CVE-2026-78133

Use-After-Free in strongSwan IKEv2 Rekeying Collision Handling

Published Sep 11, 2026 CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed

Description

libcharon in strongSwan 6.0.0 through 6.0.7 has a use-after-free in IKEv2 rekeying collision handling.

Analysis

Technical impact

The vulnerability is a use‑after‑free bug located in the libcharon component of strongSwan 6.0.0 through 6.0.7. The flaw manifests during IKEv2 rekeying when a rekey collision occurs. If exploited, an attacker could corrupt memory, potentially leading to arbitrary code execution or a denial of service. The immediate risk is the loss of confidentiality, integrity, or availability of the VPN connection.

Affected Systems

The affected product is strongSwan, specifically the libcharon module. Versions 6.0.0 through 6.0.7 are susceptible. All installations of strongSwan within these releases should be evaluated for exposure.

Risk and Exploitability

The CVSS score of 7.5 reflects a high severity vulnerability. No EPSS score is available, but the lack of attribution to CISA KEV indicates no confirmed exploitable exploits are publicly known yet. Nevertheless, the flaw can be triggered over the network by manipulating IKEv2 traffic, implying a network‑level attack vector. Administrators should consider the risk high until a patch is applied.

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
`6.0.0`	affected	< 6.1.0

Configuration 1 [-]

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

No data.

Vendor Product Versions

Strongswan

Version	Status	Scheme	Platform
`[6.0.0,6.1.0)`	affected	semver	—

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

Update strongSwan to version 6.1.0 or later, which contains the fix.
Restart the strongSwan service to ensure the new binaries are in use.
Limit IKEv2 traffic to trusted peers by updating firewall rules until the patch is deployed.

Generated by OpenCVE AI on September 11, 2026 at 05:07 UTC.

Tracking

Advisories

Source	ID	Title
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 Low

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

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% (0.466% probability within 30 days)

Exploitation none

Automatable no

Technical Impact total

References

Link	Providers
https://github.com/strongswan/strongswan/releases/tag/6.1.0
https://www.strongswan.org/blog/2026/09/07/strongswan-vulnerability-(cve-2026-78133).html

History

Sep 11, 2026 11:45 PM Scoring metrics updated View changes

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

Sep 11, 2026 5:30 AM Title updated View changes

Type	Values Removed	Values Added
Title		Use-After-Free in strongSwan IKEv2 Rekeying Collision Handling

Sep 11, 2026 2:00 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		libcharon in strongSwan 6.0.0 through 6.0.7 has a use-after-free in IKEv2 rekeying collision handling.
First Time appeared		Strongswan Strongswan strongswan
Weaknesses		CWE-416
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-2026-78133).html
Metrics		cvssV3_1 `{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}`