CVE-2026-55149
HIGHDescription
Vouch Proxy is an SSO and OAuth/OIDC login solution for Nginx using the auth_request module. Prior to 0.48.0, Cookie in pkg/cookie/cookie.go parses the total part count from an attacker-controlled multipart cookie name and passes the value to make([]string, numParts) without checking that the value is positive or reasonably bounded. Requests to /validate and /_external-auth-:id reach JWTCacheHandler in pkg/jwtmanager/jwtcache.go, FindJWT in pkg/jwtmanager/jwtmanager.go, and the vulnerable cookie reassembly before JWT validation, so no account or valid session is required. A cookie name such as VouchCookie_1of10000000000 causes an attempted slice allocation of roughly 160 GB and a fatal Go runtime out-of-memory condition, allowing one request to crash the authentication proxy and repeated requests to sustain unavailability. This vulnerability is fixed in 0.48.0.
How to fix
No published remediation has been found for this vulnerability's affected products yet.
Mitigation guidance may be in the linked vendor advisories in the References section below.
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CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Exploit Intelligence
Low risk: more likely to be exploited than 34% of all known CVEs.
References
Related Vulnerabilities
Other CWE-789 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2022-30522 | High | 7.5 | 90% | - | Fix |
| CVE-2026-49975 | High | 7.5 | 34% | - | Fix |
| CVE-2025-27533 | High | 7.5 | 8.7% | - | Fix |
| CVE-2017-7651 | High | 7.5 | 5.2% | - | Fix |
| CVE-2021-31811 | Medium | 5.5 | 3.4% | - | - |
| CVE-2021-27906 | Medium | 5.5 | 3.3% | - | Fix |
Common questions
How do I fix CVE-2026-55149?
No published fix for CVE-2026-55149 has been found yet. Check the linked vendor advisories for guidance as it becomes available.
Is CVE-2026-55149 being actively exploited?
Not that we know of. CVE-2026-55149 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.40% is the estimated probability that it will be exploited in the next 30 days. That is higher than 34% of all scored CVEs.
How severe is CVE-2026-55149?
CVE-2026-55149 has a CVSS v3 base score of 7.5, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-09-17.