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

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Summary

CVECVE-2026-55233
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-10 21:16:55 UTC
Updated2026-07-14 19:20:51 UTC
DescriptionOpenResty 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.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS: 0.003430000 probability, percentile 0.265020000 (date 2026-07-15)

Problem Types: CWE-787 | CWE-787 CWE-787: Out-of-bounds Write

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1CNADECLARED7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Openresty Openresty All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Openresty Openresty affected >= 1.29.2.1, < 1.29.2.5 Not specified

References

ReferenceSourceLinkTags
github.com/openresty/openresty/commit/5c56ad2958a2dad8b2cc99f4987b8642cb... [email protected] github.com Patch
github.com/openresty/openresty/security/advisories/GHSA-wx83-v28q-68gx [email protected] github.com Mitigation, Vendor Advisory
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