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CVE-2025-54363VulnerabilityPublished Updated

CVE-2025-54363: Microsoft Knack · ReDoS

Affects Microsoft KnackSource CVE Database V5

0

Not known to be exploited · CVSS 6.9 Medium.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 4.0 base score
6.9Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.4% chance of exploitation in 30 days – higher than 35% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 20 Aug 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 2026-10-26.

What to do

Affected software

ProductAffectedFixed in
Microsoft KnackAffected
  • =0.12.0
Fixed in–

AI-suggested

To mitigate this vulnerability, European organizations should: 1) Immediately audit their environments to identify usage of Microsoft Knack 0.12.0, particularly within Azure CLI or any custom tooling. 2) Restrict or sanitize any input that could influence docstring content processed by the knack.introspection module to prevent injection of maliciously crafted strings. 3) Implement resource limits and monitoring on CPU usage for processes running Azure CLI or related tools to detect abnormal consumption patterns indicative of ReDoS attacks. 4) Apply strict access controls to limit who can execute or modify scripts that utilize Microsoft Knack, reducing the risk of local exploitation. 5) Monitor vendor communications for patches or updates addressing this vulnerability and plan prompt deployment once available. 6) Consider isolating or sandboxing environments where untrusted code or inputs are processed to contain potential impact. 7) Educate developers and administrators about the risks of ReDoS and encourage secure coding practices around regular expressions.

Description

Microsoft Knack 0.12.0 allows Regular expression Denial of Service (ReDoS) in the knack.introspection module.extract_full_summary_from_signature employs an inefficient regular expression pattern: "\s(:param)\s+(.+?)\s:(.*)" that is susceptible to catastrophic backtracking when processing crafted docstrings containing a large volume of whitespace without a terminating colon. An attacker who can control or inject docstring content into affected applications can trigger excessive CPU consumption. This software is used by Azure CLI.

References

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