CVE catalog
CVE-2026-63387
Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent has an off-by-one stack buffer overflow in evdns.c when dnsname_to_labels formats a name-bearing DNS record at the
- Severity
- High · CVSS 8.6
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H - Published
- Updated
- Source
- [NVD] · [CVE record]
- EPSS
- 0.42% · Oct 25, 2026
Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent has an off-by-one stack buffer overflow in evdns.c when dnsname_to_labels formats a name-bearing DNS record at the end of the 64 KB stack buffer allocated by evdns_server_request_format_response. The final-label check permits j plus label_len plus one to equal buf_len, after which the terminating null byte is written to buf[buf_len]. A crafted DNS server response containing PTR, CNAME, MX, NS, or SOA data can trigger the one-byte out-of-bounds write and crash or corrupt the process. This issue is fixed in versions 2.1.13 and 2.2.2-alpha.
Vulnerable and fixed packages
Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.
| Distribution | Package | Release | Version | Status |
|---|---|---|---|---|
| Debian | libevent | sid | 2.1.13-stable-1 | fixed |
| Debian | libevent | forky | 2.1.13-stable-1 | fixed |
| Debian | libevent | trixie | 2.1.12-stable-10 | vulnerable |
| Debian | libevent | trixie-security | 2.1.13-stable-1~deb13u1 | fixed |
| Debian | libevent | bookworm | 2.1.12-stable-8 | vulnerable |
| Debian | libevent | bookworm-security | 2.1.12-stable-8+deb12u1 | fixed |
| Ubuntu | libevent | noble | 2.1.12-stable-9ubuntu2.2 | fixed |
| Ubuntu | libevent-2.1-7t64 | noble | 2.1.12-stable-9ubuntu2.2 | fixed |
| Ubuntu | libevent-core-2.1-7t64 | noble | 2.1.12-stable-9ubuntu2.2 | fixed |
| Ubuntu | libevent-dev | noble | 2.1.12-stable-9ubuntu2.2 | fixed |
| Ubuntu | libevent-extra-2.1-7t64 | noble | 2.1.12-stable-9ubuntu2.2 | fixed |
| Ubuntu | libevent-openssl-2.1-7t64 | noble | 2.1.12-stable-9ubuntu2.2 | fixed |
| Ubuntu | libevent-pthreads-2.1-7t64 | noble | 2.1.12-stable-9ubuntu2.2 | fixed |
| Ubuntu | libevent | pro | 2.1.8-stable-4build1 | vulnerable |
| Ubuntu | libevent | pro | 2.1.11-stable-1~exp0 | vulnerable |
| Ubuntu | libevent | pro | 2.1.11-stable-1 | vulnerable |
| Ubuntu | libevent | pro | 2.1.11-stable-1ubuntu0.1~esm1 | vulnerable |
| Ubuntu | libevent | pro | 2.1.11-stable-1ubuntu0.1~esm2 | fixed |
| Ubuntu | libevent | 22.04 | 2.1.12-stable-1 | vulnerable |
| Ubuntu | libevent | 22.04 | 2.1.12-stable-1build1 | vulnerable |
| Ubuntu | libevent | 22.04 | 2.1.12-stable-1build2 | vulnerable |
| Ubuntu | libevent | 22.04 | 2.1.12-stable-1build3 | vulnerable |
| Ubuntu | libevent | 22.04 | 2.1.12-stable-1ubuntu0.1 | vulnerable |
| Ubuntu | libevent | 22.04 | 2.1.12-stable-1ubuntu0.2 | fixed |
| Ubuntu | libevent | 24.04 | 2.1.12-stable-9 | vulnerable |
| Ubuntu | libevent | 24.04 | 2.1.12-stable-9ubuntu2 | vulnerable |
| Ubuntu | libevent | 24.04 | 2.1.12-stable-9ubuntu2.1 | vulnerable |
| Ubuntu | libevent | 24.04 | 2.1.12-stable-9ubuntu2.2 | fixed |
