# CVE-2026-110354: HAProxy 3 before 3.4.6 allows a remote unauthenticated attacker to cause a denial of service (persistent worker-thread CPU exhaustion) via a


- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 22 Oct 2026
- **Updated:** 22 Oct 2026
- **Also known as:** AZL-111017, DEBIAN-CVE-2026-110354, GHSA-vqpp-w68q-p3f5, UBUNTU-CVE-2026-110354

## What is CVE-2026-110354?

CVE-2026-110354 is a high-severity vulnerability in HAProxy, published on 22 Oct 2026. 

### Official description

HAProxy 3 before 3.4.6 allows a remote unauthenticated attacker to cause a denial of service (persistent worker-thread CPU exhaustion) via an HTTP/1.1 chunked request. Although the H1 multiplexer drains the request before closing the stream, the parser repeatedly re-processes the same bytes without making progress. The affected thread stays busy at 100% CPU after timeouts expire and after the client disconnects, and repeated requests can consume all worker threads until the process is restarted.

Weakness: CWE-835 (Loop with Unreachable Exit Condition)

## Which versions are affected by CVE-2026-110354?


## How do I fix CVE-2026-110354?

Upgrade to a fixed version.

## Is CVE-2026-110354 being exploited?

There is no known exploitation of CVE-2026-110354 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-110354 and fix it if it is affected.

What it is: CVE-2026-110354 is a high-severity vulnerability in HAProxy, published on 22 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-110354 in the wild and no public exploit code.

Affected product: HAProxy. 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-2026-110354/ (Markdown: https://insights.sbomify.com/CVE-2026-110354/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-110354
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-110354
- OSV: https://osv.dev/vulnerability/CVE-2026-110354

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-110354/
Summaries are generated and may contain mistakes; the official description above is the record.