CVE-2026-81634

HIGHPre-NVD 7.57.5—
EchelonGraph scoreHIGH confidence

Score 7.5 from GitHub Security Advisory (severity: HIGH) published 2026-09-16. a secondary CVSS source baseline 7.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 5 sources updated this week
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.5Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

In NLnet Labs Unbound up to and including 1.26.0, a 255 length query name with a large TCP response can lead to a heap buffer overflow during the RRSet canonicalisation routine. This is caused by missing to add the first owner name into the buffer length check. A malicious actor operating a malicious name server or tampering with an incoming response to Unbound (canonicalisation happens before DNSSEC validation), can trigger the vulnerability.

CVSS v3
7.5
EG Score
7.5(high)
EG Risk
49(Track)
EG Risk 49/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity75% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
29%
KEV
Not listed

Published

September 16, 2026

Last Modified

September 16, 2026

Advisory Details (1)

Auto-updated Sep 16, 2026
No patch confirmed yet.
generic
https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-81634.txt

Vendor Advisories for CVE-2026-81634(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 34× in last 7d / 34× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-09-21 06:36 UTCEG score recompute
  2. 2026-09-21 06:36 UTCVendor advisory
  3. 2026-09-21 06:36 UTCGHSA enrichment
  4. 2026-09-20 20:16 UTCEPSS rescore
  5. 2026-09-20 18:45 UTCVendor advisory
  6. 2026-09-20 18:45 UTCGHSA enrichment
  7. 2026-09-20 06:55 UTCVendor advisory
  8. 2026-09-20 06:54 UTCGHSA enrichment
  9. 2026-09-19 18:52 UTCEG score recompute
  10. 2026-09-19 18:52 UTCVendor advisory
  11. 2026-09-19 18:52 UTCGHSA enrichment
  12. 2026-09-19 07:01 UTCEG score recompute
  13. 2026-09-19 07:01 UTCVendor advisory
  14. 2026-09-19 07:01 UTCGHSA enrichment
  15. 2026-09-18 19:28 UTCEPSS rescore
  16. 2026-09-18 19:11 UTCVendor advisory
  17. 2026-09-18 19:11 UTCGHSA enrichment
  18. 2026-09-18 07:20 UTCEG score recompute
  19. 2026-09-18 07:20 UTCVendor advisory
  20. 2026-09-18 07:20 UTCGHSA enrichment
  21. 2026-09-17 19:29 UTCVendor advisory
  22. 2026-09-17 19:29 UTCGHSA enrichment
  23. 2026-09-17 07:36 UTCVendor advisory
  24. 2026-09-17 07:36 UTCGHSA enrichment
  25. 2026-09-16 19:45 UTCGHSA enrichment
Show 9 more
  1. 2026-09-16 15:25 UTCEG score recompute
  2. 2026-09-16 15:25 UTCGHSA enrichment
  3. 2026-09-16 14:36 UTCEG score recompute
  4. 2026-09-16 14:36 UTCGHSA enrichment
  5. 2026-09-16 14:08 UTCEPSS rescore
  6. 2026-09-16 09:31 UTCEG score recompute
  7. 2026-09-16 09:31 UTCGHSA enrichment
  8. 2026-09-16 08:42 UTCEG score recompute
  9. 2026-09-16 08:41 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-81634?
CVE-2026-81634 is a high vulnerability published on September 16, 2026. In NLnet Labs Unbound up to and including 1.26.0, a 255 length query name with a large TCP response can lead to a heap buffer overflow during the RRSet canonicalisation routine. This is caused by missing to add the first owner name into the buffer length check. A malicious actor operating a…
When was CVE-2026-81634 disclosed?
CVE-2026-81634 was first published in the National Vulnerability Database on September 16, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-81634 actively exploited?
CVE-2026-81634 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 70.7% of all scored CVEs.
What is the CVSS score of CVE-2026-81634?
CVE-2026-81634 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-81634?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-81634, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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