Description
The search_make_new function in evdns.c in libevent before 2.1.6-beta allows attackers to cause a denial of service (out-of-bounds read) via an empty hostname.
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 | libevent | 2.0.21-stable-3 | — |
| Debian 13 | libevent | 2.0.21-stable-3 | — |
| Debian 12 | libevent | 2.0.21-stable-3 | — |
| Debian 8 | libevent | 2.0.21-stable-2+deb8u1 | DSA-3789-1 |
| Debian 7 | libevent | 2.0.19-stable-3+deb7u2 | DLA-824-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 16.04 LTS | firefox | 53.0+build6-0ubuntu0.16.04.1 | — |
| Ubuntu 16.04 LTS | libevent | 2.0.21-stable-2ubuntu0.16.04.1 | USN-3228-1 |
| Ubuntu 16.04 LTS | thunderbird | 1:52.1.1+build1-0ubuntu0.16.04.1 | USN-3278-1 |
| Ubuntu 14.04 LTS | firefox | 53.0+build6-0ubuntu0.14.04.1 | — |
| Ubuntu 14.04 LTS | libevent | 2.0.21-stable-1ubuntu1.14.04.2 | USN-3228-1 |
| Ubuntu 14.04 LTS | thunderbird | 1:52.1.1+build1-0ubuntu0.14.04.1 | USN-3278-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 7 | firefox | 52.1.0-2.el7_3 | RHSA-2017:1106 |
| RHEL 7 | thunderbird | 52.1.0-1.el7_3 | RHSA-2017:1201 |
| RHEL 6 | firefox | 52.1.0-2.el6_9 | RHSA-2017:1104 |
| RHEL 6 | thunderbird | 52.1.0-1.el6_9 | RHSA-2017:1201 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 12 SP3 | libevent | 2.0.21-6.3.1 | SUSE-SU-2018:0200-1 |
| SLES 12 SP2 | libevent | 2.0.21-6.3.1 | SUSE-SU-2018:0200-1 |
| SLES 11 SP4 | libevent | 1.4.5-24.24.3.1 | SUSE-SU-2018:0263-1 |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 12 SP3 | libevent | 2.0.21-6.3.1 | SUSE-SU-2018:0200-1 |
| SLES for SAP 12 SP2 | libevent | 2.0.21-6.3.1 | SUSE-SU-2018:0200-1 |
| SLES for SAP 11 SP4 | libevent | 1.4.5-24.24.3.1 | SUSE-SU-2018:0263-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | libevent | 2.1.8-r0 | — |
| Alpine v3.23 | libevent | 2.1.8-r0 | — |
| Alpine v3.22 | libevent | 2.1.8-r0 | — |
| Alpine v3.21 | libevent | 2.1.8-r0 | — |
| Alpine v3.20 | libevent | 2.1.8-r0 | — |
Show 18 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | libevent | 2.1.8-r0 | — |
| Alpine v3.18 | libevent | 2.1.8-r0 | — |
| Alpine v3.17 | libevent | 2.1.8-r0 | — |
| Alpine v3.16 | libevent | 2.1.8-r0 | — |
| Alpine v3.15 | libevent | 2.1.8-r0 | — |
| Alpine v3.14 | libevent | 2.1.8-r0 | — |
| Alpine v3.13 | libevent | 2.1.8-r0 | — |
| Alpine v3.12 | libevent | 2.1.8-r0 | — |
| Alpine v3.11 | libevent | 2.1.8-r0 | — |
| Alpine v3.10 | libevent | 2.1.8-r0 | — |
| Alpine v3.9 | libevent | 2.1.8-r0 | — |
| Alpine v3.8 | libevent | 2.1.8-r0 | — |
| Alpine v3.7 | libevent | 2.1.8-r0 | — |
| Alpine v3.6 | libevent | 2.1.8-r0 | — |
| Alpine v3.5 | libevent | 2.0.22-r2 | — |
| Alpine v3.4 | libevent | 2.0.22-r1 | — |
| Alpine v3.3 | libevent | 2.0.22-r1 | — |
| Alpine v3.2 | libevent | 2.0.22-r1 | — |
Advisories 9
- USN-3278-1 thunderbird vulnerabilities Ubuntu Security Notices (USN) · Oct 27, 2026
- RHSA-2017:1201 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Oct 17, 2026
- RHSA-2017:1104 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Oct 17, 2026
- RHSA-2017:1106 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Oct 17, 2026
- USN-3228-1 libevent vulnerabilities Ubuntu Security Notices (USN) · Apr 22, 2026
- DLA-824-1 libevent - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DSA-3789-1 libevent - security update Debian Security (DSA / DLA) · Mar 9, 2026
- SUSE-SU-2018:0200-1 Security update for libevent SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2018:0263-1 Security update for libevent SUSE / openSUSE Security Updates · Feb 4, 2026
References
- 96014 vdb-entry
- RHSA-2017:1106 vendor-advisory
- DSA-3789 vendor-advisory
- [oss-security] 20170202 Re: Bugs fixed in libevent 2.1.6 mailing-list
- GLSA-201705-01 vendor-advisory
- https://github.com/libevent/libevent/issues/332
- https://github.com/libevent/libevent/commit/ec65c42052d95d2c23d1d837136d1cf1d9ecef9e
- [oss-security] 20170131 Bugs fixed in libevent 2.1.6 mailing-list
- 1038320 vdb-entry
- https://github.com/libevent/libevent/blob/release-2.1.6-beta/ChangeLog
- RHSA-2017:1104 vendor-advisory
- RHSA-2017:1201 vendor-advisory