CVE-2026-55973

HIGHPre-NVD 7.57.5—
EchelonGraph scoreHIGH confidence

Score 7.5 from GitHub Security Advisory (severity: HIGH) published 2026-07-22. a secondary CVSS source baseline 7.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — Patch released this week
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.5Exploit: None knownExposed: 0

A fix is available — apply it.

In NLnet Labs Unbound 1.23.0 up to and including 1.25.1, when 'dns-error-reporting: yes' is set, the EDNS Report-Channel option (code 18) from the last upstream response is read and uses the option's length as the length of the agent domain. When a domain name check is performed on the agent domain, the returned lenght is not used and if the agent domain is followed by garbage, those bytes are moved onto the tail of the synthetic '_er.' report query name. That query name is later used in the iterator via a subquery to send out the DNS Error Report and when Unbound tries to walk that query name during 'find_closest_of_type()', it strips labels using the query name length rather than stopping at the embedded root, walks one byte past it, and feeds the first garbage byte to 'dname_query_hash()' as a label length writing over the stack variable 'labuf'. One ordinary upstream response from a delegated zone the attacker controls is sufficient to terminate the daemon.

CVSS v3
7.5
EG Score
7.5(high)
EG Risk
49(Track)
EG Risk 49/100SSVC: 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
Severity75% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
22%
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-2026-55973.txt

Vendor Advisories for CVE-2026-55973(5)

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

Patch Availability(3)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatunbound-0:1.24.2-3.el9_8.42026-08-17redhat
redhatunbound-0:1.24.2-7.el10_2.42026-08-17redhat
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 ... 1.25.2-1 (23 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
unbound1.22.0-2 ... 1.25.2-1 (13 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 40× in last 7d / 157× 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 157 total refreshes for this CVE.

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

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-55973?
CVE-2026-55973 is a high vulnerability published on July 22, 2026. In NLnet Labs Unbound 1.23.0 up to and including 1.25.1, when 'dns-error-reporting: yes' is set, the EDNS Report-Channel option (code 18) from the last upstream response is read and uses the option's length as the length of the agent domain. When a domain name check is performed on the agent…
When was CVE-2026-55973 disclosed?
CVE-2026-55973 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-2026-55973 actively exploited?
CVE-2026-55973 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 78.3% of all scored CVEs.
What is the CVSS score of CVE-2026-55973?
CVE-2026-55973 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-55973?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-55973, 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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