CVE-2026-4689

CRITICALNVD 10.010.0
EchelonGraph scoreMEDIUM confidence

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

Score 10.0 from GitHub Security Advisory (severity: CRITICAL) published 2026-03-24. NVD baseline CVSS 10.0; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3
Trending — 4 sources updated this week

Also known asEUVD-2026-14802 (ENISA EUVD) · GHSA-j5qx-hh9g-j6wj (GitHub Security Advisories)Source: ENISA EUVD

10.0EG
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: 0.7%CVSS: 10.0Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

Sandbox escape due to incorrect boundary conditions, integer overflow in the XPCOM component. This vulnerability was fixed in Firefox 149, Firefox ESR 115.34, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.

CVSS v3
10.0
EG Score
10.0CRITICALmedium 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)
Severity100% × 45%
Impact severity (EG Severity): CVSS 10.0 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.7% × 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
0.7%
EPSS %ILE
52nd
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 (10.0): severity, escalated by confirmed exploitation. This CVE's 10.0 is its impact severity (EG Severity), not escalated.

EG Severity
10.0 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.7% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-01). 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; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade 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; 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.

The score's inputs: 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

March 24, 2026

Last Modified

July 15, 2026

Advisory Details (10)

Auto-updated Oct 30, 2026
Patch available. Sources: redhat.
Red HatMentions a patch (unverified)

Affected: Red Hat Enterprise Linux 9.

https://access.redhat.com/errata/RHSA-2026:6188
Red HatMentions a patch (unverified)

Affected: Red Hat Enterprise Linux 8.

https://access.redhat.com/errata/RHSA-2026:5932
Red HatMentions a patch (unverified)

Affected: Red Hat Enterprise Linux 10.

https://access.redhat.com/errata/RHSA-2026:5931
Red HatMentions a patch (unverified)

Affected: Red Hat Enterprise Linux 9.

https://access.redhat.com/errata/RHSA-2026:5930
Web page

Security Vulnerabilities fixed in Thunderbird 140.9 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-24/
Web page

Security Vulnerabilities fixed in Thunderbird 149 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-23/
Web page

Security Vulnerabilities fixed in Firefox ESR 140.9 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-22/
Web page

Security Vulnerabilities fixed in Firefox ESR 115.34 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-21/
Web page

Security Vulnerabilities fixed in Firefox 149 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-20/
Web page

2016374 - (CVE-2026-4689) SlicedInputStream::Read uint64 Count Wrap Heap Buffer Overflow

https://bugzilla.mozilla.org/show_bug.cgi?id=2016374

Patch Availability(25)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatthunderbird-0:140.9.0-1.el8_42026-04-20redhat
redhatfirefox-0:140.9.0-1.el7_92026-04-16redhat
redhatthunderbird-0:140.9.0-1.el8_82026-04-15redhat
redhatthunderbird-0:140.9.0-1.el9_42026-04-15redhat
redhatthunderbird-0:140.9.0-1.el8_22026-04-15redhat
redhatthunderbird-0:140.9.0-1.el8_62026-04-15redhat
redhatthunderbird-0:140.9.0-1.el10_02026-04-15redhat
redhatthunderbird-0:140.9.0-1.el9_22026-04-15redhat
redhatthunderbird-0:140.9.0-1.el9_62026-04-15redhat
redhatthunderbird-0:140.9.0-1.el9_02026-04-15redhat
redhatfirefox-0:140.9.0-1.el10_02026-04-13redhat
redhatfirefox-0:140.9.0-1.el9_42026-04-13redhat
redhatfirefox-0:140.9.0-1.el8_42026-04-13redhat
redhatfirefox-0:140.9.0-1.el8_82026-04-13redhat
redhatfirefox-0:140.9.0-1.el8_22026-04-13redhat
redhatfirefox-0:140.9.0-1.el8_62026-04-13redhat
redhatfirefox-0:140.9.0-1.el9_02026-04-13redhat
redhatfirefox-0:140.9.0-1.el9_62026-04-13redhat
redhatfirefox-0:140.9.0-1.el9_22026-04-13redhat
redhatthunderbird-0:140.9.0-1.el8_102026-04-07redhat
redhatthunderbird-0:140.9.0-1.el10_12026-04-01redhat
redhatthunderbird-0:140.9.0-1.el9_72026-03-30redhat
redhatfirefox-0:140.9.0-1.el8_102026-03-26redhat
redhatfirefox-0:140.9.0-1.el9_72026-03-26redhat
redhatfirefox-0:140.9.0-1.el10_12026-03-26redhat

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.

