CVE-2026-66798

MEDIUMPre-NVD 4.34.3
EchelonGraph scoreMEDIUM confidence

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

Score 4.3 from GitHub Security Advisory published 2026-08-28. The CNA's CVSS baseline 4.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: the CNA's CVSS, EPSS, GitHub Security Advisory
Trending — 4 sources updated this week
4.3EG
EchelonGraph verdictMonitorRemediate within your standard update timelines (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.8%CVSS: 4.3Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

Use after free in Microsoft Edge (Chromium-based) allows an unauthorized attacker to execute code over a network.

CVSS v3
4.3
EG Score
4.3MEDIUMmedium confidence
EG Risk
20
EG Risk 20/100

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 (value × EchelonGraph’s weight)
Severity43% × 45%
The EG Score, 4.3 of 10.
Exploitation0.8% × 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 low or medium mission impact; Track* at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (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
0.8%
EPSS %ILE
55th
KEV
Not listed

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

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

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (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; Fix on system upgrade if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact total (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

August 28, 2026

Last Modified

October 8, 2026

Advisory Details (1)

Auto-updated Aug 28, 2026
Patch available. Sources: microsoft.
MicrosoftMentions a patch (unverified)

Security Update Guide - Microsoft Security Response Center

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66798

Vendor Advisories for CVE-2026-66798(8)

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

Patch Availability(6)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatrhacm2/cluster-backup-rhel9-operator:17876846682026-08-26redhat
redhatrhacm2/cluster-backup-rhel9-operator:17872590602026-08-26redhat
redhatrhacm2/cluster-backup-rhel9-operator:17871831782026-08-26redhat
redhatrhacm2/cluster-backup-rhel9-operator:17872385002026-08-26redhat
redhatrhacm2/cluster-backup-rhel9-operator:17871831762026-08-26redhat
redhatrhacm2/cluster-backup-rhel9-operator:17872275762026-08-26redhat

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.

