CVE-2024-7521

CRITICALNVD 8.89.8
EchelonGraph scoreMEDIUM confidence

“▲” beside the score: it is higher than NVD's CVSS score.

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2024-08-06. NVD baseline CVSS 8.8; sources differ by 1.0.

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

Also known asEUVD-2024-48428 (ENISA EUVD) · GHSA-563c-g7mm-g4xp (GitHub Security Advisories)Source: ENISA EUVD

9.8EG
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: 0.6%CVSS: 8.8Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

Incomplete WebAssembly exception handing could have led to a use-after-free. This vulnerability affects Firefox < 129, Firefox ESR < 115.14, Firefox ESR < 128.1, Thunderbird < 128.1, and Thunderbird < 115.14.

CVSS v3
8.8
EG Score
9.8CRITICALmedium confidence
EG Risk
59
EG Risk 59/100

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.
Exploitation0.6% × 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 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 at low or medium mission impact and sooner than that at high.
EPSS PROB
0.6%
EPSS %ILE
49th
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.GitHub Security Advisory CVSS
EG Likelihood
0.6% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-31). 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: 3 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 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)3 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 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 6, 2024

Last Modified

August 12, 2024

Advisory Details (6)

Auto-updated Aug 2, 2026
Patch available.
Web page

Security Vulnerabilities fixed in Thunderbird 115.14 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2024-38/
Web page

Security Vulnerabilities fixed in Thunderbird 128.1 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2024-37/
Web page

Security Vulnerabilities fixed in Firefox ESR 128.1 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2024-35/
Web page

Security Vulnerabilities fixed in Firefox ESR 115.14 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2024-34/
Web page

Security Vulnerabilities fixed in Firefox 129 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2024-33/
Web page

1904644 - (CVE-2024-7521) Assertion failure: iter->done(), at js/src/jit/JitFrames.cpp:695

https://bugzilla.mozilla.org/show_bug.cgi?id=1904644

Vendor Advisories for CVE-2024-7521(1)

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

Patch Availability(19)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntufirefox-mozsymbols (129.0.1+build1-0ubuntu0.20.04.1) @ focal2026-11-01ubuntu
ubuntuxul-ext-lightning (1:115.15.0+build1-0ubuntu0.22.04.1) @ jammy2026-11-01ubuntu
redhatthunderbird-0:115.14.0-1.el8_42024-08-19redhat
redhatthunderbird-0:115.14.0-1.el8_62024-08-19redhat
redhatfirefox-0:115.14.0-2.el9_42024-08-15redhat
redhatthunderbird-0:115.14.0-1.el8_82024-08-14redhat
redhatthunderbird-0:115.14.0-1.el9_42024-08-14redhat
redhatthunderbird-0:115.14.0-1.el9_02024-08-14redhat
redhatthunderbird-0:115.14.0-1.el9_22024-08-14redhat
redhatthunderbird-0:115.14.0-1.el8_22024-08-14redhat
redhatfirefox-0:115.14.0-2.el8_102024-08-14redhat
redhatthunderbird-0:115.14.0-1.el8_102024-08-14redhat
redhatfirefox-0:115.14.0-2.el8_82024-08-13redhat
redhatfirefox-0:115.14.0-2.el7_92024-08-13redhat
redhatfirefox-0:115.14.0-2.el8_22024-08-13redhat
redhatfirefox-0:115.14.0-2.el9_22024-08-13redhat
redhatfirefox-0:115.14.0-2.el8_42024-08-13redhat
redhatfirefox-0:115.14.0-2.el8_62024-08-13redhat
redhatfirefox-0:115.14.0-2.el9_02024-08-13redhat

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 (166 versions)
  • every version up to 115.14.0esr-1~deb11u1: fixed in 115.14.0esr-1~deb11u1
—
thunderbird1:102.0.1-1 ... 1:91.9.0-1~deb9u1 (201 versions)
  • every version up to 1:115.14.0-1~deb11u1: fixed in 1:115.14.0-1~deb11u1
—
Debian:12(2)
PackageVulnerable rangeFix by version rangeDependents
firefox-esr102.11.0esr-1 ... 115.9.1esr-1~deb12u1 (73 versions)
  • every version up to 115.14.0esr-1~deb12u1: fixed in 115.14.0esr-1~deb12u1
—
thunderbird1:102.11.0-1 ... 1:115.9.0-1~deb12u1 (86 versions)
  • every version up to 1:115.14.0-1~deb12u1: fixed in 1:115.14.0-1~deb12u1
—
Debian:13(2)
PackageVulnerable rangeFix by version rangeDependents
firefox-esr—
  • every version up to 115.14.0esr-1: fixed in 115.14.0esr-1
—
thunderbird—
  • every version up to 1:128.1.0esr-1: fixed in 1:128.1.0esr-1
—
Debian:14(2)
PackageVulnerable rangeFix by version rangeDependents
firefox-esr—
  • every version up to 115.14.0esr-1: fixed in 115.14.0esr-1
—
thunderbird—
  • every version up to 1:128.1.0esr-1: fixed in 1:128.1.0esr-1
—

