CVE-2026-55233

HIGH CVSS 3.1: 7.5 EPSS 0.49%
Updated Jul 14, 2026
Openresty
Parameter Value
CVSS 7.5 (HIGH)
Affected Versions 1.29.2.1 — 1.29.2.5
Fixed In 1.29.2.5
Type CWE-787 (Out-of-bounds Write)
Vendor Openresty
Public PoC No

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.

Attack Parameters

Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed

Impact Assessment

Confidentiality
None
No data leak
Integrity
None
No data modification
Availability
High
Complete denial of service

CVSS Vector v3.1

Weakness Type (CWE)

Vulnerable Products 1

Configuration From (including) Up to (excluding)
Openresty Openresty
cpe:2.3:a:openresty:openresty:*:*:*:*:*:*:*:*
1.29.2.1 1.29.2.5