CVE-2023-5176

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2023-09-27. NVD baseline CVSS 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1.4%CVSS: 9.8Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

Memory safety bugs present in Firefox 117, Firefox ESR 115.2, and Thunderbird 115.2. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 118, Firefox ESR < 115.3, and Thunderbird < 115.3.

CVSS v3
9.8
EG Score
9.8CRITICALmedium confidence
EG Risk
60
EG Risk 60/100CISA SSVC

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%
Exploitation1% × 40%
Automatability100% × 15%
CISA SSVC: Track at low or medium mission impact; Attend at high (mission-essential systems).
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
1.4%
EPSS %ILE
71st
KEV
Not listed

CISA SSVCTrack 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). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

September 27, 2023

Last Modified

June 17, 2026

Advisory Details (8)

Auto-updated Oct 4, 2026
Patch available.
genericMentions a patch (unverified)

[SECURITY] [DLA 3587-1] firefox-esr security update

https://lists.debian.org/debian-lts-announce/2023/09/msg00034.html
generic

Client Challenge

https://bugzilla.mozilla.org/buglist.cgi?bug_id=1836353%2C1842674%2C1843824%2C1843962%2C1848890%2C1850180%2C1850983%2C1851195
generic

Security Vulnerabilities fixed in Thunderbird 115.3 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2023-43/
generic

Security Vulnerabilities fixed in Firefox ESR 115.3 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2023-42/
generic

Security Vulnerabilities fixed in Firefox 118 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2023-41/
generic

[SECURITY] [DSA 5513-1] thunderbird security update

https://www.debian.org/security/2023/dsa-5513
generic

[SECURITY] [DSA 5506-1] firefox-esr security update

https://www.debian.org/security/2023/dsa-5506
genericMentions a patch (unverified)

[SECURITY] [DLA 3601-1] thunderbird security update

https://lists.debian.org/debian-lts-announce/2023/10/msg00015.html

Vendor Advisories for CVE-2023-5176(1)

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

Patch Availability(18)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntufirefox-mozsymbols (118.0.1+build1-0ubuntu0.20.04.1) @ focal2026-05-24ubuntu
ubuntuxul-ext-lightning (1:115.3.1+build1-0ubuntu0.22.04.2) @ jammy2026-05-24ubuntu
redhatfirefox-0:115.3.1-1.el7_92023-10-05redhat
redhatthunderbird-0:115.3.1-1.el7_92023-10-05redhat
redhatfirefox-0:115.3.1-1.el8_62023-10-04redhat
redhatfirefox-0:115.3.1-1.el8_22023-10-04redhat
redhatthunderbird-0:115.3.1-1.el8_42023-10-04redhat
redhatthunderbird-0:115.3.1-1.el8_62023-10-04redhat
redhatfirefox-0:115.3.1-1.el9_02023-10-04redhat
redhatthunderbird-0:115.3.1-1.el8_82023-10-04redhat
redhatthunderbird-0:115.3.1-1.el8_12023-10-04redhat
redhatfirefox-0:115.3.1-1.el9_22023-10-04redhat
redhatfirefox-0:115.3.1-1.el8_82023-10-04redhat
redhatthunderbird-0:115.3.1-1.el9_22023-10-04redhat
redhatthunderbird-0:115.3.1-1.el9_02023-10-04redhat
redhatfirefox-0:115.3.1-1.el8_12023-10-04redhat
redhatthunderbird-0:115.3.1-1.el8_22023-10-04redhat
redhatfirefox-0:115.3.1-1.el8_42023-10-04redhat

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

(10 across 5 ecosystems)
Debian:10(2)
PackageVulnerable rangeFix by version rangeDependents
firefox-esr102.1.0esr-1 ... 91.9.1esr-1~deb9u1 (219 versions)
  • every version up to 115.3.0esr-1~deb10u1: fixed in 115.3.0esr-1~deb10u1
—
thunderbird1:102.0.1-1 ... 1:91.9.0-1~deb9u1 (279 versions)
  • every version up to 1:115.3.1-1~deb10u1: fixed in 1:115.3.1-1~deb10u1
—
Debian:11(2)
PackageVulnerable rangeFix by version rangeDependents
firefox-esr102.1.0esr-1 ... 91.9.1esr-1~deb9u1 (117 versions)
  • every version up to 115.3.0esr-1~deb11u1: fixed in 115.3.0esr-1~deb11u1
—
thunderbird1:102.0.1-1 ... 1:91.9.0-1~deb9u1 (156 versions)
  • every version up to 1:115.3.1-1~deb11u1: fixed in 1:115.3.1-1~deb11u1
—
Debian:12(2)
PackageVulnerable rangeFix by version rangeDependents
firefox-esr102.11.0esr-1 ... 115.3.0esr-1~deb11u1 (24 versions)
  • every version up to 115.3.0esr-1~deb12u1: fixed in 115.3.0esr-1~deb12u1
—
thunderbird1:102.11.0-1 ... 1:115.3.1-1~deb11u1 (41 versions)
  • every version up to 1:115.3.1-1~deb12u1: fixed in 1:115.3.1-1~deb12u1
—
Debian:13(2)
PackageVulnerable rangeFix by version rangeDependents
firefox-esr—
  • every version up to 115.3.0esr-1: fixed in 115.3.0esr-1
—
thunderbird—
  • every version up to 1:115.3.0-1: fixed in 1:115.3.0-1
—
Debian:14(2)
PackageVulnerable rangeFix by version rangeDependents
firefox-esr—
  • every version up to 115.3.0esr-1: fixed in 115.3.0esr-1
—
thunderbird—
  • every version up to 1:115.3.0-1: fixed in 1:115.3.0-1
—

Weakness Classification(1)

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

All Vendor Advisories

(18)

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 7× in last 7d / 30× 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 177 total refreshes for this CVE.

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

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Frequently asked(5)

What is CVE-2023-5176?
CVE-2023-5176 is a critical vulnerability published on September 27, 2023. Memory safety bugs present in Firefox 117, Firefox ESR 115.2, and Thunderbird 115.2. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 118, Firefox ESR <…
When was CVE-2023-5176 disclosed?
CVE-2023-5176 was first published on September 27, 2023, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2023-5176 actively exploited?
CVE-2023-5176 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1.4% probability of exploitation in the next 30 days (71st percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2023-5176?
CVE-2023-5176 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2023-5176?
A fix for CVE-2023-5176 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2023-5176 are linked in the Vendor Advisories panel on this page.

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