strongSwan: Improper Enforcement of Behavioral Workflow
CVE-2026-78135 is a high-severity improper enforcement of behavioral workflow vulnerability in strongSwan, with a CVSS 3.1 base score of 7.3 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 6.1.0 as the first without the flaw, so updating strongSwan to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.42% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update strongSwan to 6.1.0 or a later version.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| strongSwan | strongSwan | 5.9.7 up to, but not including, 6.1.0 | 6.1.0 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- LowSome restricted data can be read.
- Integrity
- LowLimited modification of data is possible.
- Availability
- LowPerformance or availability is reduced.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 5.6 | Medium | CNA (mitre.org) |
| CVSS 3.1 | 7.3 | High | NVD |
Official description
libcharon in strongSwan 5.9.7 through 6.0.7 mishandles behavioral workflow in the IKEv2 state machine. Because CREATE_CHILD_SA requests are mishandled, there can be an authentication bypass.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Enforcement of Behavioral Workflow
The product supports a session in which more than one behavior must be performed by an actor, but it does not properly ensure that the actor performs the behaviors in the required sequence or timeframe.
More Improper Enforcement of Behavioral Workflow vulnerabilities (CWE-841)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Other vulnerabilities in strongSwan
- 7.1 High severity
- 7.5 High severity
- 7.5 High severity
- 8.1 High severity
- 9.8 Critical severity
- 9.8 Critical severity
Recent Improper Enforcement of Behavioral Workflow vulnerabilities
- 6.5 Medium severity
- 8.7 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 9.1 Critical severity
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