CVE-2026-3593

CRITICALNVD 9.89.8
EchelonGraph scoreMEDIUM confidence

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

This critical-severity CVE scores 9.8 under NVD CVSS v3. EPSS exploit probability: 1.1% (64th percentile of EPSS-scored CVEs). GitHub Security Advisory CVSS 7.4 is lower than this score; a lower GitHub score revises it only when its advisory is newer than the CVE record's last change, and this advisory (published 2026-05-20) is not newer than that change (2026-09-01), so it does not.

Triggered by: Headline CVSS from NVD CVSS v3
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3
Trending — 4 sources updated this week
9.8EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1.1%CVSS: 9.8Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

A use-after-free vulnerability exists within the DNS-over-HTTPS implementation. This issue affects BIND 9 versions 9.20.0 through 9.20.22, 9.21.0 through 9.21.21, and 9.20.9-S1 through 9.20.22-S1. BIND 9 versions 9.18.0 through 9.18.48 and 9.18.11-S1 through 9.18.48-S1 are NOT affected.

CVSS v3
9.8
EG Score
9.8CRITICALmedium confidence
EG Risk
45
EG Risk 45/100

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)
Severity98% × 45%
Impact severity (EG Severity): CVSS 9.8 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation1.1% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at every mission impact level.
Exploitation none (CISA Vulnrichment) · Automatable no (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.
EPSS PROB
1.1%
EPSS %ILE
64th
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 (9.8): severity, escalated by confirmed exploitation. This CVE's 9.8 is its impact severity (EG Severity), not escalated.

EG Severity
9.8 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.NVD CVSS v3 · CVSS v3.0 or v3.1
EG Likelihood
1.1% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-19). 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 every mission impact level.CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (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)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable no (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

May 20, 2026

Last Modified

September 1, 2026

Advisory Details (7)

Auto-updated Oct 20, 2026
Patch available.
Web page

Index of /isc/bind9/9.21.22

https://downloads.isc.org/isc/bind9/9.21.22
Web page

Index of /isc/bind9/9.20.23

https://downloads.isc.org/isc/bind9/9.20.23
Web page

CVE-2026-3593: Heap use-after-free vulnerability in BIND 9 DNS-over-HTTPS implementation

https://kb.isc.org/docs/cve-2026-3593
Red HatMentions a patch (unverified)

Affected: Red Hat Enterprise Linux 10",

https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-3593.json
Red HatMentions a patch (unverified)

2479770 – (CVE-2026-3593) CVE-2026-3593 bind: Heap use-after-free vulnerability in BIND 9 DNS-over-HTTPS implementation

https://bugzilla.redhat.com/show_bug.cgi?id=2479770
Red HatMentions a patch (unverified)

CVE-2026-3593 - Red Hat Customer Portal

Affected: Red Hat Enterprise Linux 8 or OpenShift Container Platform 4, is affected by this vulnerability and a fix may be released to a

https://access.redhat.com/security/cve/CVE-2026-3593
Red HatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:7412

Patch Availability(2)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntubind9-utils (1:9.20.11-1ubuntu2.4) @ questing2026-10-18ubuntu
redhatbind-main-9.18.48-1.1.hum12026-04-10redhat

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:v3.20(1)
PackageVulnerable rangeFix by version rangeDependents
bind—
  • 9.20.0 up to 9.18.49-r0: fixed in 9.18.49-r0
—
Alpine:v3.21(1)
PackageVulnerable rangeFix by version rangeDependents
bind—
  • 9.20.0 up to 9.18.49-r0: fixed in 9.18.49-r0
—
Alpine:v3.22(1)
PackageVulnerable rangeFix by version rangeDependents
bind—
  • 9.20.0 up to 9.20.23-r0: fixed in 9.20.23-r0
—
Alpine:v3.23(1)
PackageVulnerable rangeFix by version rangeDependents
bind—
  • 9.20.0 up to 9.20.23-r0: fixed in 9.20.23-r0
—
Alpine:v3.24(1)
PackageVulnerable rangeFix by version rangeDependents
bind—
  • 9.20.0 up to 9.20.23-r0: fixed in 9.20.23-r0
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
bind91:9.20.11-4 ... 1:9.20.23-1~deb13u1~bpo12+1 (17 versions)
  • every version up to 1:9.20.23-1~deb13u1: fixed in 1:9.20.23-1~deb13u1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
bind91:9.20.11-4 ... 1:9.20.23-1~deb13u1~bpo12+1 (18 versions)
  • every version up to 1:9.20.23-1: fixed in 1:9.20.23-1
—

Weakness Classification(2)

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 26× in last 7d / 53× 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 it from the CNA feed. 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). Most recent first.