Affected Packages

(8 across 4 ecosystems)
Debian:11(2)
PackageVulnerable rangeFix by version rangeDependents
firefox-esr102.1.0esr-1 ... 91.9.1esr-1~deb9u1 (255 versions)
  • every version up to 140.9.0esr-1~deb11u1: fixed in 140.9.0esr-1~deb11u1
—
thunderbird1:102.0.1-1 ... 1:91.9.0-1~deb9u1 (306 versions)
  • every version up to 1:140.9.0esr-1~deb11u1: fixed in 1:140.9.0esr-1~deb11u1
—
Debian:12(2)
PackageVulnerable rangeFix by version rangeDependents
firefox-esr102.11.0esr-1 ... 140.8.0esr-1~deb13u1 (161 versions)
  • every version up to 140.9.0esr-1~deb12u1: fixed in 140.9.0esr-1~deb12u1
—
thunderbird1:102.11.0-1 ... 1:140.9.0esr-1~deb11u1 (191 versions)
  • every version up to 1:140.9.0esr-1~deb12u1: fixed in 1:140.9.0esr-1~deb12u1
—
Debian:13(2)
PackageVulnerable rangeFix by version rangeDependents
firefox-esr128.13.0esr-1 ... 140.8.0esr-1~deb13u1 (36 versions)
  • every version up to 140.9.0esr-1~deb13u1: fixed in 140.9.0esr-1~deb13u1
—
thunderbird1:128.13.0esr-1 ... 1:140.9.0esr-1~deb11u1 (46 versions)
  • every version up to 1:140.9.0esr-1~deb13u1: fixed in 1:140.9.0esr-1~deb13u1
—
Debian:14(2)
PackageVulnerable rangeFix by version rangeDependents
firefox-esr128.13.0esr-1 ... 140.9.0esr-1~deb13u1 (39 versions)
  • every version up to 140.9.0esr-1: fixed in 140.9.0esr-1
—
thunderbird1:128.13.0esr-1 ... 1:140.9.0esr-1~deb13u1 (48 versions)
  • every version up to 1:140.9.0esr-1: fixed in 1:140.9.0esr-1
—

Weakness Classification(3)

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

Additional Vendor Advisories

(5)