| Ubuntu | libevent | 26.04 | 2.1.12-stable-10build1 | vulnerable |
| Ubuntu | libevent | 26.04 | 2.1.12-stable-10build2 | vulnerable |
| Ubuntu | libevent | 26.04 | 2.1.12-stable-10ubuntu0.1 | vulnerable |
| Ubuntu | libevent | 26.04 | 2.1.12-stable-10ubuntu0.2 | fixed |
| Ubuntu | libevent | pro | 2.1.8-stable-4build1 | vulnerable |
| Ubuntu | libevent | pro | 2.1.11-stable-1~exp0 | vulnerable |
| Ubuntu | libevent | pro | 2.1.11-stable-1 | vulnerable |
| Ubuntu | libevent | pro | 2.1.11-stable-1ubuntu0.1~esm1 | vulnerable |
| Ubuntu | libevent | pro | 2.1.11-stable-1ubuntu0.1~esm2 | vulnerable |
| Ubuntu | libevent | 22.04 | 2.1.12-stable-1 | vulnerable |
| Ubuntu | libevent | 22.04 | 2.1.12-stable-1build1 | vulnerable |
| Ubuntu | libevent | 22.04 | 2.1.12-stable-1build2 | vulnerable |
| Ubuntu | libevent | 22.04 | 2.1.12-stable-1build3 | vulnerable |
| Ubuntu | libevent | 22.04 | 2.1.12-stable-1ubuntu0.1 | vulnerable |
| Ubuntu | libevent | 22.04 | 2.1.12-stable-1ubuntu0.2 | vulnerable |
| Ubuntu | libevent | 24.04 | 2.1.12-stable-9 | vulnerable |
| Ubuntu | libevent | 24.04 | 2.1.12-stable-9ubuntu2 | vulnerable |
| Ubuntu | libevent | 24.04 | 2.1.12-stable-9ubuntu2.1 | vulnerable |
| Ubuntu | libevent | 24.04 | 2.1.12-stable-9ubuntu2.2 | vulnerable |
| Ubuntu | libevent | 26.04 | 2.1.12-stable-10build1 | vulnerable |
| Ubuntu | libevent | 26.04 | 2.1.12-stable-10build2 | vulnerable |
| Ubuntu | libevent | 26.04 | 2.1.12-stable-10ubuntu0.1 | vulnerable |
| Ubuntu | libevent | 26.04 | 2.1.12-stable-10ubuntu0.2 | fixed |
Fixed-version evidence
| Distribution | Package | Type | Release | Fixed version | Urgency | Origin | Bugs |
|---|---|---|---|---|---|---|---|
| Debian | libevent | source | sid | 2.1.13-stable-1 | not yet assigned | Not reported | Not reported |
| Debian | libevent | source | forky | 2.1.13-stable-1 | not yet assigned | Not reported | Not reported |
| Debian | libevent | source | trixie | 2.1.13-stable-1~deb13u1 | not yet assigned | Not reported | Not reported |
| Debian | libevent | source | bookworm | 2.1.12-stable-8+deb12u1 | not yet assigned | Not reported | Not reported |
| Ubuntu | libevent | deb | noble | 2.1.12-stable-9ubuntu2.2 | Not reported | Not reported | Not reported |
| Ubuntu | libevent-2.1-7t64 | deb | noble | 2.1.12-stable-9ubuntu2.2 | Not reported | Not reported | Not reported |
| Ubuntu | libevent-core-2.1-7t64 | deb | noble | 2.1.12-stable-9ubuntu2.2 | Not reported | Not reported | Not reported |
| Ubuntu | libevent-dev | deb | noble | 2.1.12-stable-9ubuntu2.2 | Not reported | Not reported | Not reported |
| Ubuntu | libevent-extra-2.1-7t64 | deb | noble | 2.1.12-stable-9ubuntu2.2 | Not reported | Not reported | Not reported |
| Ubuntu | libevent-openssl-2.1-7t64 | deb | noble | 2.1.12-stable-9ubuntu2.2 | Not reported | Not reported | Not reported |
| Ubuntu | libevent-pthreads-2.1-7t64 | deb | noble | 2.1.12-stable-9ubuntu2.2 | Not reported | Not reported | Not reported |
