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OpenAdvisories
High · 7.5 CVE-2026-55233 EUVD-2026-43013

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

Published Jul 10, 2026 · Updated Jul 13, 2026 · Assigned by GitHub_M

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

VendorProductAffectedFixed
openresty openresty >= 1.29.2.1, < 1.29.2.5 —

References