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Ubuntu 26.04 LTS SSSD Crash Due to Smartcard Interaction USN-8672

Linuxsecurity •LinuxSecurity Advisories • September 2, 2026

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SSSD could be made to crash if it interacted with a smartcard or Yubikey Software Description: - sssd: System Security Services Daemon Details: It was discovered that the SSSD PAM responder may crash if a physically proximate attacker manipulates a smartcard or Yubikey. Non-malicious physically proximate users may not be able to log in depending upon the details of their legitimate smartcard or Yubikey.

SSSD could be made to crash if it interacted with a smartcard or Yubikey

Software Description:

- sssd: System Security Services Daemon

It was discovered that the SSSD PAM responder may crash if a physically

proximate attacker manipulates a smartcard or Yubikey. Non-malicious

physically proximate users may not be able to log in depending upon the

details of their legitimate smartcard or Yubikey.

The problem can be corrected by updating your system to the following package versions: Ubuntu 26.04 LTS libpam-sss 2.12.0-1ubuntu5.3 sssd-common 2.12.0-1ubuntu5.3 Ubuntu 24.04 LTS libpam-sss 2.9.4-1.1ubuntu6.7 sssd-common 2.9.4-1.1ubuntu6.7 Ubuntu 22.04 LTS libpam-sss 2.6.3-1ubuntu3.8 sssd-common 2.6.3-1ubuntu3.8 After a standard system update you need to restart sssd to make all the necessary changes.

Ubuntu Security Notice USN-USN-8672-1

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This article is one source in a clustered incident — the cluster page carries the summary, timeline and every other outlet covering it.

SSSD Vulnerabilities in Ubuntu Lead to Potential Denial of Service Recent vulnerabilities in the System Security Services Daemon (SSSD) have been identified in Ubuntu versions 22.04, 24.04, and 26.04 LTS. The first vulnerability allows a physically proximate attacker to crash SSSD through manipulation of smartcards or Yubikeys, affecting user login capabilities. The second vulnerability involves improper validation of authentication token lengths, which could also lead to SSSD crashes and denial of service. Users of affected systems are advised to update their packages to the latest versions to mitigate these risks. The vulnerabilities have been assigned USN-8672-1 and USN-8718-1 respectively. After applying updates, a restart of SSSD is required to implement the changes. No active exploitation has been reported yet, but the vulnerabilities pose significant risks to system availability. 3 sources 45

Ubuntu 26.04 LTS SSSD Crash Due to Smartcard Interaction USN-8672

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