CVE Catalog

CVE-2026-55233

HighCVSS 7.5
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.34%

27th percentile - higher than 27% of all known CVEs

Summary

In OpenResty from version 1.29.2.1 to before 1.29.2.5, an out-of-bounds write vulnerability exists in the upstream PROXY protocol v2 implementation. An attacker can cause the worker process to crash, leading to a denial of service (DoS). Only configurations with explicitly enabled PROXY protocol v2 for upstream connections are affected.

Risk Assessment

The risk is the potential disruption of service by intentionally crashing the OpenResty worker process. This can lead to unavailability of web applications for users.

Recommendation

Immediately upgrade OpenResty to version 1.29.2.5 or later. If upgrading is not possible, temporarily disable PROXY protocol v2 for upstream connections.

Related vulnerabilities

Original NVD description (English source)

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.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS