What is CVE-2026-78129?

CVE-2026-78129 is a medium-severity vulnerability in Strongswan, classified under Loop with Unreachable Exit Condition (Infinite Loop). CVSS score: 5.9/10. Published 2026-09-11.

How severe is CVE-2026-78129?

Medium severity. CVSS v3 base score is 5.9 out of 10.

Vulnerability in Strongswan

CVE-2026-78129

strongSwan 4.6.2 through 6.0.7 has an infinite loop in PKCS#5 decryption.

Published 2026-09-11 · last modified 2026-09-14.

CVSS v3 metric

CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.005 (39.9th percentile), scored 2026-10-26.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 40th percentile — 39.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.004 · newest: 0.005 · change: +0.001

Affected products

Strongswan

Weakness classification (CWE)

CWE-835 — Loop with Unreachable Exit Condition (Infinite Loop)

References

github.com/strongswan/strongswan/releases/tag/6.1.0 (Patch, Release Notes, Vendor Advisory)
www.strongswan.org/blog/2026/09/07/strongswan-vulnerability-(cve-2026-78129).ht… (Mitigation, Vendor Advisory)

Frequently asked questions

What is CVE-2026-78129?: CVE-2026-78129 is a medium-severity vulnerability in Strongswan, classified under Loop with Unreachable Exit Condition (Infinite Loop). CVSS score: 5.9/10. Published 2026-09-11.
How severe is CVE-2026-78129?: Medium severity. CVSS v3 base score is 5.9 out of 10.