CVE-2019-9791

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2022-05-24. NVD baseline CVSS 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 3 sources updated this weekWeaponized
9.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 20%CVSS: 9.8Exploit: NoneExposed: 0

A fix is available — apply it.

The type inference system allows the compilation of functions that can cause type confusions between arbitrary objects when compiled through the IonMonkey just-in-time (JIT) compiler and when the constructor function is entered through on-stack replacement (OSR). This allows for possible arbitrary reading and writing of objects during an exploitable crash. This vulnerability affects Thunderbird < 60.6, Firefox ESR < 60.6, and Firefox < 66.

CVSS v3
9.8
EG Score
9.8(medium)
EPSS
97.1%
KEV
Not listed

Published

April 26, 2019

Last Modified

November 25, 2025

Advisory Details (6)

Auto-updated Jun 23, 2026
Patch available. Sources: redhat.
generic

Security vulnerabilities fixed in Firefox 66 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2019-07/
generic

1530958 - (CVE-2019-9791) Spidermonkey: IonMonkey's type inference is incorrect for constructors entered via OSR

https://bugzilla.mozilla.org/show_bug.cgi?id=1530958
redhat Patch Available

Affected: Red Hat Enterprise Linux 8.

https://access.redhat.com/errata/RHSA-2019:1144
redhat Patch Available

Affected: Red Hat Enterprise Linux 8.

https://access.redhat.com/errata/RHSA-2019:0966
generic

Security vulnerabilities fixed in Thunderbird 60.6 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2019-11/
generic

Security vulnerabilities fixed in Firefox ESR 60.6 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2019-08/

Vendor Advisories for CVE-2019-9791(6)

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

Patch Availability(9)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntufirefox-testsuite (66.0+build3-0ubuntu0.16.04.2) @ xenial2026-05-27ubuntu
ubuntuxul-ext-lightning (1:60.6.1+build2-0ubuntu0.16.04.1) @ xenial2026-05-27ubuntu
ubuntufirefox-testsuite (66.0.1+build1-0ubuntu0.14.04.1) @ trusty2026-05-27ubuntu
redhatthunderbird-0:60.6.1-1.el82019-05-13redhat
redhatfirefox-0:60.6.1-1.el82019-05-07redhat
redhatthunderbird-0:60.6.1-1.el7_62019-03-28redhat
redhatthunderbird-0:60.6.1-1.el6_102019-03-28redhat
redhatfirefox-0:60.6.0-3.el7_62019-03-20redhat
redhatfirefox-0:60.6.0-3.el6_102019-03-20redhat

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(2)

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

Additional Vendor Advisories

(3)

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 11× in last 7d / 36× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. 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. Most recent first.

