CVE-2026-5734

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-04-07. 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: 0%CVSS: 9.8Exploit: None knownExposed: 0

A fix is available — apply it.

Memory safety bugs present in Firefox ESR 140.9.0, Thunderbird ESR 140.9.0, Firefox 149.0.1 and Thunderbird 149.0.1. 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 was fixed in Firefox 149.0.2, Firefox ESR 140.9.1, Thunderbird 149.0.2, and Thunderbird 140.9.1.

CVSS v3
9.8
EG Score
9.8(medium)
EG Risk
44(Track)
EG Risk 44/100SSVC: 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%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
26%
KEV
Not listed

Published

April 7, 2026

Last Modified

July 15, 2026

Advisory Details (10)

Auto-updated Sep 12, 2026
Patch available. Sources: redhat.
redhat Patch Available

Affected: Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions.

https://access.redhat.com/errata/RHSA-2026:13412
redhat Patch Available

Affected: Red Hat Enterprise Linux 9.6 Extended Update Support.

https://access.redhat.com/errata/RHSA-2026:13342
redhat Patch Available

Affected: Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions.

https://access.redhat.com/errata/RHSA-2026:12264
redhat Patch Available

Affected: Red Hat Enterprise Linux 10.0 Extended Update Support.

https://access.redhat.com/errata/RHSA-2026:11813
redhat Patch Available

Affected: Red Hat Enterprise Linux 8.2 Advanced Update Support.

https://access.redhat.com/errata/RHSA-2026:11805
generic

Security Vulnerabilities fixed in Thunderbird 140.9.1 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-29/
generic

Security Vulnerabilities fixed in Thunderbird 149.0.2 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-28/
generic

Security Vulnerabilities fixed in Firefox ESR 140.9.1 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-27/
generic

Security Vulnerabilities fixed in Firefox 149.0.2 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-25/
generic

Client Challenge

https://bugzilla.mozilla.org/buglist.cgi?bug_id=2022369%2C2023026%2C2023545%2C2023555%2C2023958%2C2025422%2C2025468%2C2025492%2C2025505

Vendor Advisories for CVE-2026-5734(20)

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

Patch Availability(24)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatthunderbird-0:140.9.1-1.el8_62026-05-11redhat
redhatthunderbird-0:140.9.1-1.el8_42026-05-06redhat
redhatfirefox-0:140.9.1-2.el7_92026-05-06redhat
redhatthunderbird-0:140.9.1-1.el8_82026-05-06redhat
redhatfirefox-0:140.9.1-1.el9_22026-05-06redhat
redhatfirefox-0:140.9.1-1.el9_62026-05-05redhat
redhatfirefox-0:140.9.1-1.el10_02026-05-05redhat
redhatfirefox-0:140.9.1-1.el9_02026-05-05redhat
redhatfirefox-0:140.9.1-1.el9_42026-05-05redhat
redhatfirefox-0:140.9.1-1.el8_62026-05-05redhat
redhatfirefox-0:140.9.1-1.el8_82026-05-05redhat
redhatfirefox-0:140.9.1-1.el8_42026-05-05redhat
redhatthunderbird-0:140.9.1-1.el9_62026-05-04redhat
redhatthunderbird-0:140.9.1-1.el9_22026-05-04redhat
redhatthunderbird-0:140.9.1-1.el9_42026-05-04redhat
redhatthunderbird-0:140.9.1-1.el9_02026-04-30redhat
redhatthunderbird-0:140.9.1-1.el10_02026-04-29redhat
redhatfirefox-0:140.9.1-1.el8_22026-04-29redhat
redhatthunderbird-0:140.9.1-1.el10_12026-04-22redhat
redhatthunderbird-0:140.9.1-1.el8_102026-04-21redhat
redhatthunderbird-0:140.9.1-1.el9_72026-04-16redhat
redhatfirefox-0:140.9.1-1.el8_102026-04-14redhat
redhatfirefox-0:140.9.1-1.el9_72026-04-13redhat
redhatfirefox-0:140.9.1-1.el10_12026-04-13redhat

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 rangeFixed inDependents
firefox-esr102.1.0esr-1 ... 91.9.1esr-1~deb9u1 (259 versions)140.9.1esr-1~deb11u1—
thunderbird1:102.0.1-1 ... 1:91.9.0-1~deb9u1 (310 versions)1:140.9.1esr-1~deb11u1—
Debian:12(2)
PackageVulnerable rangeFixed inDependents
firefox-esr102.11.0esr-1 ... 140.9.1esr-1~deb11u1 (166 versions)140.9.1esr-1~deb12u1—
thunderbird1:102.11.0-1 ... 1:140.9.1esr-1~deb11u1 (195 versions)1:140.9.1esr-1~deb12u1—
Debian:13(2)
PackageVulnerable rangeFixed inDependents
firefox-esr128.13.0esr-1 ... 140.9.1esr-1~deb12u1 (42 versions)140.9.1esr-1~deb13u1—
thunderbird1:128.13.0esr-1 ... 1:140.9.1esr-1~deb12u1 (51 versions)1:140.9.1esr-1~deb13u1—
Debian:14(2)
PackageVulnerable rangeFixed inDependents
firefox-esr128.13.0esr-1 ... 140.9.1esr-1~deb13u1 (43 versions)140.9.1esr-1—
thunderbird1:128.13.0esr-1 ... 1:140.9.1esr-1~deb13u1 (52 versions)1:140.9.1esr-1—

Weakness Classification(2)

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

Additional Vendor Advisories

(4)

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 5× in last 7d / 26× 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 269 total refreshes for this CVE.

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

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-5734?
CVE-2026-5734 is a critical vulnerability published on April 7, 2026. Memory safety bugs present in Firefox ESR 140.9.0, Thunderbird ESR 140.9.0, Firefox 149.0.1 and Thunderbird 149.0.1. 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 was…
When was CVE-2026-5734 disclosed?
CVE-2026-5734 was first published in the National Vulnerability Database on April 7, 2026, with the most recent update on July 15, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-5734 actively exploited?
CVE-2026-5734 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 74.1% of all scored CVEs.
What is the CVSS score of CVE-2026-5734?
CVE-2026-5734 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-5734?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-5734, 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-2026-5734

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