CVE-2026-33278

CRITICALNVD 9.89.8
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to NVD's CVSS score.

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, GitHub Security Advisory, NVD CVSS v3
Trending — 4 sources updated this week

Also known asEUVD-2026-31075 (ENISA EUVD) · GHSA-m234-r435-cxjw (GitHub Security Advisories)Source: ENISA EUVD

9.8EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1.4%CVSS: 9.8Exploit: None knownExposed services: Not assessed

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
9.8CRITICALmedium confidence
EG Risk
60
EG Risk 60/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity98% × 45%
Impact severity (EG Severity): CVSS 9.8 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation1.4% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
1.4%
EPSS %ILE
72nd
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (9.8): severity, escalated by confirmed exploitation. This CVE's 9.8 is its impact severity (EG Severity), not escalated.

EG Severity
9.8 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
1.4% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-01). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 3 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)3 days if the affected system is publicly exposed; 60 days if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

May 20, 2026

Last Modified

September 1, 2026

Advisory Details (7)

Auto-updated Oct 31, 2026
Patch available.
Red HatMentions a patch (unverified)

Affected: Red Hat Enterprise Linux 6",

https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33278.json
Red HatMentions a patch (unverified)

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
Red HatMentions a patch (unverified)

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
Red HatMentions a patch (unverified)

Affected: Red Hat Enterprise Linux 9.

https://access.redhat.com/errata/RHSA-2026:24369
Red HatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:19752
Red HatMentions a patch (unverified)

Affected: Red Hat Enterprise Linux 10.

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

Patch Availability(4)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntuunbound-host (1.24.2-1ubuntu2.1) @ resolute2026-11-01ubuntu
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

