Bug 34069 (CVE-2026-6238) - Buffer overread in ns_sprintrrf with corrupted RDATA field (CVE-2026-6238)
Summary: Buffer overread in ns_sprintrrf with corrupted RDATA field (CVE-2026-6238)
Status: ASSIGNED
Alias: CVE-2026-6238
Product: glibc
Classification: Unclassified
Component: network (show other bugs)
Version: 2.44
: P2 normal
Target Milestone: ---
Assignee: Florian Weimer
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2026-04-11 20:50 UTC by Florian Weimer
Modified: 2026-04-30 11:01 UTC (History)
2 users (show)

See Also:
Host:
Target:
Build:
Last reconfirmed:
Project(s) to access:
ssh public key:
fweimer: security+

Attachments
Add an attachment (proposed patch, testcase, etc.)

Note You need to log in before you can comment on or make changes to this bug.
Description Florian Weimer 2026-04-11 20:50:31 UTC 
The RDATA length is not validated while parsing LOC, CERT, TKEY, TSIG, and A6 records. Applications using the deprecated ns_sprintrrf, ns_sprintrr, fp_nquery may encounter crashes or read uninitialized memory when processing corrupted DNS packets where the RDATA contents is not structured correctly.

Found while writing a test case for bug 34033.
Comment 1 Florian Weimer 2026-04-30 11:01:26 UTC 
Patches posted:

[PATCH 0/5] Fixes for CVE-2026-5435, CVE-2026-6238
<https://inbox.sourceware.org/libc-alpha/cover.1777546194.git.fweimer@redhat.com/>