CVE-2026-55233 in OpenResty
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,...
Quick answer
OpenResty should be reviewed and updated if it matches the affected versions. The recommended fix is to apply the vendor-supported patched version or the mitigation steps below, then retest the public website with Fixnx.
Who is affected
Affected versions
- OpenResty >=1.29.2.1 <1.29.2.5
Fixed versions
- OpenResty 1.29.2.5 or later
How to fix it
Update OpenResty. The old build can crash workers when PROXY protocol v2 is used upstream.
- Upgrade OpenResty to OpenResty 1.29.2.5 or later.
- Restart OpenResty safely.
- Review stream proxy protocol settings.
- Watch worker crash logs after release.
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Verify the fix
- Run openresty -v and confirm the fixed version.
- Scan again and confirm CVE-2026-55233 is gone.
Related categories
Trusted references
FAQ
What is affected by CVE-2026-55233?
OpenResty versions listed as affected should be reviewed: OpenResty >=1.29.2.1 <1.29.2.5.
What should I fix first?
Start with internet-facing sites, admin panels, login flows, plugins, themes, modules, packages, and systems that process user-controlled input or sensitive data.
How do I confirm the fix worked?
Apply the patched version or mitigation, clear caches where relevant, retest the affected workflow, and run a new Fixnx scan to verify public website exposure signals.
How are Fixnx security risk categories chosen?
Fixnx keeps one canonical risk page and assigns only broad, relevant categories such as ecosystem, technology area, or vulnerability class.