(7 across 7 ecosystems)
Alpine:v3.22(1)
PackageVulnerable rangeFix by version rangeDependents
unbound—
  • 1.19.1 up to 1.25.2-r0: fixed in 1.25.2-r0
—
Alpine:v3.23(1)
PackageVulnerable rangeFix by version rangeDependents
unbound—
  • 1.19.1 up to 1.25.2-r0: fixed in 1.25.2-r0
—
Alpine:v3.24(1)
PackageVulnerable rangeFix by version rangeDependents
unbound—
  • 1.19.1 up to 1.25.1-r0: fixed in 1.25.1-r0
—
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
unbound1.13.1-1 ... 1.25.2-1 (47 versions)
  • every version on: no fix on record
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
unbound1.17.1-2 ... 1.26.1-1 (26 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
unbound1.22.0-2, 1.22.0-2+deb13u1, 1.22.0-2+deb13u2
  • every version up to 1.22.0-2+deb13u3: fixed in 1.22.0-2+deb13u3
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
unbound1.22.0-2 ... 1.25.0-1 (8 versions)
  • every version up to 1.25.1-1: fixed in 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 25× in last 7d / 96× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 100 of 654 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 554 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-01 20:04 UTCEG score recompute
  2. 2026-11-01 20:04 UTCVendor advisory
  3. 2026-11-01 20:04 UTCGHSA enrichmentGHSA-m234-r435-cxjw · GitHub severity CRITICAL · GitHub CVSS 9.8
  4. 2026-11-01 16:34 UTCEPSS rescoreEPSS 1.4% · 72nd percentile
  5. 2026-10-31 18:30 UTCEG score recompute
  6. 2026-10-31 18:30 UTCVendor advisory
  7. 2026-10-31 18:30 UTCGHSA enrichmentGHSA-m234-r435-cxjw · GitHub severity CRITICAL · GitHub CVSS 9.8
  8. 2026-10-31 16:32 UTCEPSS rescoreEPSS 1.4% · 72nd percentile
  9. 2026-10-30 16:46 UTCEG score recompute
  10. 2026-10-30 16:46 UTCVendor advisory
  11. 2026-10-30 16:46 UTCGHSA enrichmentGHSA-m234-r435-cxjw · GitHub severity CRITICAL · GitHub CVSS 9.8
  12. 2026-10-30 16:34 UTCEPSS rescoreEPSS 1.4% · 72nd percentile
  13. 2026-10-29 16:33 UTCEPSS rescoreEPSS 1.4% · 72nd percentile
  14. 2026-10-29 15:14 UTCEG score recompute
  15. 2026-10-29 15:14 UTCVendor advisory
  16. 2026-10-29 15:14 UTCGHSA enrichmentGHSA-m234-r435-cxjw · GitHub severity CRITICAL · GitHub CVSS 9.8
  17. 2026-10-28 16:32 UTCEPSS rescoreEPSS 1.4% · 72nd percentile
  18. 2026-10-28 13:41 UTCEG score recompute
  19. 2026-10-28 13:41 UTCVendor advisory
  20. 2026-10-28 13:40 UTCGHSA enrichmentGHSA-m234-r435-cxjw · GitHub severity CRITICAL · GitHub CVSS 9.8
  21. 2026-10-27 16:31 UTCEPSS rescoreEPSS 1.4% · 72nd percentile
  22. 2026-10-27 11:55 UTCEG score recompute
  23. 2026-10-27 11:55 UTCVendor advisory
  24. 2026-10-27 11:55 UTCGHSA enrichmentGHSA-m234-r435-cxjw · GitHub severity CRITICAL · GitHub CVSS 9.8
  25. 2026-10-26 16:31 UTCEPSS rescoreEPSS 1.4% · 72nd percentile
Show 75 more
  1. 2026-10-26 10:22 UTCEG score recompute
  2. 2026-10-26 10:22 UTCVendor advisory
  3. 2026-10-26 10:22 UTCGHSA enrichmentGHSA-m234-r435-cxjw · GitHub severity CRITICAL · GitHub CVSS 9.8
  4. 2026-10-25 16:32 UTCEPSS rescoreEPSS 1.4% · 72nd percentile
  5. 2026-10-25 14:35 UTCEG score recompute
  6. 2026-10-25 08:50 UTCEG score recompute
  7. 2026-10-25 08:50 UTCVendor advisory
  8. 2026-10-25 08:50 UTCGHSA enrichmentGHSA-m234-r435-cxjw · GitHub severity CRITICAL · GitHub CVSS 9.8
  9. 2026-10-24 16:32 UTCEPSS rescoreEPSS 1.1% · 66th percentile
  10. 2026-10-24 07:17 UTCEG score recompute
  11. 2026-10-24 07:17 UTCVendor advisory
  12. 2026-10-24 07:17 UTCGHSA enrichmentGHSA-m234-r435-cxjw · GitHub severity CRITICAL · GitHub CVSS 9.8
  13. 2026-10-23 16:31 UTCEPSS rescoreEPSS 1.1% · 66th percentile
  14. 2026-10-23 05:44 UTCEG score recompute
  15. 2026-10-23 05:44 UTCVendor advisory
  16. 2026-10-23 05:44 UTCGHSA enrichmentGHSA-m234-r435-cxjw · GitHub severity CRITICAL · GitHub CVSS 9.8
  17. 2026-10-22 16:34 UTCEPSS rescoreEPSS 1.1% · 66th percentile
  18. 2026-10-22 04:10 UTCEG score recompute
  19. 2026-10-22 04:10 UTCVendor advisory
  20. 2026-10-22 04:10 UTCGHSA enrichmentGHSA-m234-r435-cxjw · GitHub severity CRITICAL · GitHub CVSS 9.8
  21. 2026-10-21 16:32 UTCEPSS rescoreEPSS 1.1% · 66th percentile
  22. 2026-10-21 02:33 UTCEG score recompute
  23. 2026-10-21 02:33 UTCVendor advisory
