CVE-2023-40225
HAProxy through 2.0.32, 2.1.x and 2.2.x through 2.2.30, 2.3.x and 2.4.x through 2.4.23, 2.5.x and 2.6.x before 2.6.15, 2.7.x before 2.7.10, and 2.8.x before 2.8.2 forwards empty Content-Length headers, violating RFC 9110 section 8.6.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (2.15%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
HAProxy through 2.0.32, 2.1.x and 2.2.x through 2.2.30, 2.3.x and 2.4.x through 2.4.23, 2.5.x and 2.6.x before 2.6.15, 2.7.x before 2.7.10, and 2.8.x before 2.8.2 forwards empty Content-Length headers, violating RFC 9110 section 8.6. In uncommon cases, an HTTP/1 server behind HAProxy may interpret the payload as an extra request.
- CVSS 3.1
- 7.2 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
- EPSS
- 2.15% probability · 82th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-444
- Affected
- haproxy/haproxy
- Source
- cve@mitre.org
EPSS 2.1% since 27 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://cwe.mitre.org/data/definitions/436.htmlTechnical Description
- https://github.com/haproxy/haproxy/commit/6492f1f29d738457ea9f382aca54537f35f9d856Patch
- https://github.com/haproxy/haproxy/issues/2237Exploit, Issue Tracking, Vendor Advisory
- https://www.haproxy.org/download/2.6/src/CHANGELOGRelease Notes
- https://www.haproxy.org/download/2.7/src/CHANGELOGRelease Notes
- https://www.haproxy.org/download/2.8/src/CHANGELOGRelease Notes
- https://cwe.mitre.org/data/definitions/436.htmlTechnical Description
- https://github.com/haproxy/haproxy/commit/6492f1f29d738457ea9f382aca54537f35f9d856Patch
- https://github.com/haproxy/haproxy/issues/2237Exploit, Issue Tracking, Vendor Advisory
- https://www.haproxy.org/download/2.6/src/CHANGELOGRelease Notes
- https://www.haproxy.org/download/2.7/src/CHANGELOGRelease Notes
- https://www.haproxy.org/download/2.8/src/CHANGELOGRelease Notes
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.