Memory corruption in decodeECorDsaSignature with DSA signatures (and RSA-PSS)
CVE: CVE-2021-43527
Component: nss
CWE: CWE-120
Severity: Critical
CVSS v3: 9.8/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Release date: 2021-12-01T16:00:00+00:00

A remote code execution flaw was found in the way NSS verifies certificates. This flaw allows an attacker posing as an SSL/TLS server to trigger this issue in a client application compiled with NSS when it tries to initiate an SSL/TLS connection.  Similarly, a server application compiled with NSS, which processes client certificates, can receive a malicious certificate via a client, triggering the flaw. The highest threat to this vulnerability is confidentiality, integrity, as well as system availability.

Statement: The issue is not limited to TLS. Any applications that use NSS certificate verification are vulnerable; S/MIME is impacted as well.  Similarly, a server application compiled with NSS, which processes client certificates, can receive a malicious certificate via a client.

Firefox is not vulnerable to this flaw as it uses the mozilla::pkix for certificate verification. Thunderbird is affected when parsing email with the S/MIME signature.  Thunderbird on Red Hat Enterprise Linux 8.4 and later does not need to be updated since it uses the system NSS library, but earlier Red Hat Enterprise Linux 8 extended life streams will need to update Thunderbird as well as NSS.

Remediation:
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

After installing this update, applications using NSS (for example, Firefox) must be restarted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

After installing this update, applications using NSS (for example, Firefox) must be restarted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

After installing this update, applications using NSS (for example, Firefox) must be restarted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

After installing this update, applications using NSS (for example, Firefox) must be restarted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

After installing this update, applications using NSS (for example, Firefox) must be restarted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

After installing this update, applications using NSS (for example, Firefox) must be restarted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/2974891
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/2974891
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

All running instances of Thunderbird must be restarted for the update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

After installing this update, applications using NSS (for example, Firefox) must be restarted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

After installing this update, applications using NSS (for example, Firefox) must be restarted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

All running instances of Thunderbird must be restarted for the update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

After installing this update, applications using NSS (for example, Firefox) must be restarted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

After installing this update, applications using NSS (for example, Firefox) must be restarted for this update to take effect.
Red Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update the affected package as soon as possible.