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 21× in last 7d / 104× 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 100 of 203 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. None are among the latest 100 rows. The 103 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  2. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  3. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  4. 2026-10-12 15:46 UTCEG score recompute
  5. 2026-10-11 19:31 UTCEG score recompute
  6. 2026-10-11 16:46 UTCEG score recompute
  7. 2026-10-11 14:07 UTCEG score recompute
  8. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  9. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  10. 2026-10-10 00:50 UTCEG score recompute
  11. 2026-10-10 00:50 UTCVendor advisory
  12. 2026-10-10 00:50 UTCGHSA enrichmentGHSA-c27v-65fh-7pg2 · GitHub CVSS 4.3
  13. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  14. 2026-10-08 19:07 UTCEG score recompute
  15. 2026-10-08 19:07 UTCVendor advisory
  16. 2026-10-08 19:07 UTCGHSA enrichmentGHSA-c27v-65fh-7pg2 · GitHub CVSS 4.3
  17. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  18. 2026-10-08 03:02 UTCEG score recompute
  19. 2026-10-08 03:02 UTCVendor advisory
  20. 2026-10-08 03:02 UTCGHSA enrichmentGHSA-c27v-65fh-7pg2 · GitHub CVSS 4.3
  21. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  22. 2026-10-07 02:44 UTCEG score recompute
  23. 2026-10-07 02:44 UTCVendor advisory
  24. 2026-10-07 02:44 UTCGHSA enrichmentGHSA-c27v-65fh-7pg2 · GitHub CVSS 4.3
  25. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.8% · 54th percentile
Show 75 more
  1. 2026-10-06 02:32 UTCEG score recompute
  2. 2026-10-06 02:32 UTCVendor advisory
  3. 2026-10-06 02:32 UTCGHSA enrichmentGHSA-c27v-65fh-7pg2 · GitHub CVSS 4.3
  4. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  5. 2026-10-05 02:20 UTCVendor advisory
  6. 2026-10-05 02:20 UTCGHSA enrichmentGHSA-c27v-65fh-7pg2 · GitHub CVSS 4.3
  7. 2026-10-04 01:54 UTCEG score recompute
  8. 2026-10-04 01:54 UTCVendor advisory
  9. 2026-10-04 01:54 UTCGHSA enrichmentGHSA-c27v-65fh-7pg2 · GitHub CVSS 4.3
  10. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  11. 2026-10-03 01:32 UTCEG score recompute
  12. 2026-10-03 01:32 UTCVendor advisory
  13. 2026-10-03 01:32 UTCGHSA enrichmentGHSA-c27v-65fh-7pg2 · GitHub CVSS 4.3
  14. 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  15. 2026-10-02 01:13 UTCEG score recompute
  16. 2026-10-02 01:13 UTCVendor advisory
  17. 2026-10-02 01:13 UTCGHSA enrichmentGHSA-c27v-65fh-7pg2 · GitHub CVSS 4.3
  18. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  19. 2026-10-01 00:59 UTCEG score recompute
  20. 2026-10-01 00:59 UTCVendor advisory
  21. 2026-10-01 00:59 UTCGHSA enrichmentGHSA-c27v-65fh-7pg2 · GitHub CVSS 4.3
  22. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  23. 2026-09-29 23:37 UTCEG score recompute
  24. 2026-09-29 23:37 UTCVendor advisory
  25. 2026-09-29 23:37 UTCGHSA enrichmentGHSA-c27v-65fh-7pg2 · GitHub CVSS 4.3
  26. 2026-09-28 21:08 UTCEG score recompute
  27. 2026-09-28 21:08 UTCVendor advisory
  28. 2026-09-28 21:08 UTCGHSA enrichmentGHSA-c27v-65fh-7pg2 · GitHub CVSS 4.3
  29. 2026-09-28 13:52 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  30. 2026-09-27 20:36 UTCEG score recompute
  31. 2026-09-27 20:36 UTCVendor advisory
  32. 2026-09-27 20:36 UTCGHSA enrichmentGHSA-c27v-65fh-7pg2 · GitHub CVSS 4.3
  33. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  34. 2026-09-26 20:24 UTCEG score recompute
  35. 2026-09-26 20:24 UTCVendor advisory
  36. 2026-09-26 20:24 UTCGHSA enrichmentGHSA-c27v-65fh-7pg2 · GitHub CVSS 4.3
  37. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  38. 2026-09-25 19:47 UTCVendor advisory
  39. 2026-09-25 19:46 UTCGHSA enrichmentGHSA-c27v-65fh-7pg2 · GitHub CVSS 4.3
  40. 2026-09-25 14:12 UTCEG score recompute
  41. 2026-09-25 14:12 UTCVendor advisory
  42. 2026-09-25 14:12 UTCGHSA enrichmentGHSA-c27v-65fh-7pg2 · GitHub CVSS 4.3
  43. 2026-09-24 13:54 UTCVendor advisory
  44. 2026-09-24 13:54 UTCGHSA enrichmentGHSA-c27v-65fh-7pg2 · GitHub CVSS 4.3
  45. 2026-09-23 22:29 UTCEG score recompute
  46. 2026-09-23 22:29 UTCVendor advisory
  47. 2026-09-23 22:29 UTCGHSA enrichmentGHSA-c27v-65fh-7pg2 · GitHub CVSS 4.3
  48. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  49. 2026-09-22 22:17 UTCEG score recompute
  50. 2026-09-22 22:17 UTCVendor advisory
  51. 2026-09-22 22:17 UTCGHSA enrichmentGHSA-c27v-65fh-7pg2 · GitHub CVSS 4.3
  52. 2026-09-21 22:04 UTCEG score recompute
  53. 2026-09-21 22:04 UTCVendor advisory
  54. 2026-09-21 22:04 UTCGHSA enrichmentGHSA-c27v-65fh-7pg2 · GitHub CVSS 4.3
  55. 2026-09-20 21:53 UTCEG score recompute
  56. 2026-09-20 21:53 UTCVendor advisory
  57. 2026-09-20 21:53 UTCGHSA enrichmentGHSA-c27v-65fh-7pg2 · GitHub CVSS 4.3
  58. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  59. 2026-09-19 21:40 UTCEG score recompute
  60. 2026-09-19 21:40 UTCVendor advisory
  61. 2026-09-19 21:40 UTCGHSA enrichmentGHSA-c27v-65fh-7pg2 · GitHub CVSS 4.3
  62. 2026-09-18 21:28 UTCEG score recompute
  63. 2026-09-18 21:28 UTCVendor advisory
  64. 2026-09-18 21:28 UTCGHSA enrichmentGHSA-c27v-65fh-7pg2 · GitHub CVSS 4.3
  65. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  66. 2026-09-17 20:50 UTCEG score recompute
  67. 2026-09-17 20:50 UTCVendor advisory
  68. 2026-09-17 20:50 UTCGHSA enrichmentGHSA-c27v-65fh-7pg2 · GitHub CVSS 4.3
  69. 2026-09-16 16:56 UTCEG score recompute
  70. 2026-09-16 16:56 UTCVendor advisory
  71. 2026-09-16 16:56 UTCGHSA enrichmentGHSA-c27v-65fh-7pg2 · GitHub CVSS 4.3
  72. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.6% · 44th percentile
  73. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.6% · 44th percentile
  74. 2026-09-15 18:28 UTCEG score recompute
  75. 2026-09-15 18:28 UTCVendor advisory

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-66798?
CVE-2026-66798 is a medium-severity vulnerability; its CVE record was published on August 28, 2026. Use after free in Microsoft Edge (Chromium-based) allows an unauthorized attacker to execute code over a network.
When was CVE-2026-66798 made public?
CVE-2026-66798 was made public on August 28, 2026: that is the date its CVE record's CNA, Microsoft Corporation, gives for when the vulnerability was made public. The CVE record itself was published on August 28, 2026. EchelonGraph's copy of the record carries a last-modified date of October 8, 2026; the record at its source may have been updated since.
Is CVE-2026-66798 actively exploited?
CVE-2026-66798 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.8% probability of exploitation in the next 30 days (55th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-66798?
CVE-2026-66798 has a CVSS base score of 4.3 (the CNA's own assessment, by microsoft; NVD's own analysis pending).
How do I remediate CVE-2026-66798?
A fix for CVE-2026-66798 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-66798 are linked in the Vendor Advisories panel on this page.

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