  24. 2026-10-21 02:33 UTCGHSA enrichmentGHSA-m234-r435-cxjw · GitHub severity CRITICAL · GitHub CVSS 9.8
  25. 2026-10-20 16:33 UTCEPSS rescoreEPSS 1.1% · 65th percentile
  26. 2026-10-20 01:00 UTCEG score recompute
  27. 2026-10-20 01:00 UTCVendor advisory
  28. 2026-10-20 01:00 UTCGHSA enrichmentGHSA-m234-r435-cxjw · GitHub severity CRITICAL · GitHub CVSS 9.8
  29. 2026-10-19 16:31 UTCEPSS rescoreEPSS 1.1% · 65th percentile
  30. 2026-10-18 23:25 UTCEG score recompute
  31. 2026-10-18 23:25 UTCVendor advisory
  32. 2026-10-18 23:25 UTCGHSA enrichmentGHSA-m234-r435-cxjw · GitHub severity CRITICAL · GitHub CVSS 9.8
  33. 2026-10-18 16:31 UTCEPSS rescoreEPSS 1.1% · 65th percentile
  34. 2026-10-18 03:46 UTCEG score recompute
  35. 2026-10-17 21:51 UTCEG score recompute
  36. 2026-10-17 21:51 UTCVendor advisory
  37. 2026-10-17 21:50 UTCGHSA enrichmentGHSA-m234-r435-cxjw · GitHub severity CRITICAL · GitHub CVSS 9.8
  38. 2026-10-17 16:34 UTCEPSS rescoreEPSS 1.1% · 65th percentile
  39. 2026-10-16 20:17 UTCEG score recompute
  40. 2026-10-16 20:17 UTCVendor advisory
  41. 2026-10-16 20:17 UTCGHSA enrichmentGHSA-m234-r435-cxjw · GitHub severity CRITICAL · GitHub CVSS 9.8
  42. 2026-10-16 16:41 UTCEPSS rescoreEPSS 1.1% · 65th percentile
  43. 2026-10-15 17:44 UTCEG score recompute
  44. 2026-10-15 17:44 UTCVendor advisory
  45. 2026-10-15 17:44 UTCGHSA enrichmentGHSA-m234-r435-cxjw · GitHub severity CRITICAL · GitHub CVSS 9.8
  46. 2026-10-15 16:32 UTCEPSS rescoreEPSS 1.1% · 65th percentile
  47. 2026-10-14 16:32 UTCEPSS rescoreEPSS 1.1% · 65th percentile
  48. 2026-10-14 11:37 UTCEG score recompute
  49. 2026-10-14 11:37 UTCVendor advisory
  50. 2026-10-14 11:37 UTCGHSA enrichmentGHSA-m234-r435-cxjw · GitHub severity CRITICAL · GitHub CVSS 9.8
  51. 2026-10-13 16:34 UTCEPSS rescoreEPSS 1.1% · 65th percentile
  52. 2026-10-13 10:02 UTCEG score recompute
  53. 2026-10-13 10:02 UTCVendor advisory
  54. 2026-10-13 10:02 UTCGHSA enrichmentGHSA-m234-r435-cxjw · GitHub severity CRITICAL · GitHub CVSS 9.8
  55. 2026-10-12 16:34 UTCEPSS rescoreEPSS 1.1% · 65th percentile
  56. 2026-10-12 16:13 UTCEG score recompute
  57. 2026-10-12 08:28 UTCVendor advisory
  58. 2026-10-12 08:27 UTCGHSA enrichmentGHSA-m234-r435-cxjw · GitHub severity CRITICAL · GitHub CVSS 9.8
  59. 2026-10-11 19:55 UTCEG score recompute
  60. 2026-10-11 17:09 UTCEG score recompute
  61. 2026-10-11 14:36 UTCEG score recompute
  62. 2026-10-11 13:48 UTCEPSS rescoreEPSS 1.1% · 65th percentile
  63. 2026-10-10 20:00 UTCEPSS rescoreEPSS 1.1% · 65th percentile
  64. 2026-10-10 00:55 UTCOSV refresh
  65. 2026-10-09 20:07 UTCEPSS rescoreEPSS 1.1% · 65th percentile
  66. 2026-10-08 17:12 UTCEPSS rescoreEPSS 1.1% · 65th percentile
  67. 2026-10-07 23:47 UTCEPSS rescoreEPSS 1.1% · 65th percentile
  68. 2026-10-06 15:17 UTCEPSS rescoreEPSS 1.1% · 65th percentile
  69. 2026-10-05 17:42 UTCEPSS rescoreEPSS 1.1% · 65th percentile
  70. 2026-10-04 23:22 UTCEPSS rescoreEPSS 1.1% · 65th percentile
  71. 2026-10-03 14:25 UTCEPSS rescoreEPSS 1.1% · 65th percentile
  72. 2026-10-01 19:49 UTCEPSS rescoreEPSS 1.1% · 65th percentile
  73. 2026-09-30 15:03 UTCEPSS rescoreEPSS 1.1% · 65th percentile
  74. 2026-09-28 13:51 UTCEPSS rescoreEPSS 1.1% · 65th percentile
  75. 2026-09-27 13:48 UTCEPSS rescoreEPSS 1.1% · 65th percentile

Frequently asked(5)

What is CVE-2026-33278?
CVE-2026-33278 is a critical-severity vulnerability; its CVE record was 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 made public?
CVE-2026-33278 was made public on May 20, 2026: that is the date its CVE record's CNA, NLnet Labs, gives for when the vulnerability was made public. The CVE record itself was published on May 20, 2026. EchelonGraph's copy of the record carries a last-modified date of September 1, 2026; the record at its source may have been updated since.
Is CVE-2026-33278 actively exploited?
CVE-2026-33278 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1.4% probability of exploitation in the next 30 days (72nd percentile of EPSS-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?
A fix for CVE-2026-33278 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-33278 are linked in the Vendor Advisories panel on this page.

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