Sigstore Timestamp Authority has OOM due to unbounded metric label cardinality

Exploitation

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

CVSS

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

EPSS

• CVE-2026-49835: 0.74% estimated exploitation activity in the next 30 days; percentile 54.80 (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.

Impact An unauthenticated remote attacker can trigger unbounded memory growth on the timestamp authority server. This vulnerability exists because the global wrapMetrics middleware records the raw HTTP request path (r.URL.Path) and raw HTTP request method (r.Method) as Prometheus labels for latency and request count metric vectors. Since this middleware runs before standard routing occurs, it executes for all incoming requests, including those for unmatched paths (yielding 404 responses) or arbitrary request methods. The Prometheus library registers a new, permanent time-series entry for every distinct label combination. An attacker can continuously issue requests containing random paths (e.g., /api/v1/timestamp/<uuid) or random HTTP methods to exhaust system memory. Patches This issue has been patched by limiting the metric label values to a strict allowlist of expected paths (/ping, /api/v1/timestamp, /api/v1/timestamp/certchain) and expected HTTP methods (GET, POST, HEAD,…

Published by the source

30 Jun 2026, 18:40 UTC

Last modified by the source

30 Jun 2026, 18:40 UTC

Source last checked

26 Oct 2026, 15:24 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-9c54-x2g4-v92j

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# Patch Next advisory brief: CVE-2026-49835

Advisory: Sigstore Timestamp Authority has OOM due to unbounded metric label cardinality
IDs: CVE-2026-49835, GHSA-9c54-x2g4-v92j
Record: https://patchnext.com/advisories/cve-2026-49835 (revision 1, source checked 26 Oct 2026, 15:24 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Partial vendor fix; fixed versions by package: github.com/sigstore/timestamp-authority/v2 2.1.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/sigstore/timestamp-authority: affected <= 1.2.9
- Go github.com/sigstore/timestamp-authority/v2: affected <= 2.0.6; fixed in 2.1.0

## Suggested inspection (read-only)
- Go github.com/sigstore/timestamp-authority: check the installed version with your package manager.
- Go github.com/sigstore/timestamp-authority/v2: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/sigstore/timestamp-authority, github.com/sigstore/timestamp-authority/v2.
- 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://github.com/advisories/GHSA-9c54-x2g4-v92j (GitHub-reviewed advisory GHSA-9c54-x2g4-v92j lists affected ranges: Go github.com/sigstore/timestamp-authority/v2 >=0 =0 <=1.2.9)

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