Showing the most recent 99 of 436 refreshes 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. 1 repeat row among the latest 100 is merged into the row it repeats. The 337 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-19 21:19 UTCEG score recompute
  2. 2026-10-19 21:19 UTCVendor advisory
  3. 2026-10-19 21:18 UTCGHSA enrichmentGHSA-8v2c-7qqj-7wp7 · GitHub severity HIGH · GitHub CVSS 7.4
  4. 2026-10-19 16:32 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  5. 2026-10-18 20:22 UTCEG score recompute
  6. 2026-10-18 20:22 UTCVendor advisory
  7. 2026-10-18 20:22 UTCGHSA enrichmentGHSA-8v2c-7qqj-7wp7 · GitHub severity HIGH · GitHub CVSS 7.4
  8. 2026-10-18 16:32 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  9. 2026-10-18 03:44 UTCEG score recompute
  10. 2026-10-17 19:44 UTCEG score recompute
  11. 2026-10-17 19:44 UTCVendor advisory
  12. 2026-10-17 19:44 UTCGHSA enrichmentGHSA-8v2c-7qqj-7wp7 · GitHub severity HIGH · GitHub CVSS 7.4
  13. 2026-10-17 16:34 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  14. 2026-10-16 19:06 UTCEG score recompute
  15. 2026-10-16 19:06 UTCVendor advisory
  16. 2026-10-16 19:05 UTCGHSA enrichmentGHSA-8v2c-7qqj-7wp7 · GitHub severity HIGH · GitHub CVSS 7.4
  17. 2026-10-16 16:42 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  18. 2026-10-15 16:32 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  19. 2026-10-15 16:18 UTCEG score recompute
  20. 2026-10-15 16:18 UTCVendor advisory
  21. 2026-10-15 16:17 UTCGHSA enrichmentGHSA-8v2c-7qqj-7wp7 · GitHub severity HIGH · GitHub CVSS 7.4
  22. 2026-10-14 16:32 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  23. 2026-10-14 10:22 UTCEG score recompute
  24. 2026-10-14 10:22 UTCVendor advisory
  25. 2026-10-14 10:21 UTCGHSA enrichmentGHSA-8v2c-7qqj-7wp7 · GitHub severity HIGH · GitHub CVSS 7.4
Show 74 more
  1. 2026-10-13 16:34 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  2. 2026-10-13 08:53 UTCEG score recompute
  3. 2026-10-13 08:53 UTCVendor advisory
  4. 2026-10-13 08:53 UTCGHSA enrichmentGHSA-8v2c-7qqj-7wp7 · GitHub severity HIGH · GitHub CVSS 7.4
  5. 2026-10-12 16:34 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  6. 2026-10-12 16:11 UTCEG score recompute
  7. 2026-10-12 08:15 UTCVendor advisory
  8. 2026-10-12 08:15 UTCGHSA enrichmentGHSA-8v2c-7qqj-7wp7 · GitHub severity HIGH · GitHub CVSS 7.4
  9. 2026-10-11 19:53 UTCEG score recompute
  10. 2026-10-11 17:06 UTCEG score recompute
  11. 2026-10-11 14:33 UTCEG score recompute
  12. 2026-10-11 13:48 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  13. 2026-10-10 20:00 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  14. 2026-10-10 00:55 UTCOSV refresh
  15. 2026-10-09 20:07 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  16. 2026-10-08 17:12 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  17. 2026-10-07 23:48 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  18. 2026-10-06 15:17 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  19. 2026-10-05 17:43 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  20. 2026-10-04 23:22 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  21. 2026-10-03 14:25 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  22. 2026-10-01 19:50 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  23. 2026-09-30 15:03 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  24. 2026-09-28 13:51 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  25. 2026-09-27 13:48 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  26. 2026-09-26 15:58 UTCEPSS rescoreEPSS 1.1% · 63rd percentile
  27. 2026-09-26 00:26 UTCEPSS rescoreEPSS 1.1% · 63rd percentile
  28. 2026-09-20 20:15 UTCEPSS rescoreEPSS 1.5% · 73rd percentile
  29. 2026-09-20 09:03 UTCOSV refresh
  30. 2026-09-18 19:28 UTCEPSS rescoreEPSS 1.5% · 73rd percentile
  31. 2026-09-17 19:30 UTCEPSS rescoreEPSS 1.5% · 73rd percentile
  32. 2026-09-16 14:08 UTCEPSS rescoreEPSS 1.5% · 73rd percentile
  33. 2026-09-16 05:15 UTCEPSS rescoreEPSS 1.5% · 73rd percentile
