CVE-2026-44390

MEDIUMNVD 5.35.3—
EchelonGraph scoreMEDIUM confidence

Score 5.3 from GitHub Security Advisory published 2026-05-20. NVD baseline CVSS 5.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
5.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 5.3Exploit: None knownExposed: 0

A fix is available — apply it.

NLnet Labs Unbound up to and including version 1.25.0 has a vulnerability when handling replies with very large RRsets that Unbound needs to perform name compression for. Malicious upstream responses with very large RRsets with records that don't share a suffix above the root can cause Unbound to spend a considerable time applying name compression to downstream replies. This can lead to degraded performance and eventually denial of service in well orchestrated attacks. An adversary can exploit the vulnerability by querying Unbound for the specially crafted contents of a malicious zone with very large RRsets. Before Unbound replies to the query it will try to apply name compression which was an unbounded operation that could lock the CPU until the whole packet was complete. A compression limit was introduced in 1.21.1 for this but it didn't account for the case where records would not share any suffix above the root. That causes Unbound to go in a different code path because of the compression tree lookup failure and eventually not increment the compression counter for those operations. Unbound 1.25.1 contains a patch with a fix that increments the compression counter regardless of the compression tree lookup. This is a complement fix to CVE-2024-8508.

CVSS v3
5.3
EG Score
5.3(medium)
EG Risk
39(Track)
EG Risk 39/100SSVC: 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
Severity53% × 45%
Exploitation1% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
49%
KEV
Not listed

Published

May 20, 2026

Last Modified

September 1, 2026

Advisory Details (1)

Auto-updated May 20, 2026
No patch confirmed yet.
generic
https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-44390.txt

Vendor Advisories for CVE-2026-44390(6)

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

Patch Availability(5)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntuunbound-host (1.24.2-1ubuntu2.1) @ resolute2026-08-25ubuntu
redhatunbound-0:1.16.2-5.12.el8_102026-07-09redhat
redhatunbound-0:1.24.2-3.el9_8.22026-07-08redhat
redhatunbound-0:1.24.2-7.el10_2.22026-07-07redhat
redhatunbound-main-1.25.1-2.hum12026-06-07redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(5 across 5 ecosystems)
Alpine:v3.24(1)
PackageVulnerable rangeFixed inDependents
unbound—1.25.1-r0—
Debian:11(1)
PackageVulnerable rangeFixed inDependents
unbound1.13.1-1 ... 1.25.2-1 (47 versions)——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
unbound1.17.1-2 ... 1.26.0-2 (25 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
unbound1.22.0-2, 1.22.0-2+deb13u1, 1.22.0-2+deb13u21.22.0-2+deb13u3—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
unbound1.22.0-2 ... 1.25.0-1 (8 versions)1.25.1-1—

Weakness Classification(2)

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

Additional Vendor Advisories

(1)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 6× in last 7d / 41× 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.

Showing the most recent 100 of 245 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-44390?
CVE-2026-44390 is a medium vulnerability published on May 20, 2026. NLnet Labs Unbound up to and including version 1.25.0 has a vulnerability when handling replies with very large RRsets that Unbound needs to perform name compression for. Malicious upstream responses with very large RRsets with records that don't share a suffix above the root can cause Unbound to…
When was CVE-2026-44390 disclosed?
CVE-2026-44390 was first published in the National Vulnerability Database on May 20, 2026, with the most recent update on September 1, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-44390 actively exploited?
CVE-2026-44390 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 51.4% of all scored CVEs.
What is the CVSS score of CVE-2026-44390?
CVE-2026-44390 has a CVSS v3 base score of 5.3 (NVD).
How do I remediate CVE-2026-44390?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-44390, 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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