Weakness Classification(1)

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

All Vendor Advisories

(19)

Data Freshness Timeline

(refreshed 27× in last 7d / 95× 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 271 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 171 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-01 16:32 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  2. 2026-11-01 16:23 UTCVendor advisory
  3. 2026-11-01 16:23 UTCGHSA enrichmentGHSA-563c-g7mm-g4xp · GitHub severity CRITICAL · GitHub CVSS 9.8
  4. 2026-10-31 17:02 UTCEG score recompute
  5. 2026-10-31 17:02 UTCVendor advisory
  6. 2026-10-31 17:02 UTCGHSA enrichmentGHSA-563c-g7mm-g4xp · GitHub severity CRITICAL · GitHub CVSS 9.8
  7. 2026-10-31 16:30 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  8. 2026-10-30 17:38 UTCEG score recompute
  9. 2026-10-30 17:38 UTCVendor advisory
  10. 2026-10-30 17:38 UTCGHSA enrichmentGHSA-563c-g7mm-g4xp · GitHub severity CRITICAL · GitHub CVSS 9.8
  11. 2026-10-30 16:32 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  12. 2026-10-29 18:20 UTCEG score recompute
  13. 2026-10-29 18:20 UTCVendor advisory
  14. 2026-10-29 18:20 UTCGHSA enrichmentGHSA-563c-g7mm-g4xp · GitHub severity CRITICAL · GitHub CVSS 9.8
  15. 2026-10-29 16:31 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  16. 2026-10-28 19:02 UTCEG score recompute
  17. 2026-10-28 19:02 UTCVendor advisory
  18. 2026-10-28 19:02 UTCGHSA enrichmentGHSA-563c-g7mm-g4xp · GitHub severity CRITICAL · GitHub CVSS 9.8
  19. 2026-10-28 16:30 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  20. 2026-10-27 19:11 UTCEG score recompute
  21. 2026-10-27 19:11 UTCVendor advisory
  22. 2026-10-27 19:11 UTCGHSA enrichmentGHSA-563c-g7mm-g4xp · GitHub severity CRITICAL · GitHub CVSS 9.8
  23. 2026-10-27 16:30 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  24. 2026-10-26 19:53 UTCEG score recompute
  25. 2026-10-26 19:53 UTCVendor advisory
Show 75 more
  1. 2026-10-26 19:53 UTCGHSA enrichmentGHSA-563c-g7mm-g4xp · GitHub severity CRITICAL · GitHub CVSS 9.8
  2. 2026-10-26 16:29 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  3. 2026-10-25 18:17 UTCVendor advisory
  4. 2026-10-25 18:17 UTCGHSA enrichmentGHSA-563c-g7mm-g4xp · GitHub severity CRITICAL · GitHub CVSS 9.8
  5. 2026-10-25 16:52 UTCEG score recompute
  6. 2026-10-25 16:30 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  7. 2026-10-24 18:54 UTCEG score recompute
  8. 2026-10-24 18:54 UTCVendor advisory
  9. 2026-10-24 18:54 UTCGHSA enrichmentGHSA-563c-g7mm-g4xp · GitHub severity CRITICAL · GitHub CVSS 9.8
  10. 2026-10-24 16:30 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  11. 2026-10-23 19:36 UTCEG score recompute
  12. 2026-10-23 19:36 UTCVendor advisory
  13. 2026-10-23 19:36 UTCGHSA enrichmentGHSA-563c-g7mm-g4xp · GitHub severity CRITICAL · GitHub CVSS 9.8
  14. 2026-10-23 16:30 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  15. 2026-10-22 20:10 UTCEG score recompute
  16. 2026-10-22 20:10 UTCVendor advisory
  17. 2026-10-22 20:10 UTCGHSA enrichmentGHSA-563c-g7mm-g4xp · GitHub severity CRITICAL · GitHub CVSS 9.8
  18. 2026-10-22 16:32 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  19. 2026-10-21 20:49 UTCEG score recompute
  20. 2026-10-21 20:49 UTCVendor advisory
  21. 2026-10-21 20:49 UTCGHSA enrichmentGHSA-563c-g7mm-g4xp · GitHub severity CRITICAL · GitHub CVSS 9.8
  22. 2026-10-21 16:30 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  23. 2026-10-20 21:28 UTCEG score recompute
  24. 2026-10-20 21:28 UTCVendor advisory
  25. 2026-10-20 21:28 UTCGHSA enrichmentGHSA-563c-g7mm-g4xp · GitHub severity CRITICAL · GitHub CVSS 9.8
  26. 2026-10-20 16:31 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  27. 2026-10-19 22:09 UTCEG score recompute
  28. 2026-10-19 22:09 UTCVendor advisory
  29. 2026-10-19 22:09 UTCGHSA enrichmentGHSA-563c-g7mm-g4xp · GitHub severity CRITICAL · GitHub CVSS 9.8
  30. 2026-10-19 16:30 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  31. 2026-10-18 20:57 UTCEG score recompute
  32. 2026-10-18 20:57 UTCVendor advisory
