SB2026060462 - Red Hat Enterprise Linux 10 update for unbound

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Main Vulnerability Database SB2026060462

SB2026060462 - Red Hat Enterprise Linux 10 update for unbound

Published: June 4, 2026

Security Bulletin ID SB2026060462
CSH Severity
Medium
Patch available
YES
Number of vulnerabilities 3
Exploitation vector Remote access
Highest impact Denial of service

Breakdown by Severity

Medium 100%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 3 vulnerabilities.


1) Heap-based buffer overflow (CVE-ID: CVE-2026-42944)

CWE-ID: CWE-122 - Heap-based Buffer Overflow

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green


The vulnerability allows a remote attacker to cause a denial of service.

The vulnerability exists due to a heap-based buffer overflow in the EDNS option encoder when processing queries containing multiple NSID and/or DNS Cookie EDNS and/or EDNS Padding options. A remote attacker can send a specially crafted query to cause a denial of service.

Only instances with the relevant EDNS options enabled are vulnerable.


2) Access of Uninitialized Pointer (CVE-ID: CVE-2026-42959)

CWE-ID: CWE-824 - Access of Uninitialized Pointer

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green


The vulnerability allows a remote attacker to cause a denial of service.

The vulnerability exists due to use of an uninitialized pointer in the DNSSEC validator when constructing chase-reply messages for validation. A remote attacker can provide a malicious upstream reply to cause a denial of service.

Exploitation requires control of a DNSSEC-signed domain and can be triggered with a single query using a DNAME chain with unsigned CNAMEs and a response containing unsigned AUTHORITY records alongside signed ADDITIONAL glue records.


3) Use-after-free (CVE-ID: CVE-2026-33278)

CWE-ID: CWE-416 - Use After Free

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green


The vulnerability allows a remote attacker to cause a denial of service and potentially execute arbitrary code.

The vulnerability exists due to use-after-free in Unbound DNSSEC validator when processing validation state for DS sub-queries after deep-copying response messages during NSEC3 computational budget exhaustion. A remote attacker can control a malicious signed zone and query a vulnerable resolver to cause a denial of service and potentially execute arbitrary code.

Exploitation requires control of a malicious signed zone.


Remediation

Install update from vendor's website.

References