CVE-2026-42959

EPSS 0.78%
Veröffentlicht 20.05.2026 09:20:45
Zuletzt bearbeitet 30.06.2026 03:19:42
Quelle sep@nlnetlabs.nl
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Crash during DNSSEC validation of malicious content

NLnet Labs Unbound up to and including version 1.25.0 has a denial of service vulnerability in the DNSSEC validator that can lead to a crash given malicious upstream replies. When Unbound constructs chase-reply messages for validation, the code uses the wrong counter to calculate write offsets for ADDITIONAL section rrsets. DNAME duplication could increase the ANSWER section count and authority filtering could decrease the AUTHORITY section count and create an uninitialized array slot. Combining these two, the validator later dereferences this uninitialized pointer, causing an immediate process crash. An adversary controlling a DNSSEC-signed domain can trigger this bug with a single query by configuring a DNAME chain with unsigned CNAMEs and a response containing unsigned AUTHORITY records alongside signed ADDITIONAL glue records. Unbound 1.25.1 contains a patch with a fix to use the proper counters to calculate the write offsets.

Betroffene Produkte Warnungen 0 Metriken 4 CWE 1 Referenzen 11

NVD 1 VulnDex Vulnerability Enrichment 1

Daten sind bereitgestellt durch National Vulnerability Database (NVD)

Nlnetlabs ≫ Unbound Version < 1.25.1

VulnDex Vulnerability Enrichment

Diese Information steht angemeldeten Benutzern zur Verfügung.

Zu dieser CVE wurde keine Warnung gefunden.

EPSS Metriken
Typ	Quelle	Score	Percentile
EPSS	FIRST.org	0.78%	0.513

CVSS Metriken
Quelle	Base Score	Exploit Score	Impact Score	Vector String
nvd@nist.gov	7.5	3.9	3.6	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
sep@nlnetlabs.nl	8.7	0	0	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:X/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	7.5	3.9	3.6	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H