Debian Security Advisory

DSA-4989-1 strongswan -- security update

Date Reported:
18 Oct 2021
Affected Packages:
Security database references:
In Mitre's CVE dictionary: CVE-2021-41990, CVE-2021-41991.
More information:

Researchers at the United States of America National Security Agency (NSA) identified two denial of services vulnerability in strongSwan, an IKE/IPsec suite.

  • CVE-2021-41990

    RSASSA-PSS signatures whose parameters define a very high salt length can trigger an integer overflow that can lead to a segmentation fault.

    Generating a signature that bypasses the padding check to trigger the crash requires access to the private key that signed the certificate. However, the certificate does not have to be trusted. Because the gmp and the openssl plugins both check if a parsed certificate is self-signed (and the signature is valid), this can e.g. be triggered by an unrelated self-signed CA certificate sent by an initiator.

  • CVE-2021-41991

    Once the in-memory certificate cache is full it tries to randomly replace lesser used entries. Depending on the generated random value, this could lead to an integer overflow that results in a double-dereference and a call using out-of-bounds memory that most likely leads to a segmentation fault.

    Remote code execution can't be ruled out completely, but attackers have no control over the dereferenced memory, so it seems unlikely at this point.

For the oldstable distribution (buster), these problems have been fixed in version 5.7.2-1+deb10u1.

For the stable distribution (bullseye), these problems have been fixed in version 5.9.1-1+deb11u1.

We recommend that you upgrade your strongswan packages.

For the detailed security status of strongswan please refer to its security tracker page at: