CVE-2026-81642
Exploitation: none CVSS 9.1 CRITICALCVSS base score: 9.1 (Critical) vendor CNA · v4.0
Score assigned by the vendor's own CVE Numbering Authority (CNA); CISA's Vulnrichment program adds a score only when the CNA omits one. Vulnrichment source record → (opens in a new tab)
Vendor: NLnet Labs Product: Unbound
Description
In NLnet Labs Unbound up to and including 1.26.0, a vulnerability was found in the DNSSEC validator that enables denial of service and possible remote code execution as a result of digesting DNSKEYs. A DNSKEY with an owner compression pointer to its own RDATA can overflow the digest buffer. Remote code execution is possible through attacker controlled data. An adversary can exploit the vulnerability by controlling a malicious zone and querying a vulnerable Unbound.
Research & News Coverage
| Date | Source | Article |
|---|---|---|
| 2026-09-17 | The Hacker News | Critical Unbound DNSSEC Validator Flaw Could Allow RCE via a Malicious DNS Zone (opens in a new tab) |
Articles from monitored vendor research blogs and security news feeds that specifically mention this CVE. Coverage begins when feed monitoring started; earlier articles are not indexed.
Lifecycle Timeline
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2026-09-16
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2026-09-18Public exploit code 2 days laterPublic GitHub repository suominen/CVE-2026-81642 — unvetted, may contain malware
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not recordedEPSS flags exploitation riskTracked, and has never reached 10% (peak 1.0%).
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not recordedFirst national advisoryNo tracked government advisory analyses this CVE. Routine KEV catalog-addition alerts do not count here.
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not recordedAdded to CISA KEVNot in the CISA KEV catalog.
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not recordedFederal remediation dueNo remediation deadline set.
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not recordedVendor fix publishedNo dated vendor fix. Only Microsoft publishes a machine-readable release date; other vendors state a fixed version without one.
Each milestone comes from a different source, so gaps between them are gaps in what those sources publish, not evidence that nothing happened. EPSS history for this CVE holds 54 points from 2026-09-18, tracked daily from 2026-09-18; earlier points are weekly, which dates a spike to within a week. Peak probability 1.0% on 2026-09-26.
Published Applicability
Check whether a specific version is affected →
What each source publishes about which product versions carry this vulnerability, kept as written rather than merged. Absence here means no source has published applicability data, not that nothing is affected.
Detection & Exploitation
Coverage across public collections only: Nuclei and OpenVAS NVT (scan);
Snort and Suricata ET Open (network); Sigma and YARA (host/SIEM);
Metasploit, Exploit-DB, public GitHub repositories and NVD exploit references (exploit). Absence
here means nothing public was found, not that detection is impossible.
GitHub PoC repositories are collected automatically by
PoC-in-GitHub (opens in a new tab) (CC0) and filtered to repositories that are
still online, contain code, and are starred or at least two weeks old. They are
still not vetted: some are fakes and some are malware. Treat
them as evidence that code was published, not as code to run.
NVD exploit references are links NVD's analysts tag as exploits; they confirm
an exploit was referenced but carry no date. This product uses data from the
NVD but is not endorsed or certified by the NVD.
OpenVAS coverage derives from the Greenbone Community Feed, made available
under the Open Database License (ODbL) v1.0 (opens in a new tab);
its individual Vulnerability Tests are licensed
GNU GPL v2 (opens in a new tab).
| First seen | Tool | Evidence | Earliest reference |
|---|---|---|---|
| 2026-09-18 | GitHub PoC | Unvetted — public repository | suominen/CVE-2026-81642 (opens in a new tab) |
Metasploit is dated by the first commit of the module file, Exploit-DB by its publication date, and GitHub repositories by their creation date. GitHub PoC repositories are filtered (still online, contain code, starred or at least two weeks old) but not vetted: some are fakes and some are malware, so they show that code was published, not that it works or is safe to run. Evidence tiers are explained on the About page.
Distribution Status
Where the distribution has shipped a fix, and in which version. Green means the release has resolved it, amber that it is still open. Data from the Debian Security Tracker (opens in a new tab), used under Debian's MIT / GPLv2+ terms. Debian is upstream of several other distributions, so a fix here often precedes theirs.
Fix & Cross-References
Patch and commit links and ecosystem advisory ids as published by OSV.dev (opens in a new tab). Links are listed as published, not vetted.
CISA Assessment (Vulnrichment / SSVC)
Federal Remediation Window (BOD 26-04)
| If the asset is | Remediate within | Table 1 row |
|---|---|---|
| Publicly exposed | 3 days | 5 of 16 |
| Not publicly exposed | 60 days | 13 of 16 |
BOD 26-04 (opens in a new tab) replaced the single KEV deadline of BOD 22-01 with four inputs: whether the asset is publicly exposed, KEV status, whether exploitation is automatable, and technical impact. Exposure belongs to each agency's asset, not to the CVE, so both outcomes are shown. Automatable and technical impact come from the CISA assessment above. Days are calendar days; for KEV entries the clock starts on the date it was added, and otherwise when the agency identifies the vulnerability on an asset. Agencies make the final exposure call asset by asset, and may set shorter timelines.
D3FEND Countermeasures
Defensive techniques inferred by MITRE D3FEND (opens in a new tab) from the underlying weakness (CWE-122) — general hardening and detection guidance for this weakness class, not a vendor patch for this specific CVE.