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Ubuntu SSSD Denial of Service Vulnerability USN-8718-1 CVE-2026

Linuxsecurity •LinuxSecurity Advisories • September 3, 2026

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SSSD could be made to crash if it received specially crafted input. Software Description: - sssd: System Security Services Daemon Details: It was discovered that SSSD did not properly validate authentication token lengths when processing PAM responder requests. A local attacker could possibly use this issue to cause SSSD to crash, resulting in a denial of service.

SSSD could be made to crash if it received specially crafted input.

Software Description:

- sssd: System Security Services Daemon

It was discovered that SSSD did not properly validate authentication token

lengths when processing PAM responder requests. A local attacker could

possibly use this issue to cause SSSD to crash, resulting in a denial of

The problem can be corrected by updating your system to the following package versions: Ubuntu 26.04 LTS sssd-common 2.12.0-1ubuntu5.4 Ubuntu 24.04 LTS sssd-common 2.9.4-1.1ubuntu6.8 Ubuntu 22.04 LTS sssd-common 2.6.3-1ubuntu3.9 Ubuntu 20.04 LTS sssd-common 2.2.3-3ubuntu0.13+esm1 Available with Ubuntu Pro Ubuntu 18.04 LTS sssd-common 1.16.1-1ubuntu1.8+esm1 Available with Ubuntu Pro Ubuntu 16.04 LTS sssd-common 1.13.4-1ubuntu1.15+esm1 Available with Ubuntu Pro After a standard system update you need to restart sssd to make all the necessary changes.

Ubuntu Security Notice USN-8718-1

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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

Extracted Entities

Ubuntu SSSD Denial of Service Vulnerability USN-8718-1 CVE-2026

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Extracted Entities

Attack Types (1)

Companies (1)

CWE Weaknesses (1)

Platforms (1)