Cosign verification accepts any valid Rekor entry under certain conditions

Exploitation

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

CVSS

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

EPSS

• CVE-2026-22703: 0.11% estimated exploitation activity in the next 30 days; percentile 1.11 (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 A Cosign bundle can be crafted to successfully verify an artifact even if the embedded Rekor entry does not reference the artifact's digest, signature or public key. When verifying a Rekor entry, Cosign verifies the Rekor entry signature, and also compares the artifact's digest, the user's public key from either a Fulcio certificate or provided by the user, and the artifact signature to the Rekor entry contents. Without these comparisons, Cosign would accept any response from Rekor as valid. A malicious actor that has compromised a user's identity or signing key could construct a valid Cosign bundle by including any arbitrary Rekor entry, thus preventing the user from being able to audit the signing event. This vulnerability only affects users that provide a trusted root via --trusted-root or when fetched automatically from a TUF repository, when no trusted key material is provided via SIGSTOREREKORPUBLICKEY. When using the default flag values in Cosign v3 to sign and verify…

Published by the source

13 Jan 2026, 14:58 UTC

Last modified by the source

13 Jan 2026, 14:58 UTC

Source last checked

26 Oct 2026, 15:14 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-whqx-f9j3-ch6m

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# Patch Next advisory brief: CVE-2026-22703

Advisory: Cosign verification accepts any valid Rekor entry under certain conditions
IDs: CVE-2026-22703, GHSA-whqx-f9j3-ch6m
Record: https://patchnext.com/advisories/cve-2026-22703 (revision 1, source checked 26 Oct 2026, 15:14 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/sigstore/cosign/v3 3.0.4; github.com/sigstore/cosign/v2 2.6.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/sigstore/cosign/v3: affected <= 3.0.3; fixed in 3.0.4
- Go github.com/sigstore/cosign/v2: affected <= 2.6.1; fixed in 2.6.2

## Suggested inspection (read-only)
- Go github.com/sigstore/cosign/v3: check the installed version with your package manager.
- Go github.com/sigstore/cosign/v2: 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/sigstore/cosign/v3, github.com/sigstore/cosign/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-whqx-f9j3-ch6m (GitHub-reviewed advisory GHSA-whqx-f9j3-ch6m lists affected ranges: Go github.com/sigstore/cosign/v3 >=0 =0 <=2.6.1)

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