CVE-2026-40622
📛 CVE Title
Another 'ghost domain names' attack variant
Description
NLnet Labs Unbound 1.16.2 up to and including version 1.25.0 has a vulnerability of the 'ghost domain names' family of attacks that could extend the ghost domain window by up to one cached TTL configured value. Similar to other 'ghost domain names' attacks, an adversary needs to control a (ghost) zone and be able to query a vulnerable Unbound. A single client NS query can cause Unbound to overwrite the cached expired parent-side referral NS rrset with the child-side apex NS rrset and essentially extend the ghost domain window by up to one cached TTL configured value ('cache-max-ttl'). In configurations where 'harden-referral-path: yes' is used (non-default configuration), no client NS query is required since Unbound implicitly performs that query. Unbound 1.25.1 contains a patch with a fix that does not allow extension of TTLs for (parent) NS records regardless of their trust.
Overview
- State
- PUBLISHED
- Assigner (CNA)
- NLnet Labs
- CVSS severity
- MEDIUM
- CVSS score
- 6.6 / 10
- CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Amber- Effective score
- 6.6 / 10 MEDIUM source: CNA overview
- CWE(s)
-
CWE-346 - Reserved
- 2026-05-07
- Published
- 2026-05-20 09:18 UTC
- Last updated
- 2026-05-20 12:12 UTC
- Source
- https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/40xxx/CVE-2026-40622.json
- Linked Threat
- CVE-2026-40622 — CVE-2026-40622
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 10:16:26 UTC
- NVD last modified
- 2026-05-20 14:02:12 UTC
- EPSS score
- 0.0002 (probability of exploitation in next 30 days)
- EPSS percentile
- 5.46% vs all CVEs — higher = more likely to be exploited, as of 2026-05-24
NVD / KEV / EPSS data refreshed 2026-05-25 00:42 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-2026-31080 - Assigner
- NLnet Labs
- Published
- May 20, 2026, 9:18:41 AM
- Updated
- May 20, 2026, 12:12:33 PM
- EUVD base score (CVSS 4.0)
-
6.6 / 10
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Amber - EUVD-reported EPSS
- 0.0200
- Vendors
- NLnet Labs
- Products
-
Unbound (1.16.2 <1.25.1)
- Aliases
-
GHSA-m3vq-fgh9-hq65
ENISA description: NLnet Labs Unbound 1.16.2 up to and including version 1.25.0 has a vulnerability of the 'ghost domain names' family of attacks that could extend the ghost domain window by up to one cached TTL configured value. Similar to other 'ghost domain names' attacks, an adversary needs to control a (ghost) zone and be able to query a vulnerable Unbound. A single client NS query can cause Unbound to overwrite the cached expired parent-side referral NS rrset with the child-side apex NS rrset and essentially extend the ghost domain window by up to one cached TTL configured value ('cache-max-ttl'). In configurations where 'harden-referral-path: yes' is used (non-default configuration), no client NS query is required since Unbound implicitly performs that query. Unbound 1.25.1 contains a patch with a fix that does not allow extension of TTLs for (parent) NS records regardless of their trust.
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 2026-08-15 03:01 UTC (source: CVRF).
- MS severity
- Moderate
- 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 |
1.16.2 (affected)
|
— |
Vendor references (1)
References embedded in the original CVE record by the assigning CNA.
- https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-40622.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-2026-40622 msrc
- https://nvd.nist.gov/vuln/detail/CVE-2026-40622 tenable:nvd.nist.gov
- https://www.cve.org/CVERecord?id=CVE-2026-40622 tenable:www.cve.org
- https://www.first.org/epss/ tenable:www.first.org
- https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-40622.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-2026-40622.txt sep@nlnetlabs.nl
Remediations (16)
Remediations are stored against the linked Threat row; the list below is deduplicated across both pages.
-
web:betanews.com
Another month, another update for Windows which is problematic. This time around, it is the May 2026 Windows 11 security update - or the KB5089549 update.
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:krebsonsecurity.com
Microsoft expects that exploitation is more likely. May's Patch Tuesday is a welcome respite from April, which saw Microsoft fix a near-record 167 security flaws.
2026-05-23 22:16 UTC -
web:portal.msrc.microsoft.com
The Security Update Guide provides information on the latest Microsoft security updates, helping users understand and address potential vulnerabilities effectively.
2026-05-23 22:16 UTC -
web:www.cisecurity.org
<p>Multiple vulnerabilities have been discovered in Microsoft products, the most severe of which could allow for remote code execution. Successful exploitation of the most severe of these vulnerabilities could result in an attacker gaining the same privileges as the logged-on user. Depending on the privileges associated with the user, an attacker could then install programs; view, change, or ...
2026-05-23 22:16 UTC -
web:www.maketecheasier.com
Check out the latest Windows 11 and Windows 10 update problems and their solutions, as recommended by Microsoft experts.
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.pcworld.com
Windows 11's Secure Boot fix update finally rolls out to more PCs Important security certificates for Windows 11 will soon expire for many users.
2026-05-23 22:16 UTC -
web:www.windowslatest.com
Windows 11 April 2026 update adds Narrator Copilot support, faster Settings, File Explorer fixes, and key security improvements.
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:blog.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:blog.talosintelligence.com
Microsoft has released its monthly security update for April 2026 , which includes 165 vulnerabilities affecting a wide range of products, including eight Microsoft marked as "critical." CVE - 2026 -23666 is a critical Denial of Service (DoS) vulnerability that affects the .NET framework. Successful exploitation could allow the attacker to deny service over the network. CVE - 2026 -32157 is a ...
2026-05-26 02:59 UTC -
web:blogs.oracle.com
For more information about the Critical Patch Update program, see the security vulnerability remediation practices page located on the Oracle Trust Center.
2026-05-26 02:59 UTC -
web:cyberpress.org
The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has added two actively exploited Microsoft Defender vulnerabilities to its Known Exploited Vulnerabilities (KEV) catalog, issuing an urgent remediation directive for federal agencies with a due date of June 3, 2026 .
2026-05-26 02:59 UTC -
web:msrc.microsoft.com
Security Update Guide - Microsoft Security Response Center
2026-05-26 02:59 UTC -
web:www.crowdstrike.com
Microsoft's April 2026 Patch Tuesday addresses 164 CVEs , featuring 8 Critical vulnerabilities, one exploited zero-day, and one disclosed zero-day.
2026-05-26 02:59 UTC
AI Forensic Analysis
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Raw JSON
The full cvelistV5 record. Download as CVE-2026-40622.json.
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