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
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
69%
KEV
Not listed

Published

May 20, 2026

Last Modified

September 1, 2026

Advisory Details (7)

Auto-updated Sep 15, 2026
No patch confirmed yet.
generic
https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-33278.txt
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-2026-33278 - Red Hat Customer Portal

Affected: Red Hat Enterprise Linux 8 or OpenShift Container Platform 4, is affected by this vulnerability and a fix may be released to a

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
https://access.redhat.com/errata/RHSA-2026:19752
redhat Patch Available

Affected: Red Hat Enterprise Linux 10.

https://access.redhat.com/errata/RHSA-2026:23231

Vendor Advisories for CVE-2026-33278(5)

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 (1.24.2-1ubuntu2.1) @ resolute2026-08-25ubuntu
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.

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 8× in last 7d / 53× 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 551 total refreshes for this CVE.

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

Related CVEs(same vendor + same CWE)

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 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-2026-33278 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 31.5% 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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