CVE-2026-18664

CRITICALNVD 9.19.1
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to NVD's CVSS score.

Score 9.1 from GitHub Security Advisory (severity: HIGH) published 2026-09-01. NVD baseline CVSS 9.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3
Trending — 3 sources updated this week
9.1EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 9.1Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

Fixed versions, as the CVE record's CNA (NLnet Labs) states them: "This issue is fixed in 4.15.1 and all later versions."

When ranges are used for access control (i.e. of the form 1.2.3.4-1.2.3.25), because NSD wrongly compares the IP address with the range on little endian systems, IPs that were meant to be allowed may be denied, and, IPs that were meant to be denied access could be allowed. An IPv4 address is compared with IPv4 ranges as unsigned 32 bit numbers directly with the endianness of the host, but the values to compare are in network byte order (big-endian). With IPv6 addresses the comparison is done in 4 times a unsigned 32 bit number comparison, again with the endianness of the host where all values are actually in network bye order.

CVSS v3
9.1
EG Score
9.1CRITICALmedium confidence
EG Risk
41
EG Risk 41/100

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 (value × EchelonGraph’s weight)
Severity91% × 45%
The EG Score, 9.1 of 10.
Exploitation0.3% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at every mission impact level.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.3%
EPSS %ILE
16th
KEV
Not listed

SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

August 26, 2026

Last Modified

September 8, 2026

Advisory Details (1)

Auto-updated Sep 15, 2026
Patch available.
Web page
https://www.nlnetlabs.nl/downloads/nsd/CVE-2026-18664.txt

Vendor Advisories for CVE-2026-18664(1)

