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
68%
KEV
Not listed

Published

May 20, 2026

Last Modified

August 25, 2026

Advisory Details (7)

Auto-updated Aug 25, 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-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
generic
https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-33278.txt
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 ... 1.25.2-1 (23 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 27× in last 7d / 193× 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 524 total refreshes for this CVE.

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

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 August 25, 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 32.3% 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.

Dependency Blast Radius

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