CVE-2018-18500

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2022-05-14. 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 weekElevated
9.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 13%CVSS: 9.8Exploit: NoneExposed: 0

A fix is available — apply it.

A use-after-free vulnerability can occur while parsing an HTML5 stream in concert with custom HTML elements. This results in the stream parser object being freed while still in use, leading to a potentially exploitable crash. This vulnerability affects Thunderbird < 60.5, Firefox ESR < 60.5, and Firefox < 65.

CVSS v3
9.8
EG Score
9.8(medium)
EG Risk
65(Track*)
EG Risk 65/100SSVC: Track*

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
Severity98% × 45%
Exploitation40% × 40%
Automatability30% × 15%
Action: Watch closely — could escalate to Attend.
EPSS
95.8%
KEV
Not listed

Published

February 5, 2019

Last Modified

November 21, 2024

Advisory Details (9)

Auto-updated Jun 7, 2026
Patch available. Sources: redhat.
generic

Mozilla Thunderbird and Firefox: Multiple vulnerabilities (GLSA 201904-07) — Gentoo security

https://security.gentoo.org/glsa/201904-07
generic

Mozilla Firefox: Multiple vulnerabilities (GLSA 201903-04) — Gentoo security

https://security.gentoo.org/glsa/201903-04
generic Patch Available

[SECURITY] [DLA 1678-1] thunderbird security update

https://lists.debian.org/debian-lts-announce/2019/02/msg00024.html
generic Patch Available

[SECURITY] [DLA 1648-1] firefox-esr security update

https://lists.debian.org/debian-lts-announce/2019/01/msg00025.html
redhat Patch Available

Affected: Red Hat Enterprise Linux 7.

https://access.redhat.com/errata/RHSA-2019:0270
redhat Patch Available

Affected: Red Hat Enterprise Linux 6.

https://access.redhat.com/errata/RHSA-2019:0269
redhat Patch Available

Affected: Red Hat Enterprise Linux 7.

https://access.redhat.com/errata/RHSA-2019:0219
redhat Patch Available

Affected: Red Hat Enterprise Linux 6.

https://access.redhat.com/errata/RHSA-2019:0218
generic
http://www.securityfocus.com/bid/106781

Patch Availability(6)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntuxul-ext-lightning (1:60.5.1+build2-0ubuntu0.18.10.1) @ cosmic2026-05-27ubuntu
ubuntufirefox-testsuite (65.0+build2-0ubuntu0.14.04.1) @ trusty2026-05-27ubuntu
redhatthunderbird-0:60.5.0-1.el7_62019-02-04redhat
redhatthunderbird-0:60.5.0-1.el6_102019-02-04redhat
redhatfirefox-0:60.5.0-2.el62019-01-30redhat
redhatfirefox-0:60.5.0-2.el72019-01-30redhat

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.

All Vendor Advisories

(6)

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 11× in last 7d / 43× 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. 2026-07-23 14:15 UTCEPSS rescore
  2. 2026-07-23 01:34 UTCEG score recompute
  3. 2026-07-22 22:14 UTCEG score recompute
  4. 2026-07-22 14:05 UTCEPSS rescore
  5. 2026-07-21 15:22 UTCEPSS rescore
  6. 2026-07-20 23:02 UTCOSV refresh
  7. 2026-07-20 17:04 UTCEPSS rescore
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  1. 2026-07-05 02:27 UTCEPSS rescore
  2. 2026-07-04 06:28 UTCEPSS rescore
  3. 2026-07-04 06:28 UTCEPSS rescore
  4. 2026-07-03 18:26 UTCOSV refresh
  5. 2026-07-02 16:54 UTCEPSS rescore
  6. 2026-07-01 15:03 UTCEPSS rescore
  7. 2026-07-01 15:03 UTCEPSS rescore
  8. 2026-06-30 23:20 UTCEPSS rescore
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  10. 2026-06-28 14:04 UTCEPSS rescore
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  19. 2026-06-23 21:30 UTCEPSS rescore
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  22. 2026-06-22 14:23 UTCEPSS rescore
  23. 2026-06-21 14:54 UTCEPSS rescore
  24. 2026-06-21 14:54 UTCEPSS rescore
  25. 2026-06-21 01:57 UTCEPSS rescore
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  27. 2026-06-18 17:50 UTCEPSS rescore
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  34. 2026-06-15 06:43 UTCOSV refresh
  35. 2026-06-13 22:58 UTCEPSS rescore
  36. 2026-06-12 23:09 UTCEPSS rescore
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  38. 2026-06-11 13:57 UTCEPSS rescore
  39. 2026-06-10 22:16 UTCEPSS rescore
  40. 2026-06-10 13:19 UTCEPSS rescore
  41. 2026-06-07 15:22 UTCEPSS rescore
  42. 2026-06-07 15:22 UTCEPSS rescore
  43. 2026-06-06 13:45 UTCEPSS rescore
  44. 2026-06-06 13:45 UTCEPSS rescore
  45. 2026-06-05 22:45 UTCEPSS rescore
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  47. 2026-06-05 06:08 UTCEPSS rescore
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  49. 2026-06-04 13:10 UTCEPSS rescore
  50. 2026-06-02 20:11 UTCEPSS rescore
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  52. 2026-06-01 13:50 UTCEPSS rescore
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  54. 2026-05-31 22:29 UTCEPSS rescore
  55. 2026-05-31 00:14 UTCEPSS rescore
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  57. 2026-05-29 13:41 UTCEPSS rescore
  58. 2026-05-28 13:42 UTCEPSS rescore
  59. 2026-05-28 13:42 UTCEPSS rescore
  60. 2026-05-27 22:44 UTCEG score recompute
  61. 2026-05-27 22:44 UTCVendor advisory
  62. 2026-05-27 22:44 UTCGHSA enrichment
  63. 2026-05-27 13:38 UTCEPSS rescore
  64. 2026-05-27 13:38 UTCEPSS rescore
  65. 2026-05-26 13:42 UTCEPSS rescore
  66. 2026-05-26 13:42 UTCEPSS rescore
  67. 2026-05-25 07:07 UTCOSV refresh

Publicly available exploits

(1 reference)

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

  • GitHub PoCsophoslabs/CVE-2018-18500
    First seen Apr 18, 2019

    PoC for CVE-2018-18500 - Firefox Use-After-Free

    Open source ↗

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2018-18500?
CVE-2018-18500 is a critical vulnerability published on February 5, 2019. A use-after-free vulnerability can occur while parsing an HTML5 stream in concert with custom HTML elements. This results in the stream parser object being freed while still in use, leading to a potentially exploitable crash. This vulnerability affects Thunderbird < 60.5, Firefox ESR < 60.5, and…
When was CVE-2018-18500 disclosed?
CVE-2018-18500 was first published in the National Vulnerability Database on February 5, 2019, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2018-18500 actively exploited?
CVE-2018-18500 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 95.8% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2018-18500?
CVE-2018-18500 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2018-18500?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2018-18500, 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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