7.5

CVE-2026-55233: openresty Out-of-bounds Write

CVSS: 7.5v3.1HighAnalyzed
Published 10-07-2026Last modified 13-07-2026
Open JSON

Vulnerability summary

CVE-2026-55233 is a high (CVSS 7.5) Out-of-bounds Write vulnerability in openresty. EPSS estimates a 0.49% chance of exploitation in the next 30 days, higher than 40.6% of scored vulnerabilities.

Overall risk
30/100
0100
Medium · default modelHow is this calculated?
CVSS score
7.5/10
010
High · v3.1 (CVE.org)
EPSS score
0.49%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 10-07-2026
    PublishedVulnerability first disclosed.
  2. 13-07-2026
    Last modifiedVulnerability information updated.

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.

CVSS metrics

2 scores · 2 sources · 1 version

EPSS trend

Probability

0.49%

Chance of exploitation in the next 30 days

Percentile

41%

Versus all other CVEs

30-day change

0.00 pp

From 0.49% on 19-09-2026

19-09-202619-10-2026
EPSS score
0.49%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Openresty1 product

1 vendor · 1 product

References

2 links