Description
Irssi before 0.8.21 allows remote attackers to cause a denial of service (out-of-bounds read and crash) via a string containing a formatting sequence (%[) without a closing bracket (]).
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 | 0.8.21-1 | — |
| Debian 13 | irssi | 0.8.21-1 | — |
| Debian 12 | irssi | 0.8.21-1 | — |
| Debian 7 | irssi | 0.8.15-5+deb7u4 | DLA-1217-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 16.04 LTS | irssi | 0.8.19-1ubuntu1.3 | USN-3184-1 |
| Ubuntu 14.04 LTS | irssi | 0.8.15-5ubuntu3.1 | USN-3184-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | irssi | 1.2.3-2.4 | openSUSE-SU-2024:10865-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.5 | irssi | 0.8.21-r0 | — |
| Alpine v3.4 | irssi | 0.8.21-r0 | — |
| Alpine v3.3 | irssi | 0.8.21-r0 | — |
| Alpine v3.2 | irssi | 0.8.21-r0 | — |
Advisories 3
- USN-3184-1 irssi vulnerabilities Ubuntu Security Notices (USN) · Apr 22, 2026
- DLA-1217-1 irssi - security update Debian Security (DSA / DLA) · Mar 9, 2026
- openSUSE-SU-2024:10865-1 irssi-1.2.3-2.4 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
References
- [debian-lts-announce] 20171223 [SECURITY] [DLA 1217-1] irssi security update mailing-list
- 96581 vdb-entry
- https://blog.fuzzing-project.org/55-Fuzzing-Irssi-with-Perl-Scripts.html
- https://irssi.org/security/irssi_sa_2017_01.txt
- [oss-security] 20170112 CVE Request: Irssi out of bounds read in format string mailing-list
- [oss-security] 20170112 Re: CVE Request: Irssi out of bounds read in format string mailing-list