How severe is CVE-2026-33526?

CVE-2026-33526 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-33526 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 9% (95th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-33526?

CVE-2026-33526 affects Squid-cache Squid. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-33526?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-33526 have an EU (EUVD) identifier?

Yes. CVE-2026-33526 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-16068.

When was CVE-2026-33526 published?

CVE-2026-33526 was published on 2026-03-26 and last updated on 2026-06-30.

CVE-2026-33526

CVE-2026-33526 is a high-severity vulnerability in Squid-cache Squid with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-416.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v4: 9.2
EPSS exploit prediction: 9% (95th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-16068
Weakness: CWE-416
Affected product: Squid-cache Squid
Published: 2026-03-26
Last modified: 2026-06-30

Description

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.

Frequently asked questions

What is CVE-2026-33526?: 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.
How severe is CVE-2026-33526?: CVE-2026-33526 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-33526 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 9% (95th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-33526?: CVE-2026-33526 affects Squid-cache Squid. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-33526?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-33526 have an EU (EUVD) identifier?: Yes. CVE-2026-33526 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-16068.
When was CVE-2026-33526 published?: CVE-2026-33526 was published on 2026-03-26 and last updated on 2026-06-30.

References

Affected products (1)

cpe:2.3:a:squid-cache:squid:*:*:*:*:*:*:*:*

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All CVEs affecting Squid-cache Squid →

Other CWE-416 (Use After Free) vulnerabilities

CVE-2026-13782 — Critical (CVSS 10.0): Use after free in Browser in Google Chrome prior to 150.0.7871.47 allowed a remote attacker who had compromised the…
CVE-2026-4725 — Critical (CVSS 10.0): Sandbox escape due to use-after-free in the Graphics: Canvas2D component. This vulnerability was fixed in Firefox 149…
CVE-2026-4688 — Critical (CVSS 10.0): Sandbox escape due to use-after-free in the Disability Access APIs component. This vulnerability was fixed in Firefox…
CVE-2025-24085 — Critical (CVSS 10.0): A use after free issue was addressed with improved memory management. This issue is fixed in iOS 18.3 and iPadOS 18.3,…
CVE-2024-43102 — Critical (CVSS 10.0): Concurrent removals of certain anonymous shared memory mappings by using the UMTX_SHM_DESTROY sub-request of…
CVE-2021-32495 — Critical (CVSS 10.0): Radare2 has a use-after-free vulnerability in pyc parser's get_none_object function. Attacker can read freed memory…

Browse all CWE-416 (Use After Free) vulnerabilities →

Threat intelligence

Threat-intel indicators referencing this CVE:

78.39.48.166 (ipv4-addr)
212.58.132.5 (ipv4-addr)
103.200.23.154 (ipv4-addr)
38.248.6.103 (ipv4-addr)
200.89.159.59 (ipv4-addr)
103.54.101.248 (ipv4-addr)
74.113.233.217 (ipv4-addr)
192.3.127.40 (ipv4-addr)