CVE-2026-78129

Infinite Loop in PKCS#5 Decryption of strongSwan

Published Sep 11, 2026 CVSS 3.1 · 5.9 Medium EPSS < 1% KEV · Not listed

Description

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

Analysis

Technical impact

The vulnerability is an infinite loop triggered during PKCS#5 decryption in strongSwan versions 4.6.2 through 6.0.7, leading to a denial of service by consuming processing resources until the system becomes unresponsive. This weakness represents a classic improper loop control flaw (CWE‑835).

Affected Systems

StrongSwan, as released by the strongSwan project, is affected for versions 4.6.2 through 6.0.7. No other vendors or products are listed in the impact data.

Risk and Exploitability

The CVSS score of 5.9 indicates moderate severity. The EPSS score is not available and the vulnerability is not currently listed in the CISA KEV catalog. Based on the description it is inferred that the attack vector is remote, leveraging network traffic that is processed by the PKCS#5 decryption routine during IPsec negotiations. An attacker who can supply malformed encrypted payloads could potentially trigger the infinite loop, exhausting CPU resources and causing service disruption.

Affected Products

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

strongSwan

unaffected

Version	Status	Constraints
`4.6.2`	affected	< 6.1.0

Configuration 1 [-]

cpe:2.3:a:strongswan:strongswan:*:*:*:*:*:*:*:*

No data.

Vendor Product Versions

Strongswan

Version	Status	Scheme	Platform
`[4.6.2,6.1.0)`	affected	semver	—

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

Upgrade to strongSwan 6.1.0 or later, as released on 2026-09-07.
If an upgrade cannot be performed immediately, temporarily disable or avoid using the PKCS#5 decryption functionality until the fix is applied.
Monitor CPU usage, system logs, and network traffic for signs of denial of service or resource exhaustion.

Generated by OpenCVE AI on September 11, 2026 at 03:16 UTC.

Tracking

Advisories

Source	ID	Title
Debian DLA	DLA-4879-1	strongswan security update
Debian DSA	DSA-6487-1	strongswan security update
Ubuntu USN	USN-8789-1	strongSwan vulnerabilities

Metrics

No CVSS v4.0

Attack Vector Network

Attack Complexity High

Privileges Required None

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploit prediction score: < 1% (0.463% probability within 30 days)

Exploitation none

Automatable no

Technical Impact partial

References

Link	Providers
https://github.com/strongswan/strongswan/releases/tag/6.1.0
https://www.strongswan.org/blog/2026/09/07/strongswan-vulnerability-(cve-2026-78129).html

History

Sep 11, 2026 3:30 PM Scoring metrics updated View changes

Type	Values Removed	Values Added
Metrics		ssvc `{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}`

Sep 11, 2026 3:45 AM Title updated View changes

Type	Values Removed	Values Added
Title		Infinite Loop in PKCS#5 Decryption of strongSwan

Sep 11, 2026 1:45 AM Description updated. First appearance in the feed. Weaknesses updated. Affected versions updated. Affected vendors updated. Added references. Scoring metrics updated View changes

Type	Values Removed	Values Added
Description		strongSwan 4.6.2 through 6.0.7 has an infinite loop in PKCS#5 decryption.
First Time appeared		Strongswan Strongswan strongswan
Weaknesses		CWE-835
CPEs		cpe:2.3:a:strongswan:strongswan::::::::
Vendors & Products		Strongswan Strongswan strongswan
References		https://github.com/strongswan/strongswan/releases/tag/6.1.0 https://www.strongswan.org/blog/2026/09/07/strongswan-vulnerability-(cve-2026-78129).html
Metrics		cvssV3_1 `{'score': 5.9, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H'}`