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VulnerabilityPublished Updated

CVE-2025-45311: fail2ban-client · Incorrect Privilege Assignment

Affects fail2ban-clientSource CVE Database V5

0

Not known to be exploited · CVSS 8.8 High.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score
8.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.3% chance of exploitation in 30 days – higher than 30% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 26 Nov 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
GitHubfail2ban/fail2ban-clientpkg:github/fail2ban/fail2ban-clientOther threatsAffected
  • =0.11.2
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

To mitigate CVE-2025-45311, European organizations should implement the following specific measures: 1) Audit and minimize sudo privileges, ensuring only trusted users have sudo access and that their permissions are as restrictive as possible, ideally avoiding unnecessary access to fail2ban-client commands. 2) Employ sudoers file configurations to limit commands executable by users with sudo rights, explicitly restricting fail2ban-client usage or its ability to trigger arbitrary root commands. 3) Monitor fail2ban configurations and triggered actions to detect unusual or unauthorized rule executions. 4) Consider deploying additional monitoring and alerting on privilege escalations and fail2ban-client invocations. 5) If feasible, run fail2ban with the least privileges necessary or within containerized or sandboxed environments to limit root-level command execution scope. 6) Stay updated on vendor advisories for patches or updates addressing this issue and apply them promptly once available. 7) Conduct regular security training and awareness for administrators managing sudo privileges and fail2ban configurations to prevent misconfigurations.

Description

Insecure permissions in fail2ban-client v0.11.2 allows attackers with limited sudo privileges to perform arbitrary operations as root. NOTE: this is disputed by multiple parties because the action for a triggered rule can legitimately be an arbitrary operation as root. Thus, the software is behaving in accordance with its intended privilege model.

References

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