| Name | CVE-2026-4437 |
| Description | Calling gethostbyaddr or gethostbyaddr_r with a configured nsswitch.conf that specifies the library's DNS backend in the GNU C Library version 2.34 to version 2.43 could, with a crafted response from the configured DNS server, result in a violation of the DNS specification that causes the application to treat a non-answer section of the DNS response as a valid answer. |
| Source | CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
| Debian Bugs | 1131435 |
Vulnerable and fixed packages
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|
| glibc (PTS) | bullseye | 2.31-13+deb11u11 | vulnerable |
| bullseye (security) | 2.31-13+deb11u13 | vulnerable |
| bookworm | 2.36-9+deb12u13 | vulnerable |
| bookworm (security) | 2.36-9+deb12u7 | vulnerable |
| trixie | 2.41-12+deb13u2 | vulnerable |
| forky, sid | 2.42-14 | fixed |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|
| glibc | source | (unstable) | 2.42-14 | | | 1131435 |
Notes
[trixie] - glibc <no-dsa> (Minor issue)
[bookworm] - glibc <no-dsa> (Minor issue)
[bullseye] - glibc <postponed> (Minor issue, validation issue)
https://sourceware.org/bugzilla/show_bug.cgi?id=34014
Proposed patch: https://inbox.sourceware.org/libc-alpha/20260320194250.1089143-1-carlos@redhat.com/
https://www.openwall.com/lists/oss-security/2026/03/23/2