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CVE-2026-42960

⛔ critical
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Summary

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 tha

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.

CVSS Score
10.0
Critical
EPSS Score
0.0
Exploit Probability
Published Date
2026-05-20
First Seen: 2026-05-21
📊 Relative Risk Intelligence

This CVE is Extremely High Risk - more severe than 100.0% of all 328,009 vulnerabilities in our database.

#1
Top 5% most severe
Severity Percentile
🎯 CISA SSVC Assessment Updated: May 20, 2026
🔍 Exploitation Status
None
No known exploits
⚙️ Automatable
NO
Requires human interaction
💥 Technical Impact
Partial
Limited system impact
🏆 Discovered By
TaoFei Guo (Peking University) Yang Luo (Tsinghua University) JianJun Chen (Tsinghua University)
SSVC data provided by CISA
Last Modified 2026-05-20
Source NVD 🔗
CVSS Vector 3.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:H
CVSS Vector 4.0 CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:H/E:P/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:Amber
CWE IDs (Weakness Types)
CWE-349

📦 Affected Products 1

Vendor Product Status Affected Versions
nlnetlabs unbound Affected
< 1.25.1

🔗 References 1

https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-...
Mitigation Vendor Advisory

🔗 Related CVEs 6

CVE ID Severity CVSS EPSS Summary Published
CVE-2026-32792 🔶 medium 5.3 0.1 NLnet Labs Unbound 1.6.2 up to and including version 1.25.0 has a denial of service vulnerability when compiled with DNS... 2026-05-20
CVE-2026-33278 ⛔ critical 9.8 0.3 NLnet Labs Unbound 1.19.1 up to and including version 1.25.0 has a vulnerability in the DNSSEC validator that enables de... 2026-05-20
CVE-2026-40622 ⚠️ high 7.5 0.0 NLnet Labs Unbound 1.16.2 up to and including version 1.25.0 has a vulnerability of the 'ghost domain names' family of a... 2026-05-20
CVE-2026-41292 ⚠️ high 7.5 0.1 NLnet Labs Unbound up to and including version 1.25.0 is vulnerable to a degradation of service attack related to parsin... 2026-05-20
CVE-2026-42534 🔶 medium 5.3 0.1 NLnet Labs Unbound up to and including version 1.25.0 has a vulnerability in the jostle logic that could defeat its purp... 2026-05-20
CVE-2026-42923 🔶 medium 5.3 0.1 NLnet Labs Unbound up to and including version 1.25.0 has a vulnerability in the DNSSEC validator where the code path to... 2026-05-20
These CVEs affect the same products