CVE-2026-55149

Vouch Proxy: Unbounded Multipart Cookie Allocation DoS

Published Sep 15, 2026 CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed
Description
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-qqff-5854-px68 vouch-proxy has an Unbounded Multipart Cookie Allocation DoS
History
Type Values Removed Values Added
First Time appeared Vouch
Vouch vouch-proxy
Vendors & Products Vouch
Vouch vouch-proxy
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description 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.
Title Vouch Proxy: Unbounded Multipart Cookie Allocation DoS
Weaknesses CWE-789
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Sep 17, 2026, 4:08 PM
Reserved
Jun 16, 2026, 3:13 PM
Status
Deferred
Published
Sep 15, 2026, 5:17 PM
Modified
Sep 30, 2026, 5:51 PM