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
5.3
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 1%CVSS: 5.3Exploit: NoneExposed: 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)
EPSS
42.5%
KEV
Not listed

Published

May 20, 2026

Last Modified

June 30, 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(2)

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

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntuunbound-host (1.24.2-1ubuntu2.1) @ resolute2026-06-29ubuntu

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.

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 7× in last 7d / 62× 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 130 total refreshes for this CVE.

  1. 2026-07-11 08:27 UTCEPSS rescore
  2. 2026-07-09 19:10 UTCEPSS rescore
  3. 2026-07-08 15:16 UTCEPSS rescore
  4. 2026-07-07 13:46 UTCEPSS rescore
  5. 2026-07-06 16:27 UTCEPSS rescore
  6. 2026-07-06 02:23 UTCEPSS rescore
  7. 2026-07-05 02:30 UTCEPSS rescore
  8. 2026-07-04 06:31 UTCEPSS rescore
  9. 2026-07-01 15:07 UTCEPSS rescore
  10. 2026-06-30 23:22 UTCEPSS rescore
  11. 2026-06-29 20:30 UTCEG score recompute
  12. 2026-06-29 20:30 UTCVendor advisory
  13. 2026-06-29 20:30 UTCGHSA enrichment
  14. 2026-06-29 14:06 UTCEPSS rescore
  15. 2026-06-28 14:07 UTCEPSS rescore
  16. 2026-06-28 04:56 UTCEPSS rescore
  17. 2026-06-27 20:48 UTCEG score recompute
  18. 2026-06-27 20:48 UTCVendor advisory
  19. 2026-06-27 20:48 UTCGHSA enrichment
  20. 2026-06-27 03:08 UTCEPSS rescore
  21. 2026-06-26 19:35 UTCEG score recompute
  22. 2026-06-26 19:35 UTCVendor advisory
  23. 2026-06-26 19:35 UTCGHSA enrichment
  24. 2026-06-25 16:08 UTCEG score recompute
  25. 2026-06-25 16:08 UTCVendor advisory
Show 75 more
  1. 2026-06-25 16:08 UTCGHSA enrichment
  2. 2026-06-25 13:49 UTCEPSS rescore
  3. 2026-06-25 13:49 UTCEPSS rescore
  4. 2026-06-24 14:05 UTCEPSS rescore
  5. 2026-06-23 21:33 UTCEPSS rescore
  6. 2026-06-22 14:25 UTCEPSS rescore
  7. 2026-06-22 14:25 UTCEPSS rescore
  8. 2026-06-21 14:56 UTCEPSS rescore
  9. 2026-06-21 14:56 UTCEPSS rescore
  10. 2026-06-21 01:59 UTCEPSS rescore
  11. 2026-06-19 19:25 UTCEPSS rescore
  12. 2026-06-18 17:52 UTCEPSS rescore
  13. 2026-06-18 17:52 UTCEPSS rescore
  14. 2026-06-18 02:54 UTCEG score recompute
  15. 2026-06-18 02:54 UTCVendor advisory
  16. 2026-06-18 02:54 UTCGHSA enrichment
  17. 2026-06-17 17:53 UTCEPSS rescore
  18. 2026-06-17 01:48 UTCEG score recompute
  19. 2026-06-17 01:48 UTCVendor advisory
  20. 2026-06-17 01:48 UTCGHSA enrichment
  21. 2026-06-16 17:52 UTCEPSS rescore
  22. 2026-06-16 00:42 UTCEG score recompute
  23. 2026-06-16 00:42 UTCVendor advisory
  24. 2026-06-16 00:42 UTCGHSA enrichment
  25. 2026-06-15 17:49 UTCEPSS rescore
  26. 2026-06-14 23:35 UTCEG score recompute
  27. 2026-06-14 23:35 UTCVendor advisory
  28. 2026-06-14 23:35 UTCGHSA enrichment
  29. 2026-06-13 23:00 UTCEPSS rescore
  30. 2026-06-13 22:30 UTCEG score recompute
  31. 2026-06-13 22:30 UTCVendor advisory
  32. 2026-06-13 22:30 UTCGHSA enrichment
  33. 2026-06-12 23:12 UTCEPSS rescore
  34. 2026-06-12 23:12 UTCEPSS rescore
  35. 2026-06-12 15:01 UTCEG score recompute
  36. 2026-06-12 15:01 UTCVendor advisory
  37. 2026-06-12 15:01 UTCGHSA enrichment
  38. 2026-06-11 14:00 UTCEPSS rescore
  39. 2026-06-11 13:55 UTCEG score recompute
  40. 2026-06-11 13:55 UTCVendor advisory
  41. 2026-06-11 13:55 UTCGHSA enrichment
  42. 2026-06-10 22:18 UTCEPSS rescore
  43. 2026-06-10 13:22 UTCEPSS rescore
  44. 2026-06-10 13:22 UTCEPSS rescore
  45. 2026-06-10 12:49 UTCEG score recompute
  46. 2026-06-10 12:49 UTCVendor advisory
  47. 2026-06-10 12:49 UTCGHSA enrichment
  48. 2026-06-09 11:44 UTCEG score recompute
  49. 2026-06-09 11:44 UTCVendor advisory
  50. 2026-06-09 11:43 UTCGHSA enrichment
  51. 2026-06-08 14:17 UTCEPSS rescore
  52. 2026-06-08 14:17 UTCEPSS rescore
  53. 2026-06-08 10:37 UTCEG score recompute
  54. 2026-06-08 10:37 UTCVendor advisory
  55. 2026-06-08 10:37 UTCGHSA enrichment
  56. 2026-06-07 15:25 UTCEPSS rescore
  57. 2026-06-07 15:25 UTCEPSS rescore
  58. 2026-06-07 09:31 UTCEG score recompute
  59. 2026-06-07 09:31 UTCVendor advisory
  60. 2026-06-07 09:31 UTCGHSA enrichment
  61. 2026-06-06 13:47 UTCEPSS rescore
  62. 2026-06-06 13:47 UTCEPSS rescore
  63. 2026-06-06 08:25 UTCEG score recompute
  64. 2026-06-06 08:25 UTCVendor advisory
  65. 2026-06-06 08:25 UTCGHSA enrichment
  66. 2026-06-05 22:47 UTCEPSS rescore
  67. 2026-06-05 07:20 UTCEG score recompute
  68. 2026-06-05 07:20 UTCVendor advisory
  69. 2026-06-05 07:20 UTCGHSA enrichment
  70. 2026-06-05 06:10 UTCEPSS rescore
  71. 2026-06-05 06:10 UTCEPSS rescore
  72. 2026-06-04 13:12 UTCEPSS rescore
  73. 2026-06-04 13:12 UTCEPSS rescore
  74. 2026-06-04 06:14 UTCEG score recompute
  75. 2026-06-04 06:14 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 June 30, 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 42.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
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.

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