Bug 2458521 (CVE-2026-5172) - CVE-2026-5172 dnsmasq: extract_addresses() OOB read via malformed rdlen
Summary: CVE-2026-5172 dnsmasq: extract_addresses() OOB read via malformed rdlen
Keywords:
Status: NEW
Alias: CVE-2026-5172
Deadline: 2026-05-09
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
high
high
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-04-14 22:59 UTC by OSIDB Bzimport
Modified: 2026-05-19 16:10 UTC (History)
3 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
Embargoed:

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System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2026:19158 0 None None None 2026-05-19 16:10:37 UTC

Description OSIDB Bzimport 2026-04-14 22:59:51 UTC 
In extract_addresses() at rfc1035.c:943, the rdlen field of an RR is trusted without verification. When extract_name() is called on the record's data, it can advance p1 past the calculated end of the record (endrr). The subsequent calculation of remaining bytes (endrr - p1) underflows to a huge unsigned value, causing a massive heap OOB read and certain crash. Fix: add p1 > endrr check after the extract_name() call.
Comment 2 errata-xmlrpc 2026-05-19 16:10:36 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:19158 https://access.redhat.com/errata/RHSA-2026:19158
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