Parsing JSON serialized payload without protected field can lead to segfault

Exploitation

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

CVSS

4.3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L

EPSS

• CVE-2024-21664: 0.86% estimated exploitation activity in the next 30 days; percentile 58.68 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary Calling jws.Parse with a JSON serialized payload where the signature field is present while protected is absent can lead to a nil pointer dereference. Details This seems to also affect other functions that calls Parse internally, like jws.Verify. My understanding of these functions from the docs is that they are supposed to fail gracefully on invalid input and don't require any prior validation. Based on the stack trace in the PoC, the issue seems to be that the processing done in jws/message.go:UnmarshalJSON() assumes that if a signature field is present, then a protected field is also present. If this is not the case, then the subsequent call to getB64Value(sig.protected) will dereference sig.protected, which is nil. PoC Reproducer: Result: Impact The vulnerability can be used to crash / DOS a system doing JWS verification.

Published by the source

9 Jan 2024, 16:18 UTC

Last modified by the source

24 Jan 2024, 16:16 UTC

Source last checked

26 Oct 2026, 15:03 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-pvcr-v8j8-j5q3

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# Patch Next advisory brief: CVE-2024-21664

Advisory: Parsing JSON serialized payload without protected field can lead to segfault
IDs: CVE-2024-21664, GHSA-pvcr-v8j8-j5q3
Record: https://patchnext.com/advisories/cve-2024-21664 (revision 1, source checked 26 Oct 2026, 15:03 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/lestrrat-go/jwx/v2 2.0.19; github.com/lestrrat-go/jwx 1.2.28. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/lestrrat-go/jwx/v2: affected < 2.0.19; fixed in 2.0.19
- Go github.com/lestrrat-go/jwx: affected >= 1.0.8, < 1.2.28; fixed in 1.2.28

## Suggested inspection (read-only)
- Go github.com/lestrrat-go/jwx/v2: check the installed version with your package manager.
- Go github.com/lestrrat-go/jwx: 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/lestrrat-go/jwx/v2, github.com/lestrrat-go/jwx.
- 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-pvcr-v8j8-j5q3 (GitHub-reviewed advisory GHSA-pvcr-v8j8-j5q3 lists affected ranges: Go github.com/lestrrat-go/jwx/v2 >=0 =1.0.8 <1.2.28)

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