Description
Off-by-one error in the event_wallops function in fe-common/irc/fe-events.c in irssi 0.8.13 allows remote IRC servers to cause a denial of service (crash) via an empty command, which triggers a one-byte buffer under-read and a one-byte buffer underflow.
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 | irssi | 0.8.13-2 | — |
| Debian 13 | irssi | 0.8.13-2 | — |
| Debian 12 | irssi | 0.8.13-2 | — |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | irssi | 0.8.20-3.1 | openSUSE-SU-2024:10455-1 |
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.
Exploit-DB 1
- Irssi 0.8.13 - 'WALLOPS' Message Off-by-One Heap Memory Corruption EDB-33041 · dos · May 15, 2009 · verified
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Advisories 1
- openSUSE-SU-2024:10455-1 irssi-0.8.20-3.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
References
- http://xorl.wordpress.com/2009/05/28/irssi-event_wallops-off-by-one-readwrite/
- 1022410 vdb-entry
- [oss-security] 20090529 CVE Request (irssi) mailing-list
- 35399 vdb-entry
- http://www.irssi.org/ChangeLog
- FEDORA-2009-7012 vendor-advisory
- http://bugs.irssi.org/index.php?do=details&task_id=662
- 35685 third-party-advisory
- ADV-2009-1596 vdb-entry
- SUSE-SR:2009:012 vendor-advisory
- USN-800-1 vendor-advisory
- 35812 third-party-advisory
- MDVSA-2009:133 vendor-advisory
- irssi-eventwallops-dos(51184) vdb-entry
- 36152 third-party-advisory