Security Advisory

STRONGSWAN - CVE-2021-41991, CVE-2021-45079
Published: October 31, 2022
Last Update: October 31, 2022

In October 2021 and January 2022, Strongswan.org disclosed[1, 2] vulnerabilities that could lead to denial-of-service attacks or bypass EAP authentication. These vulnerabilities could affect IPsec services in the management or data plane of ACOS devices and are addressed in this document.

Item Score
# Vulnerability ID Source Score Summary
1 CVE-2021-41991 CVSSv3 7.5 High strongswan: integer overflow when replacing certificates in cache[3]
2 CVE-2021-45079 CVSSv3 9.1 Critical strongswan: Incorrect Handling of Early EAP-Success Messages[4]
Affected Releases

The table below indicates releases of ACOS exposed to this vulnerability and ACOS releases that address them. ACOS release families not indicated below are unaffected by these vulnerabilities.

Customers using affected ACOS releases can overcome vulnerability exposures by updating to the indicated resolved release. If the table does not list a corresponding resolved or unaffected release, then no ACOS release update is currently available.

Releases Affected Releases Resolved or Unaffected
5.0.0 – 5.2.1-P5 5.2.1-P6
4.1.4-GR1 – 4.1.4-GR1-P11 4.1.4-GR1-P12
Workarounds and Mitigations


Software Updates

Software updates that address these vulnerabilities are or will be published at the following URL: https://support.a10networks.com/

Vulnerability Details

The following table shares brief descriptions for the vulnerabilities addressed in this document.

Vulnerability ID Vulnerability Description

The in-memory certificate cache in strongSwan before 5.9.4 has a remote integer overflow upon receiving many requests with different certificates to fill the cache and later trigger the replacement of cache entries. The code attempts to select a less-often-used cache entry by means of a random number generator, but this is not done correctly. Remote code execution might be a slight possibility.


In strongSwan before 5.9.5, a malicious responder can send an EAP-Success message too early without actually authenticating the client and (in the case of EAP methods with mutual authentication and EAP-only authentication for IKEv2) even without server authentication.



Modification History
Revision Date Description
1 October 31, 2022

Initial Publication

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