CVE-2026-42960 Possible cache poisoning via promiscuous records for the authority section
Attackers can poison the DNS cache by injecting malicious authority records, potentially redirecting users to malicious sites.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-42960?
CVE-2026-42960 is a medium-severity vulnerability in Nlnetlabs Unbound, published on 20 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
NLnet Labs Unbound up to and including version 1.25.0 is vulnerable to poisoning via promiscuous records for the authority section. Promiscuous RRSets that complement DNS replies in the authority section can be used to trick Unbound to cache such records. If an adversary is able to attach such records in a reply (i.e., spoofed packet, fragmentation attack) he would be able to poison Unbound's cache. A malicious actor can exploit the possible poisonous effect by injecting RRSets other than NS that are also accompanied by address records in a reply, for example MX. This could be achieved by trying to spoof a reply packet or fragmentation attacks. Unbound would then accept the relative address records in the additional section and cache them if the authority RRSet has enough trust at this point, i.e., in-zone data for the delegation point. Unbound 1.25.1 contains a patch with a fix that disregards address records from the additional section if they are not explicitly relevant only to authority NS records, mitigating the possible poison effect. This is a complement fix to CVE-2025-11411.
Weakness: CWE-349
Which versions are affected by CVE-2026-42960?
It affects 1 product.
Products include Nlnetlabs Unbound.
How do I fix CVE-2026-42960?
Apply the vendor's patch.
Is CVE-2026-42960 being exploited?
There is no known exploitation of CVE-2026-42960 in the wild and no public exploit code.
Other vulnerabilities in Nlnetlabs Unbound
- CVE-2026-81642 Heap buffer overflow and possible Remote Code Execution when digesting DNSKEY
- CVE-2026-33278 Possible arbitrary code execution during DNSSEC validation
- CVE-2026-42944 Heap overflow with multiple NSID, COOKIE, PADDING EDNS options
- CVE-2026-42959 Crash during DNSSEC validation of malicious content
- CVE-2026-82717 CNAME synthesis could lead to heap corruption
Sources
Also known as ALPINE-CVE-2026-42960, AZL-87018, CLSA-2026-1779960466, CLSA-2026-1779961008, DEBIAN-CVE-2026-42960, ECHO-6546-2c8e-af78 and 4 more.