vouch-proxy has an Unbounded Multipart Cookie Allocation DoS

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

• CVE-2026-55149: 0.72% estimated exploitation activity in the next 30 days; percentile 53.89 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Unbounded Multipart Cookie Allocation DoS in vouch-proxy Summary vouch-proxy v0.47.2 contains an unauthenticated remote denial-of-service vulnerability in its multipart cookie reassembly logic. The /validate endpoint parses the total cookie part count directly from the attacker-controlled cookie name (e.g., VouchCookie1of<N) and passes it without any bounds check to make([]string, N). A single HTTP request with N=10000000000 causes the Go runtime to attempt a ~160 GB heap allocation, triggering a fatal out-of-memory error that crashes the server process immediately. No authentication or prior session is required. Details The vulnerability exists in pkg/cookie/cookie.go. The Cookie() function iterates over all cookies in the request, identifies multipart cookies by the NofM suffix in their name, and initializes the reassembly slice on the first matching cookie: The value in xyArray[1] comes directly from the cookie name supplied by the client. There is no maximum value check, no…

Published by the source

20 Aug 2026, 17:26 UTC

Last modified by the source

1 Oct 2026, 08:56 UTC

Source last checked

26 Oct 2026, 15:29 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-qqff-5854-px68

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GO-2026-6260

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-qqff-5854-px68

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# Patch Next advisory brief: CVE-2026-55149

Advisory: vouch-proxy has an Unbounded Multipart Cookie Allocation DoS
IDs: CVE-2026-55149, GHSA-qqff-5854-px68
Record: https://patchnext.com/advisories/cve-2026-55149 (revision 3, source checked 26 Oct 2026, 15:29 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/vouch/vouch-proxy 0.48.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/vouch/vouch-proxy: affected <= 0.47.2; fixed in 0.48.0

## Suggested inspection (read-only)
- Go github.com/vouch/vouch-proxy: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/vouch/vouch-proxy.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-qqff-5854-px68 (OSV record GHSA-qqff-5854-px68 lists affected ranges: Go github.com/vouch/vouch-proxy >=0 <0.48.0 (fixed))
- Verified: https://osv.dev/vulnerability/GO-2026-6260 (OSV record GO-2026-6260 lists affected ranges: Go github.com/vouch/vouch-proxy >=0 <0.48.0 (fixed))
- Verified: https://github.com/advisories/GHSA-qqff-5854-px68 (GitHub-reviewed advisory GHSA-qqff-5854-px68 lists affected ranges: Go github.com/vouch/vouch-proxy >=0 <=0.47.2)

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