9.8

CVE-2026-33278

Possible arbitrary code execution during DNSSEC validation

NLnet Labs Unbound 1.19.1 up to and including version 1.25.0 has a vulnerability in the DNSSEC validator that enables denial of service and possible remote code execution as a result of deep copying a data structure and erroneously overwriting a destination pointer. An adversary can exploit the vulnerability by controlling a malicious signed zone and querying a vulnerable Unbound. When DS sub-queries need to suspend validation due to NSEC3 computational budget exhaustion (introduced in Unbound 1.19.1), Unbound deep-copies response messages to preserve them across memory region teardown. A struct-assignment bug overwrites the destination's pointer with the source's pointer. After the sub-query region is freed, the resumed validator dereferences this dangling pointer, triggering a crash or potentially enabling arbitrary code execution. Unbound 1.25.1 contains a patch with a fix to preserve the correct pointer when deep copying the data structure.
Daten sind bereitgestellt durch National Vulnerability Database (NVD)
Nlnetlabs ≫ Unbound Version >= 1.19.1 < 1.25.1
VulnDex Vulnerability Enrichment
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Zu dieser CVE wurde keine Warnung gefunden.
EPSS Metriken
Typ Quelle Score Percentile
EPSS FIRST.org 1.27% 0.662
CVSS Metriken
Quelle Base Score Exploit Score Impact Score Vector String
nvd@nist.gov 9.8 3.9 5.9
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
sep@nlnetlabs.nl 9.1 0 0
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Red
0b0ca135-0b70-47e7-9f44-1890c2a1c46c 8.1 2.2 5.9
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
CWE-416 Use After Free

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.

CWE-672 Operation on a Resource after Expiration or Release

The product uses, accesses, or otherwise operates on a resource after that resource has been expired, released, or revoked.

https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-33278.txt
Vendor Advisory
Mitigation
https://access.redhat.com/errata/RHSA-2026:19752
https://access.redhat.com/errata/RHSA-2026:23231
https://access.redhat.com/errata/RHSA-2026:24369
https://access.redhat.com/security/cve/CVE-2026-33278
https://bugzilla.redhat.com/show_bug.cgi?id=2479808
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33278.json