Bug 2458518 (CVE-2026-4892) - CVE-2026-4892 dnsmasq: DHCPv6 CLID buffer overflow in helper process
Summary: CVE-2026-4892 dnsmasq: DHCPv6 CLID buffer overflow in helper process
Keywords:
Status: NEW
Alias: CVE-2026-4892
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 22:50 UTC by OSIDB Bzimport
Modified: 2026-05-26 04:57 UTC (History)
3 users (show)

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

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2026:19158 0 None None None 2026-05-19 16:10:34 UTC
Red Hat Product Errata RHSA-2026:19373 0 None None None 2026-05-19 21:41:10 UTC
Red Hat Product Errata RHSA-2026:20589 0 None None None 2026-05-26 04:57:26 UTC

Description OSIDB Bzimport 2026-04-14 22:50:33 UTC 
In helper.c:265, the DHCPv6 CLID is hex-encoded via sprintf("%.2x") into daemon->packet (5,131 bytes) with no length cap on the CLID. DHCPv6 CLIDs can be up to 65,535 bytes (131,070 hex characters). The helper process retains root privileges. log6_packet() already caps CLID to 100 bytes for logging, but the helper code path was missed. Fix: add && i < 100 bound to the encoding loop, matching the logging cap.
Comment 2 errata-xmlrpc 2026-05-19 16:10:33 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
Comment 3 errata-xmlrpc 2026-05-19 21:41:09 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:19373 https://access.redhat.com/errata/RHSA-2026:19373
Comment 4 errata-xmlrpc 2026-05-26 04:57:25 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2026:20589 https://access.redhat.com/errata/RHSA-2026:20589
Note You need to log in before you can comment on or make changes to this bug.