CVE-2026-110354
HAProxy 3 before 3.4.6 allows a remote unauthenticated attacker to cause a denial of service ...
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
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.
- Record
CVE-2026-110354- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-835
- Updated
- 2026-11-02
EUVDEUVD-2026-108000
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.
- Record
EUVD-2026-108000- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-vqpp-w68q-p3f5
HAProxy 3 before 3.4.6 allows a remote unauthenticated attacker to cause a denial of service ...
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.
- Record
GHSA-vqpp-w68q-p3f5- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-835
- Updated
- 2026-11-02
NVD
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.
- Record
CVE-2026-110354- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-835
- Updated
- 2026-11-02
OSV
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.
- Record
CVE-2026-110354- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-835
- Updated
- 2026-11-06
OSVDEBIAN-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 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.
- Record
DEBIAN-CVE-2026-110354- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
Show 4 moreShow less
OSVUBUNTU-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 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.
- Record
UBUNTU-CVE-2026-110354- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-03
OSVAZL-111017 No score
CVE-2026-110354 affecting package haproxy for versions less than 2.9.11-9
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.
- Record
AZL-111017- Updated
- 2026-11-05
OSVopenSUSE-SU-2026:12431-1 No score
haproxy-3.4.7+git57.0faeaeda6-2.1 on GA media
These are all security issues fixed in the haproxy-3.4.7+git57.0faeaeda6-2.1 package on the GA media of openSUSE Tumbleweed.
- Record
openSUSE-SU-2026:12431-1- Updated
- 2026-11-06
OSVUSN-8972-1 No score
haproxy vulnerabilities
It was discovered that HAProxy incorrectly handled truncated HTTP/2 PING frames. A remote attacker could possibly use this issue to cause HAProxy to consume excessive CPU resources, leading to a denial of service. (CVE-2026-110353)
It was discovered that HAProxy incorrectly handled certain HTTP/1.1 chunked requests. A remote attacker could possibly use this issue to cause HAProxy to consume excessive CPU resources, leading to a denial of service. (CVE-2026-110354)
- Record
USN-8972-1- Updated
- 2026-11-04
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
haproxyAzure Linux:3 |
before 2.9.11-9 | 2.9.11-9 |
haproxyDebian:12 |
before 2.6.12-1+deb12u4, plus listed versions 2.6.12-12.6.12-1+deb12u12.6.12-1+deb12u22.6.12-1+deb12u3 |
2.6.12-1+deb12u4 |
haproxyDebian:13 |
before 3.0.11-1+deb13u4, plus listed versions 3.0.11-13.0.11-1+deb13u13.0.11-1+deb13u23.0.11-1+deb13u3 |
3.0.11-1+deb13u4 |
haproxyDebian:14 |
before 3.2.26-1, plus listed versions 3.0.11-13.1.0-13.1.0-23.1.1-13.1.2-1 Show 32 moreShow less3.1.3-13.1.5-13.1.6-13.1.7-13.2.0-13.2.1-13.2.10-13.2.11-13.2.11-23.2.12-13.2.13-13.2.14-13.2.15-13.2.16-13.2.17-13.2.18-13.2.19-13.2.20-13.2.21-13.2.22-13.2.23-13.2.24-13.2.25-13.2.3-13.2.3-23.2.4-13.2.5-13.2.5-23.2.6-13.2.7-13.2.8-13.2.9-1 |
3.2.26-1 |
haproxyUbuntu:Pro:16.04:LTS |
All versions, plus listed versions 1.5.14-11.5.15-11.6.2-11.6.2-21.6.2-2ubuntu1 Show 7 moreShow less1.6.2-2ubuntu31.6.3-11.6.3-1ubuntu0.11.6.3-1ubuntu0.21.6.3-1ubuntu0.31.6.3-1ubuntu0.3+esm11.6.3-1ubuntu0.3+esm2 |
None known |
haproxyUbuntu:Pro:18.04:LTS |
All versions, plus listed versions 1.7.9-1ubuntu11.7.9-1ubuntu21.8.4-11.8.7-11.8.8-1 Show 13 moreShow less1.8.8-1ubuntu0.11.8.8-1ubuntu0.21.8.8-1ubuntu0.31.8.8-1ubuntu0.41.8.8-1ubuntu0.61.8.8-1ubuntu0.71.8.8-1ubuntu0.81.8.8-1ubuntu0.91.8.8-1ubuntu0.101.8.8-1ubuntu0.111.8.8-1ubuntu0.131.8.8-1ubuntu0.13+esm21.8.8-1ubuntu0.13+esm3 |