Data Freshness Timeline

(refreshed 28× in last 7d / 100× 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 367 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 267 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-02 02:22 UTCEG score recompute
  2. 2026-11-02 02:22 UTCVendor advisory
  3. 2026-11-02 02:22 UTCGHSA enrichmentGHSA-j5qx-hh9g-j6wj · GitHub severity CRITICAL · GitHub CVSS 10.0
  4. 2026-11-01 16:34 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  5. 2026-11-01 03:21 UTCEG score recompute
  6. 2026-11-01 03:21 UTCVendor advisory
  7. 2026-11-01 03:21 UTCGHSA enrichmentGHSA-j5qx-hh9g-j6wj · GitHub severity CRITICAL · GitHub CVSS 10.0
  8. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  9. 2026-10-31 04:20 UTCEG score recompute
  10. 2026-10-31 04:20 UTCVendor advisory
  11. 2026-10-31 04:20 UTCGHSA enrichmentGHSA-j5qx-hh9g-j6wj · GitHub severity CRITICAL · GitHub CVSS 10.0
  12. 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  13. 2026-10-30 05:15 UTCEG score recompute
  14. 2026-10-30 05:15 UTCVendor advisory
  15. 2026-10-30 05:15 UTCGHSA enrichmentGHSA-j5qx-hh9g-j6wj · GitHub severity CRITICAL · GitHub CVSS 10.0
  16. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  17. 2026-10-29 06:14 UTCEG score recompute
  18. 2026-10-29 06:14 UTCVendor advisory
  19. 2026-10-29 06:14 UTCGHSA enrichmentGHSA-j5qx-hh9g-j6wj · GitHub severity CRITICAL · GitHub CVSS 10.0
  20. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  21. 2026-10-28 07:13 UTCEG score recompute
  22. 2026-10-28 07:13 UTCVendor advisory
  23. 2026-10-28 07:13 UTCGHSA enrichmentGHSA-j5qx-hh9g-j6wj · GitHub severity CRITICAL · GitHub CVSS 10.0
  24. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  25. 2026-10-27 08:12 UTCEG score recompute
Show 75 more
  1. 2026-10-27 08:12 UTCVendor advisory
  2. 2026-10-27 08:11 UTCGHSA enrichmentGHSA-j5qx-hh9g-j6wj · GitHub severity CRITICAL · GitHub CVSS 10.0
  3. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  4. 2026-10-26 06:54 UTCEG score recompute
  5. 2026-10-26 06:54 UTCVendor advisory
  6. 2026-10-26 06:54 UTCGHSA enrichmentGHSA-j5qx-hh9g-j6wj · GitHub severity CRITICAL · GitHub CVSS 10.0
  7. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  8. 2026-10-25 14:24 UTCEG score recompute
  9. 2026-10-25 07:52 UTCEG score recompute
  10. 2026-10-25 07:52 UTCVendor advisory
  11. 2026-10-25 07:52 UTCGHSA enrichmentGHSA-j5qx-hh9g-j6wj · GitHub severity CRITICAL · GitHub CVSS 10.0
  12. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  13. 2026-10-24 08:50 UTCEG score recompute
  14. 2026-10-24 08:50 UTCVendor advisory
  15. 2026-10-24 08:50 UTCGHSA enrichmentGHSA-j5qx-hh9g-j6wj · GitHub severity CRITICAL · GitHub CVSS 10.0
  16. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  17. 2026-10-23 09:48 UTCEG score recompute
  18. 2026-10-23 09:48 UTCVendor advisory
  19. 2026-10-23 09:48 UTCGHSA enrichmentGHSA-j5qx-hh9g-j6wj · GitHub severity CRITICAL · GitHub CVSS 10.0
  20. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  21. 2026-10-22 10:43 UTCEG score recompute
  22. 2026-10-22 10:43 UTCVendor advisory
  23. 2026-10-22 10:42 UTCGHSA enrichmentGHSA-j5qx-hh9g-j6wj · GitHub severity CRITICAL · GitHub CVSS 10.0
  24. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  25. 2026-10-21 11:38 UTCEG score recompute
  26. 2026-10-21 11:38 UTCVendor advisory
  27. 2026-10-21 11:38 UTCGHSA enrichmentGHSA-j5qx-hh9g-j6wj · GitHub severity CRITICAL · GitHub CVSS 10.0
  28. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  29. 2026-10-20 12:37 UTCEG score recompute
  30. 2026-10-20 12:37 UTCVendor advisory
  31. 2026-10-20 12:36 UTCGHSA enrichmentGHSA-j5qx-hh9g-j6wj · GitHub severity CRITICAL · GitHub CVSS 10.0
  32. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  33. 2026-10-19 13:19 UTCEG score recompute
  34. 2026-10-19 13:19 UTCVendor advisory
  35. 2026-10-19 13:19 UTCGHSA enrichmentGHSA-j5qx-hh9g-j6wj · GitHub severity CRITICAL · GitHub CVSS 10.0
  36. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  37. 2026-10-18 12:36 UTCVendor advisory
  38. 2026-10-18 12:36 UTCGHSA enrichmentGHSA-j5qx-hh9g-j6wj · GitHub severity CRITICAL · GitHub CVSS 10.0
  39. 2026-10-18 03:36 UTCEG score recompute
  40. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  41. 2026-10-17 13:32 UTCEG score recompute
  42. 2026-10-17 13:32 UTCVendor advisory
  43. 2026-10-17 13:32 UTCGHSA enrichmentGHSA-j5qx-hh9g-j6wj · GitHub severity CRITICAL · GitHub CVSS 10.0
  44. 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  45. 2026-10-16 14:28 UTCEG score recompute
  46. 2026-10-16 14:28 UTCVendor advisory
  47. 2026-10-16 14:28 UTCGHSA enrichmentGHSA-j5qx-hh9g-j6wj · GitHub severity CRITICAL · GitHub CVSS 10.0
  48. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  49. 2026-10-15 14:52 UTCEG score recompute
  50. 2026-10-15 14:52 UTCVendor advisory
  51. 2026-10-15 14:51 UTCGHSA enrichmentGHSA-j5qx-hh9g-j6wj · GitHub severity CRITICAL · GitHub CVSS 10.0
  52. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  53. 2026-10-14 09:20 UTCEG score recompute
  54. 2026-10-14 09:20 UTCVendor advisory
  55. 2026-10-14 09:20 UTCGHSA enrichmentGHSA-j5qx-hh9g-j6wj · GitHub severity CRITICAL · GitHub CVSS 10.0
  56. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  57. 2026-10-13 06:41 UTCEG score recompute
  58. 2026-10-13 06:41 UTCVendor advisory
  59. 2026-10-13 06:41 UTCGHSA enrichmentGHSA-j5qx-hh9g-j6wj · GitHub severity CRITICAL · GitHub CVSS 10.0
  60. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  61. 2026-10-12 16:02 UTCEG score recompute
  62. 2026-10-12 07:37 UTCVendor advisory
  63. 2026-10-12 07:37 UTCGHSA enrichmentGHSA-j5qx-hh9g-j6wj · GitHub severity CRITICAL · GitHub CVSS 10.0
  64. 2026-10-11 19:45 UTCEG score recompute
  65. 2026-10-11 16:59 UTCEG score recompute
  66. 2026-10-11 14:24 UTCEG score recompute
  67. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  68. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  69. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  70. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  71. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  72. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  73. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  74. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  75. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.7% · 50th percentile

Frequently asked(5)

What is CVE-2026-4689?
CVE-2026-4689 is a critical-severity vulnerability; its CVE record was published on March 24, 2026. Sandbox escape due to incorrect boundary conditions, integer overflow in the XPCOM component. This vulnerability was fixed in Firefox 149, Firefox ESR 115.34, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.
When was the CVE record for CVE-2026-4689 published?
The CVE record for CVE-2026-4689 was published on March 24, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of July 15, 2026; the record at its source may have been updated since.
Is CVE-2026-4689 actively exploited?
CVE-2026-4689 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.7% probability of exploitation in the next 30 days (52nd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-4689?
CVE-2026-4689 has a CVSS v3 base score of 10.0 (NVD).
How do I remediate CVE-2026-4689?
A fix for CVE-2026-4689 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-4689 are linked in the Vendor Advisories panel on this page.

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