CVE-2026-33278

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-05-20. NVD baseline CVSS 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 4 sources updated this week
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 9.8Exploit: None knownExposed: 0

A fix is available — apply it.

NLnet Labs Unbound 1.19.1 up to and including version 1.25.0 has a vulnerability in the DNSSEC validator that enables denial of service and possible remote code execution as a result of deep copying a data structure and erroneously overwriting a destination pointer. An adversary can exploit the vulnerability by controlling a malicious signed zone and querying a vulnerable Unbound. When DS sub-queries need to suspend validation due to NSEC3 computational budget exhaustion (introduced in Unbound 1.19.1), Unbound deep-copies response messages to preserve them across memory region teardown. A struct-assignment bug overwrites the destination's pointer with the source's pointer. After the sub-query region is freed, the resumed validator dereferences this dangling pointer, triggering a crash or potentially enabling arbitrary code execution. Unbound 1.25.1 contains a patch with a fix to preserve the correct pointer when deep copying the data structure.

CVSS v3
9.8
EG Score
9.8(medium)
EG Risk
60(Track)
EG Risk 60/100SSVC: 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
Severity98% × 45%
Exploitation1% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
67%
KEV
Not listed

Published

May 20, 2026

Last Modified

July 24, 2026

Advisory Details (7)

Auto-updated Jul 24, 2026
Patch available. Sources: redhat.
redhat Patch Available

Affected: Red Hat Enterprise Linux 6",

https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33278.json
redhat Patch Available

2479808 – (CVE-2026-33278) CVE-2026-33278 unbound: Unbound DNSSEC Validator Use-After-Free via Deep Copy Pointer Overwrite Leading to DoS and Possible Remote Code Execution

Affected: Red Hat Enterprise Linux 10

https://bugzilla.redhat.com/show_bug.cgi?id=2479808
redhat Patch Available

cve-details

https://access.redhat.com/security/cve/CVE-2026-33278
redhat Patch Available

Affected: Red Hat Enterprise Linux 9.

https://access.redhat.com/errata/RHSA-2026:24369
redhat Patch Available

Affected: Red Hat Enterprise Linux 10.

https://access.redhat.com/errata/RHSA-2026:23231
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:19752
generic
https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-33278.txt

Vendor Advisories for CVE-2026-33278(4)

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

Patch Availability(4)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntuunbound-host (1.13.1-1ubuntu5.15) @ jammy2026-07-26ubuntu
redhatunbound-0:1.24.2-3.el9_8.12026-06-08redhat
redhatunbound-0:1.24.2-7.el10_2.12026-06-04redhat
redhatunbound-main-1.25.1-0.1.hum12026-05-20redhat

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

(2)

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 16× in last 7d / 58× 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 332 total refreshes for this CVE.

