CVE-2026-55973

HIGHPre-NVD 7.57.5—
EchelonGraph scoreMEDIUM 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(medium)
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
21%
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(6)

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

Patch Availability(5)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatrhcos-4.22.9.8.202609081748-02026-09-15redhat
redhatrhcos-4.22.9.8.202608251819-02026-09-01redhat
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 ... 1.26.0-2 (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.

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 28× in last 7d / 117× 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 274 total refreshes for this CVE.

  1. 2026-09-18 22:41 UTCEG score recompute
  2. 2026-09-18 22:41 UTCVendor advisory
  3. 2026-09-18 22:41 UTCGHSA enrichment
  4. 2026-09-18 19:28 UTCEPSS rescore
  5. 2026-09-18 03:11 UTCEG score recompute
  6. 2026-09-18 03:11 UTCVendor advisory
  7. 2026-09-18 03:11 UTCGHSA enrichment
  8. 2026-09-17 19:31 UTCEPSS rescore
  9. 2026-09-17 02:12 UTCEG score recompute
  10. 2026-09-17 02:12 UTCVendor advisory
  11. 2026-09-17 02:12 UTCGHSA enrichment
  12. 2026-09-16 14:08 UTCEPSS rescore
  13. 2026-09-16 07:04 UTCEG score recompute
  14. 2026-09-16 07:04 UTCVendor advisory
  15. 2026-09-16 07:04 UTCGHSA enrichment
  16. 2026-09-16 05:15 UTCEPSS rescore
  17. 2026-09-15 03:11 UTCEPSS rescore
  18. 2026-09-14 10:45 UTCVendor advisory
  19. 2026-09-14 10:45 UTCGHSA enrichment
  20. 2026-09-13 22:26 UTCEG score recompute
  21. 2026-09-13 22:26 UTCVendor advisory
  22. 2026-09-13 22:26 UTCGHSA enrichment
  23. 2026-09-13 16:47 UTCEPSS rescore
  24. 2026-09-13 07:16 UTCVendor advisory
  25. 2026-09-13 07:16 UTCGHSA enrichment
Show 75 more
  1. 2026-09-12 18:58 UTCEG score recompute
  2. 2026-09-12 18:58 UTCVendor advisory
  3. 2026-09-12 18:58 UTCGHSA enrichment
  4. 2026-09-12 06:40 UTCVendor advisory
  5. 2026-09-12 06:40 UTCGHSA enrichment
  6. 2026-09-11 17:52 UTCEG score recompute
  7. 2026-09-11 17:52 UTCVendor advisory
  8. 2026-09-11 17:52 UTCGHSA enrichment
  9. 2026-09-11 14:53 UTCEPSS rescore
  10. 2026-09-10 21:38 UTCEG score recompute
  11. 2026-09-10 21:38 UTCVendor advisory
  12. 2026-09-10 21:38 UTCGHSA enrichment
  13. 2026-09-10 09:35 UTCEPSS rescore
  14. 2026-09-09 09:17 UTCEG score recompute
  15. 2026-09-09 09:17 UTCVendor advisory
  16. 2026-09-09 09:17 UTCGHSA enrichment
  17. 2026-09-08 22:01 UTCEPSS rescore
  18. 2026-09-07 21:42 UTCEG score recompute
  19. 2026-09-07 21:42 UTCVendor advisory
  20. 2026-09-07 21:42 UTCGHSA enrichment
  21. 2026-09-07 16:01 UTCEPSS rescore
  22. 2026-09-06 13:47 UTCEPSS rescore
  23. 2026-09-06 08:43 UTCVendor advisory
  24. 2026-09-06 08:43 UTCGHSA enrichment
  25. 2026-09-05 19:35 UTCEG score recompute
  26. 2026-09-05 19:35 UTCVendor advisory
  27. 2026-09-05 19:35 UTCGHSA enrichment
  28. 2026-09-05 07:15 UTCEG score recompute
  29. 2026-09-05 07:15 UTCVendor advisory
  30. 2026-09-05 07:15 UTCGHSA enrichment
  31. 2026-09-04 13:56 UTCEG score recompute
  32. 2026-09-04 13:56 UTCVendor advisory
  33. 2026-09-04 13:56 UTCGHSA enrichment
  34. 2026-09-04 05:07 UTCEPSS rescore
  35. 2026-09-02 14:12 UTCEPSS rescore
  36. 2026-09-01 23:41 UTCEG score recompute
  37. 2026-09-01 23:41 UTCVendor advisory
  38. 2026-09-01 23:41 UTCGHSA enrichment
  39. 2026-09-01 13:54 UTCEPSS rescore
  40. 2026-09-01 04:40 UTCEPSS rescore
  41. 2026-08-31 01:31 UTCEG score recompute
  42. 2026-08-31 01:31 UTCVendor advisory
  43. 2026-08-31 01:31 UTCGHSA enrichment
  44. 2026-08-30 19:17 UTCEPSS rescore
  45. 2026-08-30 13:13 UTCEG score recompute
  46. 2026-08-30 13:13 UTCVendor advisory
  47. 2026-08-30 13:13 UTCGHSA enrichment
  48. 2026-08-30 01:22 UTCEPSS rescore
  49. 2026-08-30 00:55 UTCEG score recompute
  50. 2026-08-30 00:55 UTCVendor advisory
  51. 2026-08-30 00:55 UTCGHSA enrichment
  52. 2026-08-28 21:41 UTCEPSS rescore
  53. 2026-08-27 21:10 UTCVendor advisory
  54. 2026-08-27 21:10 UTCGHSA enrichment
  55. 2026-08-27 03:29 UTCVendor advisory
  56. 2026-08-27 03:29 UTCGHSA enrichment
  57. 2026-08-26 15:10 UTCEG score recompute
  58. 2026-08-26 15:10 UTCVendor advisory
  59. 2026-08-26 15:10 UTCGHSA enrichment
  60. 2026-08-26 14:46 UTCEPSS rescore
  61. 2026-08-26 02:46 UTCVendor advisory
  62. 2026-08-26 02:46 UTCGHSA enrichment
  63. 2026-08-25 14:28 UTCEG score recompute
  64. 2026-08-25 14:28 UTCVendor advisory
  65. 2026-08-25 14:28 UTCGHSA enrichment
  66. 2026-08-25 13:49 UTCEPSS rescore
  67. 2026-08-25 01:42 UTCEG score recompute
  68. 2026-08-25 01:42 UTCVendor advisory
  69. 2026-08-25 01:42 UTCGHSA enrichment
  70. 2026-08-24 13:25 UTCEG score recompute
  71. 2026-08-24 13:25 UTCVendor advisory
  72. 2026-08-24 13:24 UTCGHSA enrichment
  73. 2026-08-24 01:05 UTCVendor advisory
  74. 2026-08-24 01:05 UTCGHSA enrichment
  75. 2026-08-23 12:47 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 79.2% 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.

Dependency Blast Radius

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