Bug 2458516 (CVE-2026-4890) - CVE-2026-4890 dnsmasq: NSEC bitmap parsing infinite loop
Summary: CVE-2026-4890 dnsmasq: NSEC bitmap parsing infinite loop
Keywords:
Status: NEW
Alias: CVE-2026-4890
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 22:39 UTC by OSIDB Bzimport
Modified: 2026-07-01 21:09 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 16:10:32 UTC
Red Hat Product Errata RHSA-2026:19373 0 None None None 2026-05-19 21:41:09 UTC
Red Hat Product Errata RHSA-2026:20589 0 None None None 2026-05-26 04:57:24 UTC
Red Hat Product Errata RHSA-2026:34508 0 None None None 2026-07-01 21:09:40 UTC

Description OSIDB Bzimport 2026-04-14 22:39:35 UTC 
NSEC/NSEC3 bitmap window iteration in dnssec.c advances by p[1] instead of p[1] + 2, missing the 2-byte window header. When bitmap_length=0, neither rdlen nor p change, creating an infinite loop. Two instances at dnssec.c:1290 and dnssec.c:1450. Reachable before RRSIG validation so no valid signatures are needed. One of the two sites was coincidentally fixed in 2.92. Fix: add +2 to both the pointer advance and rdlen decrement.
Comment 2 errata-xmlrpc 2026-05-19 16:10:31 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 21:41:08 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 04:57:23 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
Comment 5 errata-xmlrpc 2026-07-01 21:09:39 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.6 Extended Update Support

Via RHSA-2026:34508 https://access.redhat.com/errata/RHSA-2026:34508
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