  1. 2026-07-27 14:13 UTCEPSS rescore
  2. 2026-07-26 14:54 UTCEPSS rescore
  3. 2026-07-26 14:54 UTCEPSS rescore
  4. 2026-07-26 08:15 UTCEG score recompute
  5. 2026-07-26 08:15 UTCVendor advisory
  6. 2026-07-26 08:15 UTCGHSA enrichment
  7. 2026-07-25 14:18 UTCEPSS rescore
  8. 2026-07-25 14:18 UTCEPSS rescore
  9. 2026-07-24 14:17 UTCEPSS rescore
  10. 2026-07-24 14:17 UTCEPSS rescore
  11. 2026-07-23 14:18 UTCEPSS rescore
  12. 2026-07-23 14:18 UTCEPSS rescore
  13. 2026-07-23 03:09 UTCEG score recompute
  14. 2026-07-22 14:08 UTCEPSS rescore
  15. 2026-07-21 15:24 UTCEPSS rescore
  16. 2026-07-20 17:08 UTCEPSS rescore
  17. 2026-07-19 02:29 UTCEPSS rescore
  18. 2026-07-18 10:04 UTCEPSS rescore
  19. 2026-07-17 22:59 UTCOSV refresh
  20. 2026-07-16 17:03 UTCEPSS rescore
  21. 2026-07-15 16:57 UTCEPSS rescore
  22. 2026-07-15 16:57 UTCEPSS rescore
  23. 2026-07-15 02:25 UTCNVD updateCVSS v3 → 9.8 · severity → CRITICAL
  24. 2026-07-15 02:00 UTCEPSS rescore
  25. 2026-07-15 02:00 UTCEPSS rescore
Show 75 more
  1. 2026-07-15 01:21 UTCMITRE cvelistV5CVSS v3 → 8.1 · severity → HIGH
  2. 2026-07-13 22:30 UTCEPSS rescore
  3. 2026-07-12 05:46 UTCEPSS rescore
  4. 2026-07-11 08:27 UTCEPSS rescore
  5. 2026-07-09 19:10 UTCEPSS rescore
  6. 2026-07-08 15:15 UTCEPSS rescore
  7. 2026-07-07 13:46 UTCEPSS rescore
  8. 2026-07-06 16:27 UTCEPSS rescore
  9. 2026-07-06 16:27 UTCEPSS rescore
  10. 2026-07-06 02:23 UTCEPSS rescore
  11. 2026-07-06 02:23 UTCEPSS rescore
  12. 2026-07-05 02:30 UTCEPSS rescore
  13. 2026-07-04 06:31 UTCEPSS rescore
  14. 2026-07-01 15:06 UTCEPSS rescore
  15. 2026-06-30 23:22 UTCEPSS rescore
  16. 2026-06-29 20:30 UTCVendor advisory
  17. 2026-06-29 20:30 UTCGHSA enrichment
  18. 2026-06-29 14:06 UTCEPSS rescore
  19. 2026-06-29 14:06 UTCEPSS rescore
  20. 2026-06-28 14:07 UTCEPSS rescore
  21. 2026-06-28 14:07 UTCEPSS rescore
  22. 2026-06-28 12:43 UTCVendor advisory
  23. 2026-06-28 12:43 UTCGHSA enrichment
  24. 2026-06-28 08:44 UTCVendor advisory
  25. 2026-06-28 08:44 UTCGHSA enrichment
  26. 2026-06-28 04:56 UTCEPSS rescore
  27. 2026-06-28 04:56 UTCEPSS rescore
  28. 2026-06-28 04:49 UTCVendor advisory
  29. 2026-06-28 04:49 UTCGHSA enrichment
  30. 2026-06-28 00:49 UTCVendor advisory
  31. 2026-06-28 00:49 UTCGHSA enrichment
  32. 2026-06-27 20:17 UTCVendor advisory
  33. 2026-06-27 20:17 UTCGHSA enrichment
  34. 2026-06-27 12:22 UTCVendor advisory
  35. 2026-06-27 12:22 UTCGHSA enrichment
  36. 2026-06-27 07:26 UTCVendor advisory
  37. 2026-06-27 07:26 UTCGHSA enrichment
  38. 2026-06-27 03:08 UTCEPSS rescore
  39. 2026-06-26 23:30 UTCVendor advisory
  40. 2026-06-26 23:30 UTCGHSA enrichment
  41. 2026-06-26 19:35 UTCVendor advisory
  42. 2026-06-26 19:35 UTCGHSA enrichment
  43. 2026-06-26 03:49 UTCVendor advisory
  44. 2026-06-26 03:49 UTCGHSA enrichment
  45. 2026-06-25 20:09 UTCVendor advisory
  46. 2026-06-25 20:09 UTCGHSA enrichment
  47. 2026-06-25 16:15 UTCVendor advisory
  48. 2026-06-25 16:15 UTCGHSA enrichment
  49. 2026-06-25 13:49 UTCEPSS rescore
  50. 2026-06-25 13:49 UTCEPSS rescore
  51. 2026-06-24 14:05 UTCEPSS rescore
  52. 2026-06-23 21:33 UTCEPSS rescore
  53. 2026-06-23 21:33 UTCEPSS rescore
  54. 2026-06-22 14:25 UTCEPSS rescore
  55. 2026-06-22 14:25 UTCEPSS rescore
  56. 2026-06-21 14:56 UTCEPSS rescore
  57. 2026-06-21 14:56 UTCEPSS rescore
  58. 2026-06-21 01:59 UTCEPSS rescore
  59. 2026-06-19 19:25 UTCEPSS rescore
  60. 2026-06-19 19:25 UTCEPSS rescore
  61. 2026-06-18 17:52 UTCEPSS rescore
  62. 2026-06-18 17:52 UTCEPSS rescore
  63. 2026-06-18 03:52 UTCVendor advisory
  64. 2026-06-18 03:52 UTCGHSA enrichment
  65. 2026-06-17 23:58 UTCVendor advisory
  66. 2026-06-17 23:58 UTCGHSA enrichment
  67. 2026-06-17 20:04 UTCVendor advisory
  68. 2026-06-17 20:04 UTCGHSA enrichment
  69. 2026-06-17 17:53 UTCEPSS rescore
  70. 2026-06-17 15:34 UTCVendor advisory
  71. 2026-06-17 15:34 UTCGHSA enrichment
  72. 2026-06-17 11:26 UTCVendor advisory
  73. 2026-06-17 11:26 UTCGHSA enrichment
  74. 2026-06-17 04:04 UTCVendor advisory
  75. 2026-06-17 04:04 UTCGHSA enrichment

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Frequently asked(5)

What is CVE-2026-33278?
CVE-2026-33278 is a critical vulnerability published on May 20, 2026. NLnet Labs Unbound 1.19.1 up to and including version 1.25.0 has a vulnerability in the DNSSEC validator that enables denial of service and possible remote code execution as a result of deep copying a data structure and erroneously overwriting a destination pointer. An adversary can exploit the…
When was CVE-2026-33278 disclosed?
CVE-2026-33278 was first published in the National Vulnerability Database on May 20, 2026, with the most recent update on July 24, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-33278 actively exploited?
CVE-2026-33278 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 33.2% of all scored CVEs.
What is the CVSS score of CVE-2026-33278?
CVE-2026-33278 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-33278?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-33278, 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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