CVE-2026-55717

MEDIUMPre-NVD 5.95.9—
EchelonGraph scoreMEDIUM confidence

Score 5.9 from GitHub Security Advisory published 2026-07-22. a secondary CVSS source baseline 5.9; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this week
5.9EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.9Exploit: None knownExposed: 0

A fix is available — apply it.

In NLnet Labs Unbound 1.10.0 up to and including 1.25.1, when 'serve-expired: yes' is set together with a 'response-ip: redirect' /'response-ip-data: CNAME ' rule (or the RPZ 'rpz-cname-override' equivalent), a remote client who controls any delegated domain can crash the daemon. The serve-expired-client-timeout callback runs a two-pass loop to chase the respip-generated CNAME alias; on the second pass it resets 'alias_rrset' but not 'partial_rep'. Later, this inconsistency leads to a NULL pointer dereference and an eventual crash. A malicious actor can exploit the vulnerability by controlling any zone that replies with an A/AAAA record that falls inside the configured response-ip/rpz subnet. By delaying the answer when the previous record has expired, the vulnerable path of 'serve-expired-client-timeout' is taken leading to denial of service via the server crash.

CVSS v3
5.9
EG Score
5.9(medium)
EG Risk
27(Track)
EG Risk 27/100SSVC: 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
Severity59% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
15%
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-2026-55717.txt

Vendor Advisories for CVE-2026-55717(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 ... 1.25.2-1 (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 25× in last 7d / 111× 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 143 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-55717?
CVE-2026-55717 is a medium vulnerability published on July 22, 2026. In NLnet Labs Unbound 1.10.0 up to and including 1.25.1, when 'serve-expired: yes' is set together with a 'response-ip: <net> redirect' /'response-ip-data: <net> CNAME <target>' rule (or the RPZ 'rpz-cname-override' equivalent), a remote client who controls any delegated domain can crash the…
When was CVE-2026-55717 disclosed?
CVE-2026-55717 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-2026-55717 actively exploited?
CVE-2026-55717 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 85.4% of all scored CVEs.
What is the CVSS score of CVE-2026-55717?
CVE-2026-55717 has a CVSS v3 base score of 5.9 (NVD).
How do I remediate CVE-2026-55717?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-55717, 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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