  1. 2026-07-22 22:30 UTCEG score recompute
  2. 2026-07-22 14:05 UTCEPSS rescore
  3. 2026-07-21 15:22 UTCEPSS rescore
  4. 2026-07-21 15:22 UTCEPSS rescore
  5. 2026-07-20 17:04 UTCEPSS rescore
  6. 2026-07-20 17:04 UTCOSV refresh
  7. 2026-07-19 02:26 UTCEPSS rescore
  8. 2026-07-19 02:26 UTCEPSS rescore
  9. 2026-07-18 10:02 UTCEPSS rescore
  10. 2026-07-16 16:59 UTCEPSS rescore
  11. 2026-07-16 16:59 UTCEPSS rescore
  12. 2026-07-15 16:55 UTCEPSS rescore
  13. 2026-07-13 22:27 UTCEPSS rescore
  14. 2026-07-12 05:44 UTCEPSS rescore
  15. 2026-07-11 08:24 UTCEPSS rescore
  16. 2026-07-09 19:06 UTCEPSS rescore
  17. 2026-07-08 15:11 UTCEPSS rescore
  18. 2026-07-07 13:43 UTCEPSS rescore
  19. 2026-07-06 16:25 UTCEPSS rescore
  20. 2026-07-06 16:25 UTCEPSS rescore
  21. 2026-07-06 02:20 UTCEPSS rescore
  22. 2026-07-05 02:27 UTCEPSS rescore
  23. 2026-07-04 06:28 UTCEPSS rescore
  24. 2026-07-03 12:26 UTCOSV refresh
  25. 2026-07-01 15:03 UTCEPSS rescore
Show 62 more
  1. 2026-07-01 15:03 UTCEPSS rescore
  2. 2026-06-28 14:05 UTCEPSS rescore
  3. 2026-06-28 04:54 UTCEPSS rescore
  4. 2026-06-28 04:54 UTCEPSS rescore
  5. 2026-06-27 03:06 UTCEPSS rescore
  6. 2026-06-25 13:47 UTCEPSS rescore
  7. 2026-06-25 13:47 UTCEPSS rescore
  8. 2026-06-24 14:03 UTCEPSS rescore
  9. 2026-06-24 14:03 UTCEPSS rescore
  10. 2026-06-23 21:31 UTCEPSS rescore
  11. 2026-06-23 21:31 UTCEPSS rescore
  12. 2026-06-22 14:23 UTCEPSS rescore
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  14. 2026-06-21 14:54 UTCEPSS rescore
  15. 2026-06-21 14:54 UTCEPSS rescore
  16. 2026-06-21 01:57 UTCEPSS rescore
  17. 2026-06-21 01:57 UTCEPSS rescore
  18. 2026-06-18 17:50 UTCEPSS rescore
  19. 2026-06-18 17:50 UTCEPSS rescore
  20. 2026-06-17 17:50 UTCEPSS rescore
  21. 2026-06-16 17:50 UTCEPSS rescore
  22. 2026-06-15 17:46 UTCEPSS rescore
  23. 2026-06-15 02:43 UTCOSV refresh
  24. 2026-06-14 23:15 UTCEPSS rescore
  25. 2026-06-14 23:15 UTCEPSS rescore
  26. 2026-06-13 22:58 UTCEPSS rescore
  27. 2026-06-12 23:09 UTCEPSS rescore
  28. 2026-06-12 23:09 UTCEPSS rescore
  29. 2026-06-11 13:58 UTCEPSS rescore
  30. 2026-06-10 22:16 UTCEPSS rescore
  31. 2026-06-10 22:16 UTCEPSS rescore
  32. 2026-06-10 13:19 UTCEPSS rescore
  33. 2026-06-08 14:15 UTCEPSS rescore
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  35. 2026-06-08 14:15 UTCEPSS rescore
  36. 2026-06-07 15:23 UTCEPSS rescore
  37. 2026-06-07 15:23 UTCEPSS rescore
  38. 2026-06-06 13:45 UTCEPSS rescore
  39. 2026-06-06 13:45 UTCEPSS rescore
  40. 2026-06-05 22:45 UTCEPSS rescore
  41. 2026-06-05 06:08 UTCEPSS rescore
  42. 2026-06-04 13:10 UTCEPSS rescore
  43. 2026-06-04 13:10 UTCEPSS rescore
  44. 2026-06-02 20:11 UTCEPSS rescore
  45. 2026-06-02 20:11 UTCEPSS rescore
  46. 2026-05-31 22:29 UTCEPSS rescore
  47. 2026-05-31 22:29 UTCEPSS rescore
  48. 2026-05-31 00:14 UTCEPSS rescore
  49. 2026-05-31 00:14 UTCEPSS rescore
  50. 2026-05-29 13:42 UTCEPSS rescore
  51. 2026-05-28 13:43 UTCEPSS rescore
  52. 2026-05-28 13:43 UTCEPSS rescore
  53. 2026-05-27 20:05 UTCEG score recompute
  54. 2026-05-27 20:05 UTCVendor advisory
  55. 2026-05-27 20:05 UTCGHSA enrichment
  56. 2026-05-27 13:39 UTCEPSS rescore
  57. 2026-05-27 13:38 UTCEPSS rescore
  58. 2026-05-26 13:42 UTCEPSS rescore
  59. 2026-05-26 07:17 UTCEPSS rescore
  60. 2026-05-26 07:17 UTCEPSS rescore
  61. 2026-05-26 07:17 UTCEPSS rescore
  62. 2026-05-24 20:12 UTCOSV refresh

Publicly available exploits

(2 references)

Working exploit code is in the public domain (1 GitHub PoC) (1 Exploit-DB entry). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoCSp0pielar/CVE-2019-9791
    First seen Sep 8, 2021

    Exploit chain for CVE-2019-9791 & CVE-2019-11708 against firefox 65.0 on windows 64bit

    Open source ↗
  • Exploit-DBEDB-46613✓ verified
    First seen Mar 26, 2019

    Spidermonkey - IonMonkey Type Inference is Incorrect for Constructors Entered via OSR

    Open source ↗

Frequently asked(5)

What is CVE-2019-9791?
CVE-2019-9791 is a critical vulnerability published on April 26, 2019. The type inference system allows the compilation of functions that can cause type confusions between arbitrary objects when compiled through the IonMonkey just-in-time (JIT) compiler and when the constructor function is entered through on-stack replacement (OSR). This allows for possible arbitrary…
When was CVE-2019-9791 disclosed?
CVE-2019-9791 was first published in the National Vulnerability Database on April 26, 2019, with the most recent update on November 25, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2019-9791 actively exploited?
CVE-2019-9791 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 97.1% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2019-9791?
CVE-2019-9791 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2019-9791?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2019-9791, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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