CVE-2026-55973

HIGHPre-NVD 7.57.5
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

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, GitHub Security Advisory, a secondary CVSS source

Also known asEUVD-2026-47681 (ENISA EUVD) · GHSA-g479-fg97-pf5w (GitHub Security Advisories)Source: ENISA EUVD

7.5EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 7.5Exploit: None knownExposed services: Not assessed

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
7.5HIGHmedium confidence
EG Risk
49
EG Risk 49/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity75% × 45%
Impact severity (EG Severity): CVSS 7.5 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.3% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.3%
EPSS %ILE
20th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (7.5): severity, escalated by confirmed exploitation. This CVE's 7.5 is its impact severity (EG Severity), not escalated.

EG Severity
7.5 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.3% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-11). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; 60 days if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

July 22, 2026

Last Modified

October 24, 2026

Advisory Details (1)

Auto-updated Jul 22, 2026
Patch available.

Patch Availability(7)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntuunbound-host (1.9.4-2ubuntu1.11+esm3) @ focal2026-11-12ubuntu
ubuntuunbound-host (1.25.1-1ubuntu3.1) @ stonking2026-11-12ubuntu
redhatopenshift/ose-rhel-coreos-9:4.22.9.8.202609081748-02026-09-15redhat
redhatopenshift/ose-rhel-coreos-9:4.22.9.8.202608251819-02026-09-01redhat
redhatunbound-0:1.24.2-7.el10_2.42026-08-17redhat
redhatunbound-0:1.24.2-3.el9_8.42026-08-17redhat
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

(7 across 7 ecosystems)
Alpine:v3.22(1)
PackageVulnerable rangeFix by version rangeDependents
unbound—
  • 1.23.0 up to 1.25.2-r0: fixed in 1.25.2-r0
—
Alpine:v3.23(1)
PackageVulnerable rangeFix by version rangeDependents
unbound—
  • 1.23.0 up to 1.25.2-r0: fixed in 1.25.2-r0
—
Alpine:v3.24(1)
PackageVulnerable rangeFix by version rangeDependents
unbound—
  • 1.23.0 up to 1.25.2-r0: fixed in 1.25.2-r0
—
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
unbound1.13.1-1 ... 1.25.2-1 (47 versions)
  • every version on: no fix on record
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
unbound1.17.1-2 ... 1.26.2-1 (27 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
unbound1.22.0-2 ... 1.26.0-2 (15 versions)
  • every version up to 1.26.1-0+deb13u1: fixed in 1.26.1-0+deb13u1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
unbound1.22.0-2 ... 1.25.1-1 (9 versions)
  • every version up to 1.25.2-1: fixed in 1.25.2-1
—

Weakness Classification(1)

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

Additional Vendor Advisories

(2)

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 9× in last 7d / 42× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed its CVE.org record (CNA or CISA ADP). An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). "EchelonGraph re-scored" is our own recompute of this CVE's score, not an update from a source, and is not counted in the refreshes above. Most recent first.

