cert-manager ha a potential slowdown / DoS when parsing specially crafted PEM inputs

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

6.9 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N · score source

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Impact cert-manager packages which call the standard library pem.Decode() function can take a long time to process specially crafted invalid PEM data. If an attacker is able to modify PEM data which cert-manager reads (e.g. in a Secret resource), they may be able to use large amounts of CPU in the cert-manager controller pod to effectively create a denial-of-service (DoS) vector for cert-manager in the cluster. Secrets are limited in size to 1MiB, which reduces the impact of this issue; it was discovered through an ~856kB fuzz test input which causes pem.Decode to take roughly 750ms to reject the input on an M2 Max Macbook Pro. By way of comparison, a valid PEM-encoded 4096-bit RSA key takes roughly 70µs to parse on the same machine. Given the required size of PEM data needed to present a realistic DoS vector, an attacker would need to create or insert many different large sized resources in the cluster, and so the best secondary defense is to ensure that sensible limits are placed…

Published by the source

20 Nov 2024, 20:48 UTC

Last modified by the source

5 Jun 2026, 21:21 UTC

Source last checked

26 Oct 2026, 15:23 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-r4pg-vg54-wxx4

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# Patch Next advisory brief: GHSA-r4pg-vg54-wxx4

Advisory: cert-manager ha a potential slowdown / DoS when parsing specially crafted PEM inputs
IDs: GHSA-r4pg-vg54-wxx4
Record: https://patchnext.com/advisories/ghsa-r4pg-vg54-wxx4 (revision 1, source checked 26 Oct 2026, 15:23 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/cert-manager/cert-manager 1.16.2, 1.15.4, 1.12.14. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/cert-manager/cert-manager: affected < 1.12.14; >= 1.13.0-alpha.0, < 1.15.4; >= 1.16.0-alpha.0, < 1.16.2; fixed in 1.12.14, 1.16.2, 1.15.4

## Suggested inspection (read-only)
- Go github.com/cert-manager/cert-manager: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/cert-manager/cert-manager.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-r4pg-vg54-wxx4 (GitHub-reviewed advisory GHSA-r4pg-vg54-wxx4 lists affected ranges: Go github.com/cert-manager/cert-manager >=0 =1.13.0-alpha.0 =1.16.0-alpha.0 <1.16.2)

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