# CVE-2026-110353: haproxy: HAProxy 3.2 before 3.4.6 allows a remote unauthenticated attacker to cause a denial of service (worker-thread CPU exh...

CVE-2026-110353 is fixed in 2 products on 1 platform, first by DEBIAN-CVE-2026-110353, released October 25, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-110353
- Priority: High
- CVSS: 7.5 (high)
- EPSS: 0.0074
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Oct 21, 2026

## Description

HAProxy 3.2 before 3.4.6 allows a remote unauthenticated attacker to cause a denial of service (worker-thread CPU exhaustion) via a truncated HTTP/2 PING frame. h2c_handle_ping in src/mux_h2.c does not check for a short read, unlike the other H2 frame handlers. Because the incomplete frame cannot be processed, its data is never consumed, and the H2 multiplexer tasklet is repeatedly woken by that pending data without making progress. The CPU spins until timeout http-request closes the connection, and an attacker opening many such connections can sustain high CPU usage.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | haproxy Debian 14 | 3.2.26-1 | [DEBIAN-CVE-2026-110353](https://patchblox.com/security/data/fix/linux/debian-cve-2026-110353.md) | Oct 25, 2026 |
| Linux | haproxy Ubuntu 22.04.1 LTS (jammy) | 2.4.30-0ubuntu0.22.04.3 | [haproxy 2.4.30-0ubuntu0.22.04.3](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-haproxy-2.4.30-0ubuntu0.22.04.3.md) | Nov 4, 2026 |
| Linux | haproxy Ubuntu 24.04.5 LTS (noble) | 2.8.30-0ubuntu0.24.04.2 | [haproxy 2.8.30-0ubuntu0.24.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-noble-haproxy-2.8.30-0ubuntu0.24.04.2.md) | Nov 4, 2026 |
| Linux | haproxy Ubuntu 26.04.1 LTS (resolute) | 3.2.25-0ubuntu0.26.04.2 | [haproxy 3.2.25-0ubuntu0.26.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-haproxy-3.2.25-0ubuntu0.26.04.2.md) | Nov 7, 2026 |
| Linux | vim-haproxy Ubuntu 22.04.1 LTS (jammy) | 2.4.30-0ubuntu0.22.04.3 | [vim-haproxy 2.4.30-0ubuntu0.22.04.3](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-vim-haproxy-2.4.30-0ubuntu0.22.04.3.md) | Nov 4, 2026 |
| Linux | vim-haproxy Ubuntu 24.04.5 LTS (noble) | 2.8.30-0ubuntu0.24.04.2 | [vim-haproxy 2.8.30-0ubuntu0.24.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-noble-vim-haproxy-2.8.30-0ubuntu0.24.04.2.md) | Nov 4, 2026 |
| Linux | vim-haproxy Ubuntu 26.04.1 LTS (resolute) | 3.2.25-0ubuntu0.26.04.2 | [vim-haproxy 3.2.25-0ubuntu0.26.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-vim-haproxy-3.2.25-0ubuntu0.26.04.2.md) | Nov 7, 2026 |

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Data as of 2026-11-08T19:12:23Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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