Buffer overflow in Openresty
CVE-2026-55233
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 class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.005 (40.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 40th percentile — 40.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000
Affected products
- Openresty — versions >= 1.29.2.1, < 1.29.2.5
Weakness classification (CWE)
References
- github.com/openresty/openresty/security/advisories/GHSA-wx83-v28q-68gx (Mitigation, Vendor Advisory)
- github.com/openresty/openresty/commit/5c56ad2958a2dad8b2cc99f4987b8642cbc647d1 (Patch)
Frequently asked questions
- What is CVE-2026-55233?
- CVE-2026-55233 is a high-severity vulnerability in Openresty, classified under Out-of-bounds Write. CVSS score: 7.5/10. Published 2026-07-10.
- How severe is CVE-2026-55233?
- High severity. CVSS v3 base score is 7.5 out of 10.