Vulnerability · Published Jul 10, 2026 · Assigned by GitHub_M

CVE-2026-55233OpenResty: Buffer overflow when writing PROXY protocol v2 header to upstream

High 7.5

In plain English

A high-severity out-of-bounds write in openresty from openresty. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 42% of all known vulnerabilities).

Severity (CVSS 3.1)7.5High

Exploit odds (30 days)0.5%top 57.8% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

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.

Affected products (as reported)

Vendor	Product	Versions
openresty	openresty	>= 1.29.2.1, < 1.29.2.5

Weakness: CWE-787 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

https://github.com/openresty/openresty/security/advisories/GHSA-wx83-v28q-68gx x_refsource_CONFIRM
https://github.com/openresty/openresty/commit/5c56ad2958a2dad8b2cc99f4987b8642cbc647d1 x_refsource_MISC