None known |
haproxyUbuntu:20.04:LTS |
All versions, plus listed versions 2.0.5-12.0.8-12.0.9-12.0.10-12.0.10-1ubuntu1 Show 15 moreShow less2.0.11-1ubuntu12.0.12-1ubuntu22.0.13-1ubuntu22.0.13-22.0.13-2ubuntu0.12.0.13-2ubuntu0.22.0.13-2ubuntu0.32.0.13-2ubuntu0.52.0.29-0ubuntu12.0.29-0ubuntu1.12.0.29-0ubuntu1.32.0.31-0ubuntu0.12.0.31-0ubuntu0.22.0.31-0ubuntu0.32.0.33-0ubuntu0.1 |
None known |
haproxyUbuntu:22.04:LTS |
before 2.4.30-0ubuntu0.22.04.3, plus listed versions 2.2.9-2ubuntu22.4.8-12.4.8-2ubuntu32.4.11-1ubuntu12.4.12-1ubuntu1 Show 16 moreShow less2.4.12-1ubuntu22.4.13-1ubuntu12.4.14-1ubuntu12.4.18-0ubuntu12.4.18-0ubuntu1.12.4.18-0ubuntu1.22.4.18-0ubuntu1.32.4.22-0ubuntu0.22.04.12.4.22-0ubuntu0.22.04.22.4.22-0ubuntu0.22.04.32.4.24-0ubuntu0.22.04.12.4.24-0ubuntu0.22.04.22.4.24-0ubuntu0.22.04.32.4.29-0ubuntu0.22.04.12.4.30-0ubuntu0.22.04.12.4.30-0ubuntu0.22.04.2 |
2.4.30-0ubuntu0.22.04.3 |
haproxyUbuntu:24.04:LTS |
before 2.8.30-0ubuntu0.24.04.2, plus listed versions 2.6.15-1ubuntu22.8.5-1ubuntu12.8.5-1ubuntu22.8.5-1ubuntu32.8.5-1ubuntu3.1 Show 8 moreShow less2.8.5-1ubuntu3.22.8.5-1ubuntu3.32.8.5-1ubuntu3.42.8.15-0ubuntu0.24.04.12.8.16-0ubuntu0.24.04.12.8.16-0ubuntu0.24.04.22.8.16-0ubuntu0.24.04.32.8.30-0ubuntu0.24.04.1 |
2.8.30-0ubuntu0.24.04.2 |
haproxyUbuntu:26.10 |
before 3.4.2-1ubuntu4.1, plus listed versions 3.2.9-1ubuntu23.2.9-1ubuntu2.13.2.9-1ubuntu33.4.2-1ubuntu23.4.2-1ubuntu33.4.2-1ubuntu4 |
3.4.2-1ubuntu4.1 |
Show 6 moreShow less
| Package | Affected | Fixed |
|---|---|---|
haproxyUbuntu:26.04:LTS |
before 3.2.25-0ubuntu0.26.04.2, plus listed versions 3.0.10-1ubuntu33.2.9-1ubuntu13.2.9-1ubuntu23.2.9-1ubuntu2.13.2.9-1ubuntu2.23.2.25-0ubuntu0.26.04.1 |
3.2.25-0ubuntu0.26.04.2 |
haproxyUbuntu:22.04:LTS From an advisory covering 2 CVEs |
before 2.4.30-0ubuntu0.22.04.3, plus listed versions 2.2.9-2ubuntu22.4.8-12.4.8-2ubuntu32.4.11-1ubuntu12.4.12-1ubuntu1 Show 16 moreShow less2.4.12-1ubuntu22.4.13-1ubuntu12.4.14-1ubuntu12.4.18-0ubuntu12.4.18-0ubuntu1.12.4.18-0ubuntu1.22.4.18-0ubuntu1.32.4.22-0ubuntu0.22.04.12.4.22-0ubuntu0.22.04.22.4.22-0ubuntu0.22.04.32.4.24-0ubuntu0.22.04.12.4.24-0ubuntu0.22.04.22.4.24-0ubuntu0.22.04.32.4.29-0ubuntu0.22.04.12.4.30-0ubuntu0.22.04.12.4.30-0ubuntu0.22.04.2 |
2.4.30-0ubuntu0.22.04.3 |
haproxyUbuntu:24.04:LTS From an advisory covering 2 CVEs |
before 2.8.30-0ubuntu0.24.04.2, plus listed versions 2.6.15-1ubuntu22.8.5-1ubuntu12.8.5-1ubuntu22.8.5-1ubuntu32.8.5-1ubuntu3.1 Show 8 moreShow less2.8.5-1ubuntu3.22.8.5-1ubuntu3.32.8.5-1ubuntu3.42.8.15-0ubuntu0.24.04.12.8.16-0ubuntu0.24.04.12.8.16-0ubuntu0.24.04.22.8.16-0ubuntu0.24.04.32.8.30-0ubuntu0.24.04.1 |
2.8.30-0ubuntu0.24.04.2 |
haproxyUbuntu:26.10 From an advisory covering 2 CVEs |
before 3.4.2-1ubuntu4.1, plus listed versions 3.2.9-1ubuntu23.2.9-1ubuntu2.13.2.9-1ubuntu33.4.2-1ubuntu23.4.2-1ubuntu33.4.2-1ubuntu4 |
3.4.2-1ubuntu4.1 |
haproxyUbuntu:26.04:LTS From an advisory covering 2 CVEs |
before 3.2.25-0ubuntu0.26.04.2, plus listed versions 3.0.10-1ubuntu33.2.9-1ubuntu13.2.9-1ubuntu23.2.9-1ubuntu2.13.2.9-1ubuntu2.23.2.25-0ubuntu0.26.04.1 |
3.2.25-0ubuntu0.26.04.2 |
haproxyopenSUSE:Tumbleweed From an advisory covering 2 CVEs |
before 3.4.7+git57.0faeaeda6-2.1 | 3.4.7+git57.0faeaeda6-2.1 |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, aliases, references | OSV | |
| affected | OSV | |
| affected, aliases, references | OSV | |
| affected, facts, references | OSV | |
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-110354 is a high vulnerability (CVSS 7.5) in Haproxy, published October 22, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.81%, the 57th percentile. Fixed in haproxy 2.9.11-9.
References
git.haproxy.org?p=haproxy.git;a=commit;h=077906da140a35873bf451d7e9f67646c9f37c81
nvd.nist.gov/vuln/detail/CVE-2026-110354
github.com/advisories/GHSA-vqpp-w68q-p3f5
security-tracker.debian.org/tracker/CVE-2026-110354