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 ... 1.26.0-2 (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 / 96× 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 203 total refreshes for this CVE.

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

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 84.9% 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.

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