rose sharply from a low baseline to a peak of 0.0180 on the disclosure date of 26 March 2026 before receding to its current value of 0.0021, indicating a transient but measurable increase in exploitation interest immediately after publication.

EU & UK References

🇪🇺 ENISA EUVD: EUVD-2026-16056

Vulnerability details

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.

CWE(s): CWE-413 CWE-416 CWE-826

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access

Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.

attack.mitre.org →

T1499.004 Application or System Exploitation Impact

Adversaries may exploit software vulnerabilities that can cause an application or system to crash and deny availability to users.

attack.mitre.org →

Why these techniques?

Remote exploitation of public-facing Squid proxy via crafted ICP traffic directly enables application/system exploitation resulting in service crash (DoS).

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0