Quick answers
- Is CVE-2026-110353 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-110353 being exploited in the wild.
- How severe is CVE-2026-110353?
- High severity, with a CVSS score of 7.5, published 22 October 2026.
- Which products and versions are affected?
- HAProxy 3.2 before 3.4.6.
- Is there a fix for CVE-2026-110353?
- Yes: fixed in 3.4.6. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-110353 attacked?
- It is attacked over the network, in a network appliance.
- Am I affected by CVE-2026-110353?
- Check whether you run HAProxy at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
How to fix
- Fixed in: 3.4.6
Technical details
The vulnerability exists in the h2c_handle_ping function in src/mux_h2.c, which fails to validate short reads on incoming HTTP/2 PING frames. When an incomplete frame is received, the data remains unconsumed, causing the H2 multiplexer tasklet to be repeatedly awakened without progress, resulting in busy-waiting CPU consumption. The attack requires only network access and no authentication, and continues until the http-request timeout closes the connection.
Affected products
- HAProxy HAProxy 3.2 before 3.4.6
Timeline
- 2026-10-22: disclosed