Description
The try_parse_v4_netmask function in hostmask.c in IRCD-Hybrid before 8.0.6 does not properly validate masks, which allows remote attackers to cause a denial of service (crash) via a mask that causes a negative number to be parsed.
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 13 | ircd-hybrid | 1:7.2.2.dfsg.2-10 | — |
| Debian 12 | ircd-hybrid | 1:7.2.2.dfsg.2-10 | — |
| Debian 6.0 | ircd-hybrid | 1:7.2.2.dfsg.2-6.2+squeeze1 | DSA-2618-1 |
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
- ircd-hybrid 8.0.5 - Denial of Service EDB-24951 · dos · Apr 12, 2013
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Advisories 1
- DSA-2618-1 ircd-hybrid - denial of service Debian Security (DSA / DLA) · Mar 9, 2026
References
- DSA-2618 vendor-advisory
- 52106 third-party-advisory
- [oss-security] 20130129 ircd-hybrid: Denial of service vulnerability in hostmask.c:try_parse_v4_netmask() mailing-list
- MDVSA-2013:093 vendor-advisory
- 57610 vdb-entry
- http://svn.ircd-hybrid.org:8000/viewcvs.cgi/ircd-hybrid/trunk/src/hostmask.c?r1=1786&r2=1785&pathrev=1786
- 51948 third-party-advisory
- ircdhybrid-tryparsev4netmask-dos(81695) vdb-entry
- https://wiki.mageia.org/en/Support/Advisories/MGASA-2013-0055
- 89623 vdb-entry
- 24951 exploit
- http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=699267