CVE-2019-17026

CRITICALNVD 8.89.0▲
EchelonGraph scoreHIGH confidence

Score elevated to 9.0 because this CVE is listed on the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03), indicating real-world exploitation has been confirmed by US federal agencies. NVD baseline CVSS 8.8 retained for reference. Confidence: HIGH.

Triggered by: CISA KEV (actively exploited)
Sources: cisa_kev, epss, ghsa, nvd
Trending — 5 sources updated this weekExploited in the wild
9.0EG
EchelonGraph verdictPatch nowTreat as an emergency — this is being exploited.
  • Actively exploited in the wild (CISA-KEV)
CISA-KEV: ExploitedEPSS PROB: 46%CVSS: 8.8Exploit: cisa kev · ssvc active · epss top5pct · public exploitExposed: 0

A fix is available — apply it.

Incorrect alias information in IonMonkey JIT compiler for setting array elements could lead to a type confusion. We are aware of targeted attacks in the wild abusing this flaw. This vulnerability affects Firefox ESR < 68.4.1, Thunderbird < 68.4.1, and Firefox < 72.0.1.

CVSS v3
8.8
EG Score
9.0(high)
EG Risk
81(Attend)
EG Risk 81/100SSVC: Attend

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
Severity90% × 45%
Exploitation100% × 40%
Automatability0% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
46%
EPSS %ILE
99%
KEV
⚠ Exploited

Published

March 2, 2020

Last Modified

November 4, 2025

Advisory Details (5)

Auto-updated Jun 1, 2026
⚠️ Active exploitation confirmed. No patch confirmed yet.
generic

Mozilla Firefox: Multiple vulnerabilities (GLSA 202003-02) — Gentoo security

https://security.gentoo.org/glsa/202003-02
generic🔴 Active Exploitation

1607443 - (CVE-2019-17026) In-the-wild 0-day reported by Qihoo 360

https://bugzilla.mozilla.org/show_bug.cgi?id=1607443
generic

Packet Storm

http://packetstormsecurity.com/files/162568/Firefox-72-IonMonkey-JIT-Type-Confusion.html
generic🔴 Active Exploitation

Security Vulnerabilities fixed in Thunderbird 68.4.1 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2020-04/
generic🔴 Active Exploitation

Security Vulnerabilities fixed in Firefox 72.0.1 and Firefox ESR 68.4.1 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2020-03/

Patch Availability(11)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntuxul-ext-lightning (1:68.7.0+build1-0ubuntu0.16.04.2) @ xenial2026-09-19ubuntu
ubuntufirefox-mozsymbols (72.0.1+build1-0ubuntu0.16.04.1) @ xenial2026-09-19ubuntu
ubuntuxul-ext-lightning (1:68.4.1+build1-0ubuntu0.19.10.1) @ eoan2026-09-19ubuntu
redhatthunderbird-0:68.4.1-2.el8_02020-01-30redhat
redhatfirefox-0:68.4.1-1.el8_02020-01-30redhat
redhatthunderbird-0:68.4.1-2.el7_72020-01-16redhat
redhatthunderbird-0:68.4.1-2.el6_102020-01-16redhat
redhatthunderbird-0:68.4.1-2.el8_12020-01-16redhat
redhatfirefox-0:68.4.1-1.el8_12020-01-14redhat
redhatfirefox-0:68.4.1-1.el7_72020-01-13redhat
redhatfirefox-0:68.4.1-1.el6_102020-01-13redhat

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

(14 across 7 ecosystems)
Debian:10(2)
PackageVulnerable rangeFixed inDependents
firefox-esr60.7.2esr-1 ... 68.4.1esr-1~deb9u1 (26 versions)68.4.1esr-1~deb10u1—
thunderbird1:60.7.2-1 ... 1:68.4.1-1~deb9u1 (29 versions)1:68.4.1-1~deb10u1—
Debian:11(2)
PackageVulnerable rangeFixed inDependents
firefox-esr—68.4.1esr-1—
thunderbird—1:68.4.1-1—
Debian:12(2)
PackageVulnerable rangeFixed inDependents
firefox-esr—68.4.1esr-1—
thunderbird—1:68.4.1-1—
Debian:13(2)
PackageVulnerable rangeFixed inDependents
firefox-esr—68.4.1esr-1—
thunderbird—1:68.4.1-1—
Debian:14(2)
PackageVulnerable rangeFixed inDependents
firefox-esr—68.4.1esr-1—
thunderbird—1:68.4.1-1—
Debian:8(2)
PackageVulnerable rangeFixed inDependents
firefox-esr45.0.1esr-1 ... 68.4.0esr-1~deb9u1 (170 versions)68.4.1esr-1~deb8u1—
thunderbird1.5-4 ... 1:68.3.1-1 (109 versions)1:68.4.1-1~deb8u1—
Debian:9(2)
PackageVulnerable rangeFixed inDependents
firefox-esr45.9.0esr-1 ... 68.4.1esr-1~deb8u1 (133 versions)68.4.1esr-1~deb9u1—
thunderbird1.5-4 ... 1:68.4.1-1~deb8u1 (110 versions)1:68.4.1-1~deb9u1—

Weakness Classification(1)

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

All Vendor Advisories

(11)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 107× in last 7d / 449× 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.

Showing the most recent 100 of 1,617 total refreshes for this CVE.

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

Publicly available exploits

(3 references)

Working exploit code is in the public domain (2 GitHub PoCs) (1 Exploit-DB entry). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • Exploit-DBEDB-49864
    First seen May 13, 2021

    Firefox 72 IonMonkey - JIT Type Confusion

    Open source ↗
  • GitHub PoClsw29475/CVE-2019-17026
    First seen Feb 24, 2021
    Open source ↗
  • GitHub PoCmaxpl0it/CVE-2019-17026-Exploit
    First seen Aug 27, 2020

    An exploit for CVE-2019-17026. It pops xcalc and was tested on Ubuntu (x64).

    Open source ↗

Frequently asked(6)

What is CVE-2019-17026?
CVE-2019-17026 is a critical vulnerability published on March 2, 2020. Incorrect alias information in IonMonkey JIT compiler for setting array elements could lead to a type confusion. We are aware of targeted attacks in the wild abusing this flaw. This vulnerability affects Firefox ESR < 68.4.1, Thunderbird < 68.4.1, and Firefox < 72.0.1.
When was CVE-2019-17026 disclosed?
CVE-2019-17026 was first published in the National Vulnerability Database on March 2, 2020, with the most recent update on November 4, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2019-17026 actively exploited?
Yes. CISA added CVE-2019-17026 to the Known Exploited Vulnerabilities catalog on November 3, 2021, affecting Mozilla Firefox and Thunderbird. KEV listing indicates confirmed exploitation in the wild; this CVE warrants immediate patching attention.
What is the CVSS score of CVE-2019-17026?
CVE-2019-17026 has a CVSS v3 base score of 8.8 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.0.
Which products are affected by CVE-2019-17026?
CVE-2019-17026 affects Mozilla Firefox and Thunderbird. The full affected-products list, including version ranges and fixed versions, is shown in the Affected Packages section of this page.
How do I remediate CVE-2019-17026?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2019-17026, 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.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2019-17026

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