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Openresty CVE-2026-55233

| EUVDEUVD-2026-43013 HIGH
Out-of-bounds Write (CWE-787)
2026-07-10 GitHub_M
7.5
CVSS 3.1 · Vendor: GitHub_M
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Severity by source

Vendor (GitHub_M) PRIMARY
7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Primary rating from Vendor (GitHub_M) · only source for this CVE.

CVSS VectorVendor: GitHub_M

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

2
Patch available
Jul 10, 2026 - 22:02 EUVD
Analysis Generated
Jul 10, 2026 - 21:16 vuln.today

DescriptionCVE.org

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.

AnalysisAI

Denial of service in OpenResty 1.29.2.1 through 1.29.2.4 arises from an out-of-bounds write (CWE-787) in the upstream PROXY protocol v2 implementation; when the platform is configured to prepend PROXY protocol v2 headers to upstream connections, header construction in the stream proxy-protocol-v2 patch overruns its allocated buffer and crashes the worker process. Any environment that has explicitly enabled PROXY protocol v2 for upstream connections is affected, degrading availability without any impact to confidentiality or integrity. …

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Recommended ActionAI

Within 24 hours: Inventory OpenResty deployments and identify which have PROXY protocol v2 enabled for upstream connections. …

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CVE-2026-55233 vulnerability details – vuln.today

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