How severe is CVE-2026-22703?

CVE-2026-22703 has a CVSS score of 5.5/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2026-22703?

CVE-2026-22703 affects the following packages: github.com/sigstore/cosign/v3 (Go), github.com/sigstore/cosign/v2 (Go). Ecosystems affected: Go.

How do I fix CVE-2026-22703?

Update github.com/sigstore/cosign/v3 to 3.0.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-22703 is resolved across your whole dependency graph.

How do I detect CVE-2026-22703 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/sigstore/cosign/v3, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-22703 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2026-22703 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-22703 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-22703?

CVE-2026-22703 has an EPSS (Exploit Prediction Scoring System) score of 0.1%, placing it in the 1th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-22703?

CVE-2026-22703 is classified as CWE-345 (CWE-345). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-22703 published, and has it been updated?

CVE-2026-22703 was published on January 10, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹

🐹 Go

Not in CISA KEV

MEDIUM severity

CVE-2026-22703 — cosign

MEDIUMFix: sigstore/cosign@6832fba

CVE-2026-22703 is a medium-severity (CVSS 5.5) CWE-345 vulnerability in github.com/sigstore/cosign/v3. A fix is available for github.com/sigstore/cosign/v3 — see the affected versions and patch details below.

Cosign verification accepts any valid Rekor entry under certain conditions

Also known asBIT-cosign-2026-22703GHSA-whqx-f9j3-ch6mGO-2026-4309

Published

Jan 10, 2026

Updated

Oct 28, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Oct 31, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-22703.

EPSS Exploitation Probability

via FIRST.org ↗

0.1%probability of exploitation in next 30 days

Lower Risk-0.00%

Lower risk than most CVEs1th percentile — riskier than 1% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

2 pkgs affected

🐹github.com/sigstore/cosign/v3🐹github.com/sigstore/cosign/v2

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

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 SIGSTORE_REKOR_PUBLIC_KEY. When using the default flag values in Cosign v3 to sign and verify (--use-signing-config=true and --new-bundle-format=true for signing, --new-bundle-format=true for verification), users are unaffected. Cosign v2 users are affected using the default flag values.

This issue had previously been fixed in https://github.com/sigstore/cosign/security/advisories/GHSA-8gw7-4j42-w388 but recent refactoring caused a regression. We have added testing to prevent a future regression.

Steps to Reproduce

echo blob > /tmp/blob
cosign sign-blob -y --new-bundle-format=false --bundle /tmp/bundle.1 --use-signing-config=false /tmp/blob
cosign sign-blob -y --new-bundle-format=false --bundle /tmp/bundle.2 --use-signing-config=false /tmp/blob
jq ".rekorBundle |= $(jq .rekorBundle /tmp/bundle.2)" /tmp/bundle.1 > /tmp/bundle.3
cosign verify-blob --bundle /tmp/bundle.3 --certificate-identity-regexp='.*' --certificate-oidc-issuer-regexp='.*' /tmp/blob

Patches

Upgrade to Cosign v2.6.2 or Cosign v3.0.4. This does not affect Cosign v1.

Workarounds

You can provide trusted key material via a set of flags under certain conditions. The simplest fix is to upgrade to the latest Cosign v2 or v3 release.

Note that the example below works for cosign verify, cosign verify-blob, cosign verify-blob-attestation, and cosign verify-attestation`.

SIGSTORE_REKOR_PUBLIC_KEY=<path to Rekor pub key> cosign verify-blob --use-signing-config=false --new-bundle-format=false --bundle=<path to bundle> <artifact>

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/sigstore/cosign/v3`	all versions	3.0.4`go get github.com/sigstore/cosign/v3@v3.0.4`
🐹Go	`github.com/sigstore/cosign/v2`	all versions	2.6.2`go get github.com/sigstore/cosign/v2@v2.6.2`

Affected Products

1 product · 2 configurations

Application

cosignsigstore

≥ 3.0.0 && < 3.0.4

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/sigstore/cosign/v3, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/sigstore/cosign/v3 to 3.0.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-22703 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

Workaround published by Red Hat

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.

Source: Red Hat security advisory for CVE-2026-22703 (CC BY 4.0)

Frequently Asked Questions

### 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 v