CVE-2026-55233CWE-787

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

High · published July 10, 2026

CVSS v3.1
7.5
EPSS
0%
Percentile
41.1
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
7.5 · HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS v4.0
Not supplied
EPSS
0.00488 · 41.1th percentile
Weakness
CWE-787 · Out-of-bounds Write
Published
2026-07-10T19:59Z
EPSS history
Timeline
  • 10 JUL 19:59Z
    OpenResty: Buffer overflow when writing PROXY protocol v2 header to upstream
    cvelistv5