CVE-2026-42960
📛 CVE Title
Possible cache poisoning via promiscuous records for the authority section
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.
Overview
- State
- PUBLISHED
- Assigner (CNA)
- NLnet Labs
- CVSS severity
- MEDIUM
- CVSS score
- 5.7 / 10
- CVSS vector
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/U:Amber- Effective score
- 5.7 / 10 MEDIUM source: CNA overview
- MSRC score
- 10.0 / 10 CRITICAL MS rating: Moderate
- CWE(s)
-
CWE-349 - Reserved
- 2026-05-07
- Published
- 2026-05-20 09:21 UTC
- Last updated
- 2026-05-20 13:04 UTC
- Source
- https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/42xxx/CVE-2026-42960.json
- Linked Threat
- CVE-2026-42960 — CVE-2026-42960
NVD triage scoring NVD CVE 2.0
Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.
- NVD published
- 2026-05-20 10:16:28 UTC
- NVD last modified
- 2026-05-20 22:51:43 UTC
- NVD CVSS v3.1
- 10.0 / 10 CRITICAL source: nvd@nist.gov
- NVD CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:H- Exploitability subscore
- 3.9 / 10
- Impact subscore
- 5.8 / 10
- EPSS score
- 0.0002 (probability of exploitation in next 30 days)
- EPSS percentile
- 6.72% vs all CVEs — higher = more likely to be exploited, as of 2026-05-24
NVD / KEV / EPSS data refreshed 2026-05-25 00:39 UTC. Re-run the 🛰 Backfill from NVD button above to refresh.
European Union Vulnerability Database ENISA EUVD
ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.
- EUVD ID
-
EUVD-2026-31083 - Assigner
- NLnet Labs
- Published
- May 20, 2026, 9:21:02 AM
- Updated
- May 20, 2026, 1:04:34 PM
- EUVD base score (CVSS 4.0)
-
5.7 / 10
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/U:Amber - EUVD-reported EPSS
- 0.0300
- Vendors
- NLnet Labs
- Products
-
Unbound (0 <1.25.1)
- Aliases
-
GHSA-x7f7-rggg-4jvv
ENISA 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.
EUVD references (1)
Microsoft Security Response Center MSRC
Microsoft's vendor-authoritative record from the Security Update Guide — its own CVSS score, impact, severity rating, exploit assessment, and KB-article fixes. Refreshed 2026-11-03 04:06 UTC (source: CVRF).
- MS severity
- Moderate
- MS CVSS base score
- 10.0 / 10 (temporal 10.0)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:H - Release
- 2026-May
Microsoft remediations / KB articles (2)
- CBL-Mariner Releases — Vendor Fix / Security Update (fixed build 1.25.1-1)
- https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade — None Available / CBL-Mariner Releases
Affected products (1)
| Vendor | Product | Versions | Platforms |
|---|---|---|---|
| NLnet Labs | Unbound |
0 (affected)
|
— |
Affected products — CPE 2.3 (1) NVD
NVD's normalized CPE 2.3 matchers, used by vendor tools (vulnerability scanners, asset managers) for automated detection. Compare with the CNA's free-text "Affected products" section above.
cpe:2.3:a:nlnetlabs:unbound:*:*:*:*:*:*:*:*
Vendor references (1)
References embedded in the original CVE record by the assigning CNA.
- https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-42960.txt vendor-advisory
Web references (6)
DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.
- None Available msrc
- MSRC update guide: CVE-2026-42960 msrc
- https://nvd.nist.gov/vuln/detail/CVE-2026-42960 tenable:nvd.nist.gov
- https://www.cve.org/CVERecord?id=CVE-2026-42960 tenable:www.cve.org
- https://www.first.org/epss/ tenable:www.first.org
- https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-42960.txt tenable:www.nlnetlabs.nl
NVD-tagged references (1)
Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.
- https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-42960.txt sep@nlnetlabs.nl MitigationVendor Advisory
Remediations (15)
Remediations are stored against the linked Threat row; the list below is deduplicated across both pages.
-
web:app.opencve.io
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.
2026-05-23 22:16 UTC -
web:cybersecuritynews.com
Microsoft's May 2026 Patch Tuesday lands with a heavy enterprise focus, fixing 120 vulnerabilities across Windows, Office, Azure, developer tools, and Microsoft 365 apps, including 29 remote code execution (RCE) flaws rated Critical.
2026-05-23 22:16 UTC -
web:msrc.microsoft.com
Security Update Guide - Microsoft Security Response Center
2026-05-23 22:16 UTC -
web:nvd.nist.gov
An official website of the United States government Here's how you know
2026-05-23 22:16 UTC -
web:ubuntu.com
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.
2026-05-23 22:16 UTC -
web:www.bleepingcomputer.com
Today is Microsoft's May 2026 Patch Tuesday, with security updates for 120 flaws and no zero-days disclosed this month.
2026-05-23 22:16 UTC -
web:www.msn.com
Original story: Microsoft has released an emergency patch for a vulnerability in the company's Office programs that's already being exploited by hackers.
2026-05-23 22:16 UTC -
web:www.oracle.com
This Critical Patch Update contains 481 new security patches across the product families listed below. Please note that an MOS note summarizing the content of this Critical Patch Update and other Oracle Software Security Assurance activities is located at April 2026 Critical Patch Update: Executive Summary and Analysis.
2026-05-23 22:16 UTC -
web:www.sherlockforensics.com
nlnetlabs unbound vulnerability ( CVE-2026-42960 ) scores CVSS 10.0 CRITICAL. Analysis of affected systems and remediation steps.
2026-05-23 22:16 UTC -
web:zecurit.com
Get the complete breakdown of Microsoft's May 2026 Patch Tuesday. We analyze the latest security updates and all critical CVEs .
2026-05-23 22:16 UTC -
web:cyberscoop.com
Threats Microsoft addresses 137 vulnerabilities in May's Patch Tuesday, including 13 rated critical The high volume of vulnerabilities reflects a growing trend researchers have been anticipating as artificial intelligence models are deployed to find previously uncovered defects in code.
2026-05-26 02:59 UTC -
web:threatprotect.qualys.com
With Qualys Policy Audit's out-of-the-box mitigation or Compensatory Controls, which reduce the risk of a vulnerability being exploited because the remediation ( fix / patch ) cannot be done immediately, these security controls are not recommended by any industry standards, such as CIS and DISA-STIG.
2026-05-26 02:59 UTC -
web:www.crowdstrike.com
Microsoft has released security updates for 130 vulnerabilities, including 30 critical, in its May 2026 Patch Tuesday rollout.
2026-05-26 02:59 UTC -
web:www.endorlabs.com
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.
2026-05-26 02:59 UTC -
web:www.tenable.com
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.
2026-05-26 02:59 UTC
AI Forensic Analysis
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Raw JSON
The full cvelistV5 record. Download as CVE-2026-42960.json.
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