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

Affected Packages

(3 across 3 ecosystems)
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
nsd4.10.1-1 ... 4.9.1-1 (25 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
nsd4.12.0-1 ... 4.15.2-1 (16 versions)
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
nsd4.12.0-1 ... 4.15.0~rc1-1 (14 versions)
  • every version up to 4.15.1-1: fixed in 4.15.1-1
—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 27× in last 7d / 181× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 100 of 268 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 168 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-14 02:48 UTCEG score recompute
  2. 2026-10-14 02:48 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  3. 2026-10-13 16:33 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  4. 2026-10-12 22:54 UTCEG score recompute
  5. 2026-10-12 22:54 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  6. 2026-10-12 16:33 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  7. 2026-10-12 16:27 UTCEG score recompute
  8. 2026-10-12 09:27 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  9. 2026-10-11 20:07 UTCEG score recompute
  10. 2026-10-11 17:20 UTCEG score recompute
  11. 2026-10-11 14:52 UTCEG score recompute
  12. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  13. 2026-10-10 19:59 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  14. 2026-10-10 15:18 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  15. 2026-10-10 11:08 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  16. 2026-10-10 06:51 UTCEG score recompute
  17. 2026-10-10 06:51 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  18. 2026-10-09 20:06 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  19. 2026-10-09 07:26 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  20. 2026-10-09 03:30 UTCEG score recompute
  21. 2026-10-09 03:29 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  22. 2026-10-08 17:11 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  23. 2026-10-08 09:58 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  24. 2026-10-08 06:01 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  25. 2026-10-08 02:02 UTCEG score recompute
Show 75 more
  1. 2026-10-08 02:02 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  2. 2026-10-07 23:47 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  3. 2026-10-07 09:07 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  4. 2026-10-07 05:04 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  5. 2026-10-07 01:08 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  6. 2026-10-06 20:44 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  7. 2026-10-06 16:00 UTCEG score recompute
  8. 2026-10-06 15:59 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  9. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  10. 2026-10-06 11:52 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  11. 2026-10-06 07:37 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  12. 2026-10-06 01:47 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  13. 2026-10-05 20:51 UTCEG score recompute
  14. 2026-10-05 20:51 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  15. 2026-10-05 17:42 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  16. 2026-10-05 16:56 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  17. 2026-10-05 11:38 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  18. 2026-10-05 07:42 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  19. 2026-10-05 03:45 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  20. 2026-10-04 23:39 UTCEG score recompute
  21. 2026-10-04 23:39 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  22. 2026-10-04 23:21 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  23. 2026-10-04 19:43 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  24. 2026-10-04 13:52 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  25. 2026-10-04 09:56 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  26. 2026-10-04 05:59 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  27. 2026-10-04 02:03 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  28. 2026-10-03 20:13 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  29. 2026-10-03 16:13 UTCEG score recompute
  30. 2026-10-03 16:13 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  31. 2026-10-03 06:56 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  32. 2026-10-03 02:59 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  33. 2026-10-02 23:01 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  34. 2026-10-02 18:52 UTCEG score recompute
  35. 2026-10-02 18:52 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  36. 2026-10-02 14:48 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  37. 2026-10-02 10:20 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  38. 2026-10-02 06:23 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  39. 2026-10-02 01:16 UTCEG score recompute
  40. 2026-10-02 01:16 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  41. 2026-10-01 19:58 UTCEG score recompute
  42. 2026-10-01 19:58 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  43. 2026-10-01 19:49 UTCEPSS rescoreEPSS 0.3% · 15th percentile
  44. 2026-10-01 13:26 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  45. 2026-10-01 09:29 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  46. 2026-10-01 05:33 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  47. 2026-10-01 01:05 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  48. 2026-09-30 20:00 UTCEG score recompute
  49. 2026-09-30 20:00 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  50. 2026-09-30 15:02 UTCEPSS rescoreEPSS 0.3% · 15th percentile
  51. 2026-09-30 10:10 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  52. 2026-09-30 06:12 UTCEG score recompute
  53. 2026-09-30 06:12 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  54. 2026-09-29 15:20 UTCEPSS rescoreEPSS 0.3% · 15th percentile
  55. 2026-09-29 12:35 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  56. 2026-09-29 05:22 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  57. 2026-09-29 01:26 UTCEG score recompute
  58. 2026-09-29 01:26 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  59. 2026-09-28 21:22 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  60. 2026-09-28 14:09 UTCEG score recompute
  61. 2026-09-28 14:09 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  62. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.3% · 15th percentile
  63. 2026-09-28 10:11 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  64. 2026-09-28 06:14 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  65. 2026-09-28 02:18 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  66. 2026-09-27 22:22 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  67. 2026-09-27 18:25 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  68. 2026-09-27 14:28 UTCEG score recompute
  69. 2026-09-27 14:28 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  70. 2026-09-27 13:47 UTCEPSS rescoreEPSS 0.3% · 15th percentile
  71. 2026-09-27 10:05 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  72. 2026-09-27 06:09 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  73. 2026-09-27 02:13 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1
  74. 2026-09-26 21:13 UTCEG score recompute
  75. 2026-09-26 21:13 UTCGHSA enrichmentGHSA-fw9f-54cp-j7fc · GitHub severity HIGH · GitHub CVSS 9.1

Related CVEs(same product + same CWE)

Frequently asked(5)

What is CVE-2026-18664?
CVE-2026-18664 is a critical-severity vulnerability; its CVE record was published on August 26, 2026. When ranges are used for access control (i.e. of the form 1.2.3.4-1.2.3.25), because NSD wrongly compares the IP address with the range on little endian systems, IPs that were meant to be allowed may be denied, and, IPs that were meant to be denied access could be allowed. An IPv4 address is…
When was CVE-2026-18664 made public?
CVE-2026-18664 was made public on August 26, 2026: that is the date its CVE record's CNA, NLnet Labs, gives for when the vulnerability was made public. The CVE record itself was published on August 26, 2026. EchelonGraph's copy of the record carries a last-modified date of September 8, 2026; the record at its source may have been updated since.
Is CVE-2026-18664 actively exploited?
CVE-2026-18664 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (16th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-18664?
CVE-2026-18664 has a CVSS v3 base score of 9.1 (NVD).
How do I remediate CVE-2026-18664?
A fix for CVE-2026-18664 is available: update to the fixed version the vendor names in its advisory. Fixed versions, as the CVE record's CNA (NLnet Labs) states them: "This issue is fixed in 4.15.1 and all later versions." The vendor advisories EchelonGraph has for CVE-2026-18664 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-18664

Explore →

Is Your Infrastructure Affected by CVE-2026-18664?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Book a Demo →Browse All CVEs