| Ubuntu | libevent | deb | pro | 2.1.11-stable-1ubuntu0.1~esm2 | Not reported | USN-8840-1 | Not reported |
| Ubuntu | libevent | deb | 22.04 | 2.1.12-stable-1ubuntu0.2 | Not reported | USN-8840-1 | Not reported |
| Ubuntu | libevent | deb | 24.04 | 2.1.12-stable-9ubuntu2.2 | Not reported | USN-8840-1 | Not reported |
| Ubuntu | libevent | deb | 26.04 | 2.1.12-stable-10ubuntu0.2 | Not reported | USN-8840-1 | Not reported |
| Ubuntu | libevent | deb | 26.04 | 2.1.12-stable-10ubuntu0.2 | Not reported | UBUNTU-CVE-2026-63387 | Not reported |
OpenFactory catalog packages
[Debian 12 (Bookworm)]
- [libevent-2.1-7]Affected
Source package: [libevent]
Details (2)
2.1.12-stable-8· amd64 · bookwormAffected · Fixed:
2.1.12-stable-8+deb12u1nvd · libevent · debian · bookworm; nvd · libevent · debian · 12
2.1.12-stable-8· arm64 · bookwormAffected · Fixed:
2.1.12-stable-8+deb12u1nvd · libevent · debian · bookworm; nvd · libevent · debian · 12
- [libevent-core-2.1-7]Affected
Source package: [libevent]
Details (2)
2.1.12-stable-8· amd64 · bookwormAffected · Fixed:
2.1.12-stable-8+deb12u1nvd · libevent · debian · bookworm; nvd · libevent · debian · 12
2.1.12-stable-8· arm64 · bookwormAffected · Fixed:
2.1.12-stable-8+deb12u1nvd · libevent · debian · bookworm; nvd · libevent · debian · 12
- [libevent-dev]Affected
Source package: [libevent]
Details (2)
2.1.12-stable-8· amd64 · bookwormAffected · Fixed:
2.1.12-stable-8+deb12u1nvd · libevent · debian · bookworm; nvd · libevent · debian · 12
2.1.12-stable-8· arm64 · bookwormAffected · Fixed:
2.1.12-stable-8+deb12u1nvd · libevent · debian · bookworm; nvd · libevent · debian · 12
- [libevent-extra-2.1-7]Affected
Source package: [libevent]
Details (2)
2.1.12-stable-8· amd64 · bookwormAffected · Fixed:
2.1.12-stable-8+deb12u1nvd · libevent · debian · bookworm; nvd · libevent · debian · 12
2.1.12-stable-8· arm64 · bookwormAffected · Fixed:
2.1.12-stable-8+deb12u1nvd · libevent · debian · bookworm; nvd · libevent · debian · 12
- [libevent-openssl-2.1-7]Affected
Source package: [libevent]
Details (2)
2.1.12-stable-8· amd64 · bookwormAffected · Fixed:
2.1.12-stable-8+deb12u1nvd · libevent · debian · bookworm; nvd · libevent · debian · 12
2.1.12-stable-8· arm64 · bookwormAffected · Fixed:
2.1.12-stable-8+deb12u1nvd · libevent · debian · bookworm; nvd · libevent · debian · 12
- [libevent-pthreads-2.1-7]Affected
Source package: [libevent]
Details (2)
2.1.12-stable-8· amd64 · bookwormAffected · Fixed:
2.1.12-stable-8+deb12u1nvd · libevent · debian · bookworm; nvd · libevent · debian · 12
2.1.12-stable-8· arm64 · bookwormAffected · Fixed:
2.1.12-stable-8+deb12u1nvd · libevent · debian · bookworm; nvd · libevent · debian · 12
[Debian 13 (Trixie)]
- [libevent-2.1-7t64]Affected
Source package: [libevent]
Details (3)
2.1.12-stable-10+b1· amd64 · trixieAffected · Fixed:
2.1.13-stable-1~deb13u1nvd · libevent · debian · 13
2.1.12-stable-10+b1· arm64 · trixieAffected · Fixed:
2.1.13-stable-1~deb13u1nvd · libevent · debian · 13
2.1.13-stable-1~deb13u1· amd64 · trixie-securityFixed · Fixed:
