CVE-2026-56416

MEDIUMPre-NVD 4.84.8—
EchelonGraph scoreMEDIUM confidence

Score 4.8 from GitHub Security Advisory published 2026-07-22. a secondary CVSS source baseline 4.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this week
4.8EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 4.8Exploit: None knownExposed: 0

A fix is available — apply it.

In NLnet Labs Unbound up to and including version 1.25.1, when the validator builds the canonical RDATA form for an RRSIG-covered PX/RP/MINFO/SOA RRset, it computes the address of the second embedded domain name as 'datstart + dname_valid(datstart, ...)' and passes it straight to 'query_dname_tolower()' without checking that a second name is actually present in the RDATA. The wire-format parser accepts multi-dname RRs whose RDATA ends after the first name, so an attacker who runs a DNSSEC-signed authoritative server can deliver a record with an absent second domain name (e.g. SOA record) and cause 'query_dname_tolower()' to walk label-by-label through stale bytes in the per-worker 'env->scratch_buffer', past the end of that heap allocation if 'msg-buffer-size' has been lowered from the default. This leads to heap buffer overflow and on a release build the outcome relies heavily on the contents of the buffer tail and the adjacent heap chunk.

CVSS v3
4.8
EG Score
4.8(medium)
EG Risk
22(Track)
EG Risk 22/100SSVC: 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
Severity48% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
2%
KEV
Not listed

Published

July 22, 2026

Last Modified

July 24, 2026

Advisory Details (1)

Auto-updated Jul 22, 2026
No patch confirmed yet.
generic
https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-56416.txt

Vendor Advisories for CVE-2026-56416(3)

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
redhatunbound-main-1.25.2-0.1.hum12026-07-22redhat

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—1.25.2-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 ... 1.26.0-2 (15 versions)——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
unbound1.22.0-2 ... 1.25.1-1 (9 versions)1.25.2-1—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 23× in last 7d / 92× 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 202 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-56416?
CVE-2026-56416 is a medium vulnerability published on July 22, 2026. In NLnet Labs Unbound up to and including version 1.25.1, when the validator builds the canonical RDATA form for an RRSIG-covered PX/RP/MINFO/SOA RRset, it computes the address of the second embedded domain name as 'datstart + dnamevalid(datstart, ...)' and passes it straight to…
When was CVE-2026-56416 disclosed?
CVE-2026-56416 was first published in the National Vulnerability Database on July 22, 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-2026-56416 actively exploited?
CVE-2026-56416 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 97.6% of all scored CVEs.
What is the CVSS score of CVE-2026-56416?
CVE-2026-56416 has a CVSS v3 base score of 4.8 (NVD).
How do I remediate CVE-2026-56416?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-56416, 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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