  34. 2026-09-15 03:11 UTCEPSS rescoreEPSS 1.5% · 73rd percentile
  35. 2026-09-13 16:47 UTCEPSS rescoreEPSS 1.5% · 73rd percentile
  36. 2026-09-12 15:01 UTCEPSS rescoreEPSS 1.5% · 73rd percentile
  37. 2026-09-11 14:53 UTCEPSS rescoreEPSS 1.5% · 73rd percentile
  38. 2026-09-11 09:37 UTCEPSS rescoreEPSS 1.5% · 73rd percentile
  39. 2026-09-10 09:34 UTCEPSS rescoreEPSS 1.5% · 73rd percentile
  40. 2026-09-08 22:00 UTCEPSS rescoreEPSS 1.5% · 73rd percentile
  41. 2026-09-07 16:01 UTCEPSS rescoreEPSS 1.5% · 73rd percentile
  42. 2026-09-06 13:47 UTCEPSS rescoreEPSS 1.5% · 73rd percentile
  43. 2026-09-04 05:06 UTCEPSS rescoreEPSS 1.5% · 73rd percentile
  44. 2026-09-02 14:12 UTCEPSS rescoreEPSS 1.5% · 73rd percentile
  45. 2026-09-01 13:53 UTCEPSS rescoreEPSS 1.5% · 73rd percentile
  46. 2026-09-01 12:21 UTCEG score recompute
  47. 2026-09-01 12:21 UTCVendor advisory
  48. 2026-09-01 12:21 UTCGHSA enrichmentGHSA-8v2c-7qqj-7wp7 · GitHub severity HIGH · GitHub CVSS 7.4
  49. 2026-09-01 04:39 UTCEPSS rescoreEPSS 1.5% · 73rd percentile
  50. 2026-08-30 19:17 UTCEPSS rescoreEPSS 1.5% · 73rd percentile
  51. 2026-08-30 01:22 UTCEPSS rescoreEPSS 1.5% · 72nd percentile
  52. 2026-08-28 21:41 UTCEPSS rescoreEPSS 1.5% · 72nd percentile
  53. 2026-08-27 14:25 UTCEPSS rescoreEPSS 1.5% · 73rd percentile
  54. 2026-08-26 14:46 UTCEPSS rescoreEPSS 1.5% · 73rd percentile
  55. 2026-08-25 13:49 UTCEPSS rescoreEPSS 1.5% · 72nd percentile
  56. 2026-08-24 13:29 UTCVendor advisory
  57. 2026-08-24 13:29 UTCGHSA enrichmentGHSA-8v2c-7qqj-7wp7 · GitHub severity HIGH · GitHub CVSS 7.4
  58. 2026-08-24 12:25 UTCEG score recompute
  59. 2026-08-24 12:25 UTCVendor advisory
  60. 2026-08-24 12:25 UTCGHSA enrichmentGHSA-8v2c-7qqj-7wp7 · GitHub severity HIGH · GitHub CVSS 7.4
  61. 2026-08-23 21:30 UTCVendor advisory
  62. 2026-08-23 21:30 UTCGHSA enrichmentGHSA-8v2c-7qqj-7wp7 · GitHub severity HIGH · GitHub CVSS 7.4
  63. 2026-08-23 16:55 UTCEG score recompute
  64. 2026-08-23 16:55 UTCVendor advisory
  65. 2026-08-23 16:55 UTCGHSA enrichmentGHSA-8v2c-7qqj-7wp7 · GitHub severity HIGH · GitHub CVSS 7.4
  66. 2026-08-23 00:19 UTCEPSS rescoreEPSS 1.5% · 72nd percentile
  67. 2026-08-21 23:49 UTCEPSS rescoreEPSS 1.5% · 72nd percentile
  68. 2026-08-21 22:55 UTCEG score recompute
  69. 2026-08-21 22:55 UTCVendor advisory
  70. 2026-08-21 22:55 UTCGHSA enrichmentGHSA-8v2c-7qqj-7wp7 · GitHub severity HIGH · GitHub CVSS 7.4
  71. 2026-08-20 22:55 UTCEPSS rescoreEPSS 1.5% · 72nd percentile
  72. 2026-08-20 18:55 UTCEG score recompute
  73. 2026-08-20 18:55 UTCVendor advisory
  74. 2026-08-20 18:55 UTCGHSA enrichmentGHSA-8v2c-7qqj-7wp7 · GitHub severity HIGH · GitHub CVSS 7.4

Frequently asked(5)

What is CVE-2026-3593?
CVE-2026-3593 is a critical-severity vulnerability; its CVE record was published on May 20, 2026. A use-after-free vulnerability exists within the DNS-over-HTTPS implementation. This issue affects BIND 9 versions 9.20.0 through 9.20.22, 9.21.0 through 9.21.21, and 9.20.9-S1 through 9.20.22-S1. BIND 9 versions 9.18.0 through 9.18.48 and 9.18.11-S1 through 9.18.48-S1 are NOT affected.
When was CVE-2026-3593 made public?
CVE-2026-3593 was made public on May 20, 2026: that is the date its CVE record's CNA, Internet Systems Consortium (ISC), gives for when the vulnerability was made public. The CVE record itself was published on May 20, 2026. EchelonGraph's copy of the record carries a last-modified date of September 1, 2026; the record at its source may have been updated since.
Is CVE-2026-3593 actively exploited?
CVE-2026-3593 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1.1% probability of exploitation in the next 30 days (64th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-3593?
CVE-2026-3593 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-3593?
A fix for CVE-2026-3593 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-3593 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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