2.1.13-stable-1~deb13u1nvd · libevent · debian · 13
- [libevent-core-2.1-7t64]Affected
Source package: [libevent]
Details (3)
2.1.12-stable-10+b1· amd64 · trixieAffected · Fixed:
2.1.13-stable-1~deb13u1nvd · libevent · debian · 13
2.1.12-stable-10+b1· arm64 · trixieAffected · Fixed:
2.1.13-stable-1~deb13u1nvd · libevent · debian · 13
2.1.13-stable-1~deb13u1· amd64 · trixie-securityFixed · Fixed:
2.1.13-stable-1~deb13u1nvd · libevent · debian · 13
- [libevent-dev]Affected
Source package: [libevent]
Details (3)
2.1.12-stable-10+b1· amd64 · trixieAffected · Fixed:
2.1.13-stable-1~deb13u1nvd · libevent · debian · 13
2.1.12-stable-10+b1· arm64 · trixieAffected · Fixed:
2.1.13-stable-1~deb13u1nvd · libevent · debian · 13
2.1.13-stable-1~deb13u1· amd64 · trixie-securityFixed · Fixed:
2.1.13-stable-1~deb13u1nvd · libevent · debian · 13
- [libevent-extra-2.1-7t64]Affected
Source package: [libevent]
Details (3)
2.1.12-stable-10+b1· amd64 · trixieAffected · Fixed:
2.1.13-stable-1~deb13u1nvd · libevent · debian · 13
2.1.12-stable-10+b1· arm64 · trixieAffected · Fixed:
2.1.13-stable-1~deb13u1nvd · libevent · debian · 13
2.1.13-stable-1~deb13u1· amd64 · trixie-securityFixed · Fixed:
2.1.13-stable-1~deb13u1nvd · libevent · debian · 13
- [libevent-openssl-2.1-7t64]Affected
Source package: [libevent]
Details (3)
2.1.12-stable-10+b1· amd64 · trixieAffected · Fixed:
2.1.13-stable-1~deb13u1nvd · libevent · debian · 13
2.1.12-stable-10+b1· arm64 · trixieAffected · Fixed:
2.1.13-stable-1~deb13u1nvd · libevent · debian · 13
2.1.13-stable-1~deb13u1· amd64 · trixie-securityFixed · Fixed:
2.1.13-stable-1~deb13u1nvd · libevent · debian · 13
- [libevent-pthreads-2.1-7t64]Affected
Source package: [libevent]
Details (3)
2.1.12-stable-10+b1· amd64 · trixieAffected · Fixed:
2.1.13-stable-1~deb13u1nvd · libevent · debian · 13
2.1.12-stable-10+b1· arm64 · trixieAffected · Fixed:
2.1.13-stable-1~deb13u1nvd · libevent · debian · 13
2.1.13-stable-1~deb13u1· amd64 · trixie-securityFixed · Fixed:
2.1.13-stable-1~deb13u1nvd · libevent · debian · 13
Observed:
References
- [https://ftp.suse.com/pub/projects/security/csaf/rhsa-2026_67908.json]
- [https://github.com/libevent/libevent/releases/tag/release-2.1.13-stable]
- [https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha]
- [https://github.com/libevent/libevent/security/advisories/GHSA-58rx-7448-jw47]
- [https://nvd.nist.gov/vuln/detail/CVE-2026-63387]
- [https://osv.dev/vulnerability/DEBIAN-CVE-2026-63387]
- [https://osv.dev/vulnerability/UBUNTU-CVE-2026-63387]
- [https://osv.dev/vulnerability/USN-8840-1]
- [https://security-tracker.debian.org/tracker/CVE-2026-63387]
- [https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-63387.json]
- [https://ubuntu.com/security/notices/USN-8840-1]
- [https://wid.cert-bund.de/.well-known/csaf/white/2026/wid-sec-w-2026-3419.json]
[CERT-Bund public advisories] · [Debian Security Tracker] · [FIRST EPSS] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX] · [SUSE security advisories and VEX] · [Ubuntu Security Notices (USN)]