Description
config/filter.d/cyrus-imap.conf in the cyrus-imap filter in Fail2ban before 0.8.11 allows remote attackers to trigger the blocking of an arbitrary IP address via a crafted e-mail address that matches an improperly designed regular expression.
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 | fail2ban | 0.8.11-1 | — |
| Debian 13 | fail2ban | 0.8.11-1 | — |
| Debian 12 | fail2ban | 0.8.11-1 | — |
| Debian 7 | fail2ban | 0.8.6-3wheezy3 | DSA-2979-1 |
| Debian 6.0 | fail2ban | 0.8.4-3+squeeze3 | DLA-0021-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | fail2ban | 0.9.5-1.1 | openSUSE-SU-2024:10347-1 |
Advisories 3
- DSA-2979-1 fail2ban - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DLA-0021-1 fail2ban - security update Debian Security (DSA / DLA) · Mar 9, 2026
- openSUSE-SU-2024:10347-1 SuSEfirewall2-fail2ban-0.9.5-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
References
- VU#686662 third-party-advisory
- https://github.com/fail2ban/fail2ban/commit/bd175f026737d66e7110868fb50b3760ff75e087
- openSUSE-SU-2014:0348 vendor-advisory
- DSA-2979 vendor-advisory