CVE-2026-22703
📋 TL;DR
Cosign versions prior to 2.6.2 and 3.0.4 have a vulnerability where crafted bundles can bypass verification checks, allowing malicious actors with compromised identities or signing keys to create valid bundles with arbitrary Rekor entries. This prevents proper auditing of signing events and affects users relying on Cosign for container and binary code signing.
💻 Affected Systems
- Cosign
📦 What is this software?
Cosign by Sigstore
Cosign by Sigstore
⚠️ Risk & Real-World Impact
Worst Case
Attackers with compromised signing keys could create fraudulent signed artifacts that appear legitimate, enabling supply chain attacks with malicious containers or binaries.
Likely Case
Malicious actors could hide unauthorized signing activities, preventing detection and audit of compromised signing events.
If Mitigated
With proper key management and monitoring, impact is limited to audit trail disruption rather than unauthorized artifact execution.
🎯 Exploit Status
Exploitation requires compromised signing credentials or identity, making it targeted rather than opportunistic.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2.6.2 and 3.0.4
Vendor Advisory: https://github.com/sigstore/cosign/security/advisories/GHSA-whqx-f9j3-ch6m
Restart Required: No
Instructions:
1. Update Cosign to version 2.6.2 or 3.0.4. 2. For containerized deployments, rebuild images with updated Cosign binary. 3. Verify bundle verification now properly checks Rekor entry contents.
🔧 Temporary Workarounds
Disable bundle verification
allTemporarily disable Cosign bundle verification until patched
cosign verify --skip-verify-bundle
🧯 If You Can't Patch
- Implement strict access controls for signing keys and credentials
- Monitor Rekor logs for suspicious signing events and verify manually
🔍 How to Verify
Check if Vulnerable:
Run 'cosign version' and check if version is below 2.6.2 or 3.0.4Check Version:
cosign versionVerify Fix Applied:
After updating, verify a known good bundle with 'cosign verify' and ensure it properly validates Rekor entry contents📡 Detection & Monitoring
Log Indicators:
- Failed bundle verification attempts
- Mismatched digests in verification logs
- Unexpected Rekor entry IDs in verification
Network Indicators:
- Unusual patterns of bundle verification requests
- Requests to Rekor with mismatched artifact data
SIEM Query:
source="cosign" AND (event="verify" AND result="success" AND bundle_verification="true") | stats count by artifact_digest