# CVE-2026-122323: Kyverno unbounded decompression in notary signature fetch

Source: https://junglewise.ai/threats/cve-2026-122323-kyverno-from-1-11-0-before-1-19-2-contains-an-unbounded  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-05. Updated: 2026-11-05  
License: CC BY 4.0 with a link back

CVE-2026-122323 · Severity: high · CVSS 7.5 · Published 2026-11-05

Kyverno is a policy engine that validates Kubernetes container images using cryptographic signatures. An attacker who can publish container image signatures can supply a small compressed file that expands to enormous size in memory, exhausting the admission controller's memory and forcing it to crash, disrupting cluster operations and preventing new workloads from being admitted.

Technologies: [Kyverno](https://junglewise.ai/threats/technologies/kyverno). Vendors: [Kyverno](https://junglewise.ai/threats/vendors/kyverno).

## Quick answers

**Is CVE-2026-122323 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-122323 being exploited in the wild.

**How severe is CVE-2026-122323?** High severity, with a CVSS score of 7.5, published 5 November 2026.

**Which products and versions are affected?** Kyverno 1.11.0 through 1.16.2.

**Is there a fix for CVE-2026-122323?** Yes: fixed in 1.19.2. Until then: Enforce an upper bound on uncompressed reads using io.LimitReader with maxPayloadSize+1 and error on exceeded limits. Close uncompressed readers properly with defer. Apply the same uncompressed-size enforcement to related callsites in pkg/cosign/sigstore.go and pkg/notary/notary.go that read Layer.Uncompressed() into memory buffers. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-122323 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-122323?** Check whether you run Kyverno at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in 1.19.2

Enforce an upper bound on uncompressed reads using io.LimitReader with maxPayloadSize+1 and error on exceeded limits. Close uncompressed readers properly with defer. Apply the same uncompressed-size enforcement to related callsites in pkg/cosign/sigstore.go and pkg/notary/notary.go that read Layer.Uncompressed() into memory buffers.

## Technical details

The FetchSignatureBlob function in pkg/notary/repository.go validates the compressed size of notary signature layers but does not enforce a limit on the uncompressed payload size. An attacker with registry write access can craft a gzip-compressed layer that decompresses far beyond the maxPayloadSize (10MB) limit, causing unbounded memory allocation when the stream is read into memory via io.ReadFrom. This requires Kyverno deployed as an admission controller with image verification enabled.

## Affected products

- Kyverno Kyverno 1.11.0 through 1.16.2

## Timeline

- 2026-10-21: disclosed
- 2026-11-05: advisory
- 2026-11-05: patched: version 1.19.2 released

## References

- [https://github.com/kyverno/kyverno/security/advisories/GHSA-fr24-3hvf-393q](https://github.com/kyverno/kyverno/security/advisories/GHSA-fr24-3hvf-393q)
- [https://www.vulncheck.com/advisories/kyverno-1.11.0-before-1.19.2-memory-exhaustion-via-notary-signature-decompression](https://www.vulncheck.com/advisories/kyverno-1.11.0-before-1.19.2-memory-exhaustion-via-notary-signature-decompression)

## Related threats

- [Kyverno authorization bypass in generate rule validation](https://junglewise.ai/threats/cve-2026-124441-kyverno-before-1-19-2-contains-an-authorization-bypass)
- [Kyverno apiCall authorization bypass in namespace clamp](https://junglewise.ai/threats/cve-2026-124440-kyverno-from-1-19-1-before-1-19-2-contains-an-authorization)
- [Kyverno verifyImages signature verification bypass via cache](https://junglewise.ai/threats/cve-2026-122321-kyverno-1-18-0-before-1-19-2-contains-a-signature-verification)
- [Kyverno missing authorization in generate.clone namespace](https://junglewise.ai/threats/cve-2026-122320-kyverno-before-1-19-2-contains-a-missing-authorization)
- [Kyverno denial-of-service in In and NotIn operators](https://junglewise.ai/threats/cve-2026-122319-kyverno-before-1-19-2-contains-a-denial-of-service-vulnerability)