CVE-2026-55233 PUBLISHED

OpenResty: Buffer overflow when writing PROXY protocol v2 header to upstream

Assigner: GitHub_M
Reserved: 16.06.2026 Published: 10.07.2026 Updated: 10.07.2026

OpenResty is a high performance web platform. From 1.29.2.1 to before 1.29.2.5, an out-of-bounds write vulnerability exists in the upstream PROXY protocol v2 implementation. When OpenResty is configured to send PROXY protocol version 2 headers to upstream servers, constructing the header in the stream proxy protocol v2 patch can write beyond the bounds of the allocated buffer, causing the worker process to crash and resulting in a denial of service. Only configurations that explicitly enable PROXY protocol v2 for upstream connections are impacted. This issue is fixed in version 1.29.2.5.

Metrics

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS Score: 7.5

Product Status

Vendor openresty
Product openresty
Versions
  • Version >= 1.29.2.1, < 1.29.2.5 is affected

References

Problem Types

  • CWE-787: Out-of-bounds Write CWE