  33. 2026-10-18 20:56 UTCGHSA enrichmentGHSA-563c-g7mm-g4xp · GitHub severity CRITICAL · GitHub CVSS 9.8
  34. 2026-10-18 16:30 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  35. 2026-10-18 05:56 UTCEG score recompute
  36. 2026-10-17 21:27 UTCEG score recompute
  37. 2026-10-17 21:27 UTCVendor advisory
  38. 2026-10-17 21:27 UTCGHSA enrichmentGHSA-563c-g7mm-g4xp · GitHub severity CRITICAL · GitHub CVSS 9.8
  39. 2026-10-17 16:32 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  40. 2026-10-16 22:09 UTCEG score recompute
  41. 2026-10-16 22:09 UTCVendor advisory
  42. 2026-10-16 22:08 UTCGHSA enrichmentGHSA-563c-g7mm-g4xp · GitHub severity CRITICAL · GitHub CVSS 9.8
  43. 2026-10-16 16:37 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  44. 2026-10-15 18:41 UTCEG score recompute
  45. 2026-10-15 18:41 UTCVendor advisory
  46. 2026-10-15 18:41 UTCGHSA enrichmentGHSA-563c-g7mm-g4xp · GitHub severity CRITICAL · GitHub CVSS 9.8
  47. 2026-10-15 16:30 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  48. 2026-10-14 16:30 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  49. 2026-10-14 12:21 UTCEG score recompute
  50. 2026-10-14 12:21 UTCVendor advisory
  51. 2026-10-14 12:21 UTCGHSA enrichmentGHSA-563c-g7mm-g4xp · GitHub severity CRITICAL · GitHub CVSS 9.8
  52. 2026-10-13 16:31 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  53. 2026-10-13 12:11 UTCVendor advisory
  54. 2026-10-13 12:11 UTCGHSA enrichmentGHSA-563c-g7mm-g4xp · GitHub severity CRITICAL · GitHub CVSS 9.8
  55. 2026-10-12 17:34 UTCEG score recompute
  56. 2026-10-12 16:32 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  57. 2026-10-12 12:51 UTCVendor advisory
  58. 2026-10-12 12:50 UTCGHSA enrichmentGHSA-563c-g7mm-g4xp · GitHub severity CRITICAL · GitHub CVSS 9.8
  59. 2026-10-11 21:00 UTCEG score recompute
  60. 2026-10-11 15:52 UTCEG score recompute
  61. 2026-10-11 13:46 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  62. 2026-10-10 19:58 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  63. 2026-10-10 03:25 UTCOSV refresh
  64. 2026-10-09 20:06 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  65. 2026-10-08 17:08 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  66. 2026-10-07 23:46 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  67. 2026-10-06 15:16 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  68. 2026-10-05 17:41 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  69. 2026-10-04 23:21 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  70. 2026-10-03 14:24 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  71. 2026-10-02 16:29 UTCEG score recompute
  72. 2026-10-01 19:48 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  73. 2026-09-30 15:02 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  74. 2026-09-29 15:18 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  75. 2026-09-28 13:50 UTCEPSS rescoreEPSS 0.6% · 47th percentile

Frequently asked(5)

What is CVE-2024-7521?
CVE-2024-7521 is a critical-severity vulnerability; its CVE record was published on August 6, 2024. Incomplete WebAssembly exception handing could have led to a use-after-free. This vulnerability affects Firefox < 129, Firefox ESR < 115.14, Firefox ESR < 128.1, Thunderbird < 128.1, and Thunderbird < 115.14.
When was the CVE record for CVE-2024-7521 published?
The CVE record for CVE-2024-7521 was published on August 6, 2024. 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 August 12, 2024; the record at its source may have been updated since.
Is CVE-2024-7521 actively exploited?
CVE-2024-7521 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.6% probability of exploitation in the next 30 days (49th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2024-7521?
CVE-2024-7521 has a CVSS v3 base score of 8.8 (NVD). EchelonGraph synthesises NVD + FIRST EPSS + GHSA into a combined EG score of 9.8 (CRITICAL).
How do I remediate CVE-2024-7521?
A fix for CVE-2024-7521 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2024-7521 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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