Description
In ZNC before 1.9.1, remote code execution can occur in modtcl via a KICK.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | znc | 1.9.1-1 | — |
| Debian 13 | znc | 1.9.1-1 | — |
| Debian 12 | znc | 1.8.2-3.1+deb12u1 | DSA-5725-1 |
| Debian 11 | znc | 1.8.2-2+deb11u1 | DSA-5725-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 22.04 LTS | znc | 1.8.2-2ubuntu0.1 | USN-6990-1 |
Show 5 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 24.04 LTS | znc | 1.9.0-2ubuntu0.1~esm2 | USN-6990-1 |
| Ubuntu Pro 20.04 LTS | znc | 1.7.5-4ubuntu0.1~esm2 | USN-6990-1 |
| Ubuntu Pro 18.04 LTS | znc | 1.6.6-1ubuntu0.2+esm2 | USN-6990-1 |
| Ubuntu Pro 16.04 LTS | znc | 1.6.3-1ubuntu0.2+esm2 | USN-6990-1 |
| Ubuntu Pro 14.04 LTS | znc | 1.2-3ubuntu0.1+esm3 | USN-6990-1 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SUSE Package Hub 15 SP6 | znc | 1.9.1-bp156.2.3.1 | openSUSE-SU-2024:0203-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | znc | 1.9.1-1.1 | openSUSE-SU-2024:14115-1 |
| openSUSE Leap 15.6 | znc | 1.9.1-bp156.2.3.1 | openSUSE-SU-2024:0203-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | znc | 1.9.1-r0 | — |
| Alpine v3.23 | znc | 1.9.1-r0 | — |
| Alpine v3.22 | znc | 1.9.1-r0 | — |
| Alpine v3.21 | znc | 1.9.1-r0 | — |
| Alpine v3.20 | znc | 1.9.1-r0 | — |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
Third-party code, not reviewed by us. Public PoCs are sometimes fake or contain malware. Read the code first and run it only in an isolated lab, against systems you are authorised to test.
GitHub 1 repository
-
ph1ns/CVE-2024-39844 ★ 1 · Jul 3, 2024
CVE-2024-39844 (ZNC < 1.9.1 modtcl RCE)
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Advisories 4
- USN-6990-1 znc vulnerability Ubuntu Security Notices (USN) · Jun 29, 2026
- DSA-5725-1 znc - security update Debian Security (DSA / DLA) · Mar 9, 2026
- openSUSE-SU-2024:0203-1 Security update for znc SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:14115-1 znc-1.9.1-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026