Showing the most recent 100 of 372 rows on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 272 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-12 16:34 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  2. 2026-11-12 15:33 UTCEchelonGraph re-scored
  3. 2026-11-12 15:33 UTCVendor advisory
  4. 2026-11-12 15:33 UTCGHSA enrichmentGHSA-g479-fg97-pf5w · GitHub severity HIGH · GitHub CVSS 7.5
  5. 2026-11-11 16:40 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  6. 2026-11-10 16:44 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  7. 2026-11-09 16:35 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  8. 2026-11-08 16:40 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  9. 2026-11-07 16:39 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  10. 2026-11-06 16:38 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  11. 2026-11-06 06:56 UTCEchelonGraph re-scored
  12. 2026-11-06 06:56 UTCVendor advisory
  13. 2026-11-06 06:56 UTCGHSA enrichmentGHSA-g479-fg97-pf5w · GitHub severity HIGH · GitHub CVSS 7.5
  14. 2026-11-05 16:38 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  15. 2026-11-04 16:36 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  16. 2026-11-03 16:48 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  17. 2026-11-02 16:45 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  18. 2026-11-01 16:34 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  19. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  20. 2026-10-30 22:20 UTCEchelonGraph re-scored
  21. 2026-10-30 22:20 UTCVendor advisory
  22. 2026-10-30 22:20 UTCGHSA enrichmentGHSA-g479-fg97-pf5w · GitHub severity HIGH · GitHub CVSS 7.5
  23. 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  24. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  25. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.3% · 20th percentile
Show 75 more
  1. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  2. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  3. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  4. 2026-10-25 14:18 UTCEchelonGraph re-scored
  5. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  6. 2026-10-24 13:32 UTCEchelonGraph re-scored
  7. 2026-10-24 13:32 UTCVendor advisory
  8. 2026-10-24 13:32 UTCGHSA enrichmentGHSA-g479-fg97-pf5w · GitHub severity HIGH · GitHub CVSS 7.5
  9. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  10. 2026-10-23 11:52 UTCEchelonGraph re-scored
  11. 2026-10-23 11:52 UTCVendor advisory
  12. 2026-10-23 11:52 UTCGHSA enrichmentGHSA-g479-fg97-pf5w · GitHub severity HIGH · GitHub CVSS 7.5
  13. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  14. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  15. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  16. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  17. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  18. 2026-10-18 03:29 UTCEchelonGraph re-scored
  19. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  20. 2026-10-17 03:10 UTCEchelonGraph re-scored
  21. 2026-10-17 03:10 UTCVendor advisory
  22. 2026-10-17 03:10 UTCGHSA enrichmentGHSA-g479-fg97-pf5w · GitHub severity HIGH · GitHub CVSS 7.5
  23. 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  24. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  25. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  26. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  27. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  28. 2026-10-12 15:55 UTCEchelonGraph re-scored
  29. 2026-10-11 19:38 UTCEchelonGraph re-scored
  30. 2026-10-11 16:53 UTCEchelonGraph re-scored
  31. 2026-10-11 14:16 UTCEchelonGraph re-scored
  32. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  33. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  34. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  35. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  36. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  37. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  38. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  39. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  40. 2026-10-04 13:26 UTCEchelonGraph re-scored
  41. 2026-10-04 13:26 UTCVendor advisory
  42. 2026-10-04 13:26 UTCGHSA enrichmentGHSA-g479-fg97-pf5w · GitHub severity HIGH · GitHub CVSS 7.5
  43. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  44. 2026-10-03 03:34 UTCEchelonGraph re-scored
  45. 2026-10-03 03:34 UTCVendor advisory
  46. 2026-10-03 03:34 UTCGHSA enrichmentGHSA-g479-fg97-pf5w · GitHub severity HIGH · GitHub CVSS 7.5
  47. 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  48. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  49. 2026-10-01 06:29 UTCEchelonGraph re-scored
  50. 2026-10-01 06:29 UTCVendor advisory
  51. 2026-10-01 06:29 UTCGHSA enrichmentGHSA-g479-fg97-pf5w · GitHub severity HIGH · GitHub CVSS 7.5
  52. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  53. 2026-09-29 15:22 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  54. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  55. 2026-09-28 05:18 UTCEchelonGraph re-scored
  56. 2026-09-28 05:18 UTCVendor advisory
  57. 2026-09-28 05:18 UTCGHSA enrichmentGHSA-g479-fg97-pf5w · GitHub severity HIGH · GitHub CVSS 7.5
  58. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  59. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  60. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  61. 2026-09-24 11:01 UTCVendor advisory
  62. 2026-09-24 11:01 UTCGHSA enrichmentGHSA-g479-fg97-pf5w · GitHub severity HIGH · GitHub CVSS 7.5
  63. 2026-09-23 22:26 UTCEchelonGraph re-scored
  64. 2026-09-23 22:26 UTCVendor advisory
  65. 2026-09-23 22:26 UTCGHSA enrichmentGHSA-g479-fg97-pf5w · GitHub severity HIGH · GitHub CVSS 7.5
  66. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  67. 2026-09-22 23:59 UTCEchelonGraph re-scored
  68. 2026-09-22 23:59 UTCVendor advisory
  69. 2026-09-22 23:59 UTCGHSA enrichmentGHSA-g479-fg97-pf5w · GitHub severity HIGH · GitHub CVSS 7.5
  70. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  71. 2026-09-20 02:04 UTCEchelonGraph re-scored
  72. 2026-09-20 02:04 UTCVendor advisory
  73. 2026-09-20 02:04 UTCGHSA enrichmentGHSA-g479-fg97-pf5w · GitHub severity HIGH · GitHub CVSS 7.5
  74. 2026-09-18 22:41 UTCEchelonGraph re-scored
  75. 2026-09-18 22:41 UTCVendor advisory

Frequently asked(5)

What is CVE-2026-55973?
CVE-2026-55973 is a high-severity vulnerability; its CVE record was 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 made public?
CVE-2026-55973 was made public on July 22, 2026: that is the date its CVE record's CNA, NLnet Labs, gives for when the vulnerability was made public. The CVE record itself was published on July 22, 2026. EchelonGraph's copy of the record carries a last-modified date of October 24, 2026; the record at its source may have been updated since.
Is CVE-2026-55973 actively exploited?
CVE-2026-55973 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (20th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-55973?
CVE-2026-55973 has a CVSS base score of 7.5 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-55973?
A fix for CVE-2026-55973 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-55973 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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