UpHeron
All vulnerabilities

Servers and applications

CVE-2026-55203

HAProxy through 3.4.0, fixed in commit 5985276, contains an integer overflow vulnerability in the fcgi_conn structure's drl field that allows buffer misparse as new FCGI record headers. When contentLength is 65535 and paddingLength is 1 or more, the drl field wraps to 0, causing incorrect record consumption and allowing malicious FastCGI backends to desynchronize the FCGI framing parser,…

Severity
Critical 9.0
Published
18 Jun 2026
Last changed
8 Oct 2026
Added to UpHeron
21 Oct 2026
Fixed in
2.4.36, 2.6.30, 2.8.25, 3.0.24, 3.2.20, 3.4.1
Sources
NVD

Affected software

SoftwareAffected versions
HAProxyServers and applications · cpe:a:haproxy:haproxy
  • Every version before 2.4.36
  • From 2.5 before 2.6.30
  • From 2.7 before 2.8.25
  • From 2.9 before 3.0.24
  • From 3.1 before 3.2.20
  • From 3.3 before 3.4.1

References

  • NVD https://nvd.nist.gov/vuln/detail/CVE-2026-55203
  • CVE.org https://www.cve.org/CVERecord?id=CVE-2026-55203