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VulnerabilityPublished Updated

CVE-2024-39844: znc · Code Injection

Affects zncSource CVE Database V5

0

Not known to be exploited · CVSS 9.8 Critical : upgrade to 1.9.1 as a priority.

Data as of 26 Oct 2026, 12:54 UTC

CVSS 3.1 base score
9.8Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
3.8% chance of exploitation in 30 days – higher than 90% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 1.9.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 3 Jul 2024

  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

Upgrade znc/znc to 1.9.1.

Affected software

ProductAffectedFixed in
GitHubznc/zncpkg:github/znc/zncOther threatsAffected
  • <1.9.1
Fixed in
  • 1.9.1

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

AI-suggested

Organizations should immediately upgrade ZNC to version 1.9.1 or later, where this vulnerability has been addressed. If upgrading is not immediately feasible, disabling the modtcl module is a practical interim mitigation to prevent exploitation via the vulnerable code path. Network-level controls such as restricting access to ZNC services to trusted IP ranges and implementing firewall rules to limit exposure of IRC ports can reduce attack surface. Monitoring IRC logs for unusual KICK commands or suspicious activity may help detect attempted exploitation. Additionally, applying strict input validation and sanitization in custom scripts or modules interacting with ZNC can reduce risk. Regularly auditing and updating IRC-related infrastructure and maintaining an incident response plan for potential compromises are recommended.

Description

In ZNC before 1.9.1, remote code execution can occur in modtcl via a KICK.

References

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