# CVE-2026-33526: Squid vulnerable to Denial of Service in ICP Request handling

> Remote attackers can cause a denial of service in Squid via ICP traffic if ICP support is explicitly enabled.

- **Severity:** Critical 9.2 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 26 Mar 2026
- **Updated:** 15 Jul 2026
- **Also known as:** AZL-80762, DEBIAN-CVE-2026-33526, GHSA-hpfx-h48q-gvwg, MINI-p2c6-8976-r3qh, UBUNTU-CVE-2026-33526

## What is CVE-2026-33526?

CVE-2026-33526 is a critical use after free vulnerability in Squid-Cache Squid, published on 26 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-825 (Expired Pointer Dereference), CWE-826 (Premature Release of Resource During Expected Lifetime), CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-33526?

It affects 1 product.


Products: Squid-Cache Squid.

## How do I fix CVE-2026-33526?

Upgrade to a fixed version.

## Is CVE-2026-33526 being exploited?

There is no known exploitation of CVE-2026-33526 in the wild and no public exploit code.

## Other vulnerabilities in Squid-Cache Squid

- [CVE-2025-62168](https://insights.sbomify.com/CVE-2025-62168/): Squid vulnerable to information disclosure via authentication credential leakage in error handling (critical 10.0)
- [CVE-2025-54574](https://insights.sbomify.com/CVE-2025-54574/): Squid's URN Handling can lead to Buffer Overflow (critical 9.3)
- [CVE-2026-32748](https://insights.sbomify.com/CVE-2026-32748/): Squid has Denial of Service in ICP Response handling (high 8.7)
- [CVE-2023-50269](https://insights.sbomify.com/CVE-2023-50269/): SQUID-2023:10 Denial of Service in HTTP Request parsing (high 8.6)
- [CVE-2023-49285](https://insights.sbomify.com/CVE-2023-49285/): Denial of Service in HTTP Message Processing in Squid (high 8.6)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-33526 and fix it if it is affected.

What it is: CVE-2026-33526 is a critical use after free vulnerability in Squid-Cache Squid, published on 26 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-33526 in the wild and no public exploit code.

Affected product: Squid-Cache Squid. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-33526/ (Markdown: https://insights.sbomify.com/CVE-2026-33526/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-33526
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-33526
- OSV: https://osv.dev/vulnerability/CVE-2026-33526

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-33526/
Summaries are generated and may contain mistakes; the official description above is the record.