CVE-2026-74987
published 2026-08-18CVE-2026-74987: Internally found bugs present in Thunderbird ESR 140.13, Thunderbird ESR 153.0 and Thunderbird 153. Some of these bugs showed evidence of memory corruption or…
PriorityP352critical9.8CVSS 3.1
AVNACLPRNUINSUCHIHAH
EPSS
0.52%
42.3th percentile
Internally found bugs present in Thunderbird ESR 140.13, Thunderbird ESR 153.0 and Thunderbird 153. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
Affected
14 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| mozilla | firefox | < Firefox 154 | Firefox 154 |
| mozilla | firefox | < 140.14.0 | 140.14.0 |
| mozilla | firefox | — | — |
| mozilla | firefox | >= 141.0 < 153.1.0 | 153.1.0 |
| mozilla | firefox_esr | < Firefox ESR 140.14 | Firefox ESR 140.14 |
| mozilla | firefox_esr | < Firefox ESR 153.1 | Firefox ESR 153.1 |
| mozilla | thunderbird | < Thunderbird 154 | Thunderbird 154 |
| mozilla | thunderbird | < Thunderbird 153.1 | Thunderbird 153.1 |
| mozilla | thunderbird | < Thunderbird 140.14 | Thunderbird 140.14 |
| mozilla | thunderbird | < 140.14.0 | 140.14.0 |
| mozilla | thunderbird | — | — |
| mozilla | thunderbird | >= 141.0 < 153.1.0 | 153.1.0 |
| rhel10 | firefox-flatpak | — | — |
| rhel10 | thunderbird-flatpak | — | — |
CVSS provenance
nvdv3.19.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
vendor_redhat9.8CRITICAL
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Red Hat
firefox: thunderbird: Internally found bugs fixed in Firefox ESR 140.14, Firefox ESR 153.1 and Firefox 154
vendor_redhat·2026-08-18·CVSS 9.8
CVE-2026-74987 [CRITICAL] CWE-787 firefox: thunderbird: Internally found bugs fixed in Firefox ESR 140.14, Firefox ESR 153.1 and Firefox 154
firefox: thunderbird: Internally found bugs fixed in Firefox ESR 140.14, Firefox ESR 153.1 and Firefox 154
Internally found bugs present in Thunderbird ESR 140.13, Thunderbird ESR 153.0 and Thunderbird 153. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the following issue:
Internally found bugs present in Thunderbird ESR 140.13, Thunderbird ESR 153.0 and Thunderbird 153. Some of these bugs showed evidence of memory corruption
Mozilla
Mozilla Foundation Security Advisory 2026-76: CVE-2026-74987
vendor_mozilla
CVE-2026-74987 Mozilla Foundation Security Advisory 2026-76: CVE-2026-74987
Mozilla Foundation Security Advisory 2026-76
CVE: CVE-2026-74987
Product: Firefox ESR
Impact: high
Fixed in: Firefox ESR 140.14
Mozilla
Mozilla Foundation Security Advisory 2026-78: CVE-2026-74987
vendor_mozilla
CVE-2026-74987 Mozilla Foundation Security Advisory 2026-78: CVE-2026-74987
Mozilla Foundation Security Advisory 2026-78
CVE: CVE-2026-74987
Product: Thunderbird
Impact: high
Fixed in: Thunderbird 154
Mozilla
Mozilla Foundation Security Advisory 2026-74: CVE-2026-74987
vendor_mozilla
CVE-2026-74987 Mozilla Foundation Security Advisory 2026-74: CVE-2026-74987
Mozilla Foundation Security Advisory 2026-74
CVE: CVE-2026-74987
Product: Firefox
Impact: high
Fixed in: Firefox 154
Mozilla
Mozilla Foundation Security Advisory 2026-80: CVE-2026-74987
vendor_mozilla
CVE-2026-74987 Mozilla Foundation Security Advisory 2026-80: CVE-2026-74987
Mozilla Foundation Security Advisory 2026-80
CVE: CVE-2026-74987
Product: Thunderbird
Impact: high
Fixed in: Thunderbird 153.1
Mozilla
Mozilla Foundation Security Advisory 2026-77: CVE-2026-74987
vendor_mozilla
CVE-2026-74987 Mozilla Foundation Security Advisory 2026-77: CVE-2026-74987
Mozilla Foundation Security Advisory 2026-77
CVE: CVE-2026-74987
Product: Firefox ESR
Impact: high
Fixed in: Firefox ESR 153.1
Mozilla
Mozilla Foundation Security Advisory 2026-79: CVE-2026-74987
vendor_mozilla
CVE-2026-74987 Mozilla Foundation Security Advisory 2026-79: CVE-2026-74987
Mozilla Foundation Security Advisory 2026-79
CVE: CVE-2026-74987
Product: Thunderbird
Impact: high
Fixed in: Thunderbird 140.14
GHSA
Internally found bugs present in Firefox ESR 140.13, Firefox ESR 153.0 and Firefox 153.
ghsa_unreviewed·2026-08-18
CVE-2026-74987 [CRITICAL] CWE-119 Internally found bugs present in Firefox ESR 140.13, Firefox ESR 153.0 and Firefox 153.
Internally found bugs present in Firefox ESR 140.13, Firefox ESR 153.0 and Firefox 153. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, and Firefox ESR 153.1.
No detection rules found.
No public exploits indexed.
https://bugzilla.mozilla.org/buglist.cgi?bug_id=1500946%2C1788109%2C2045379%2C2045380%2C2049339%2C2049393%2C2053580%2C2054662%2C2054665%2C2054673%2C2054785%2C2058645https://bugzilla.mozilla.org/buglist.cgi?bug_id=2048797%2C2050536%2C2053272%2C2053579%2C2057115%2C2057116%2C2057130%2C2057991%2C2057995%2C2058002%2C2058008%2C2058032%2C2058102%2C2058667https://bugzilla.mozilla.org/show_bug.cgi?id=2059424https://www.mozilla.org/security/advisories/mfsa2026-74/https://www.mozilla.org/security/advisories/mfsa2026-76/https://www.mozilla.org/security/advisories/mfsa2026-77/https://www.mozilla.org/security/advisories/mfsa2026-78/https://www.mozilla.org/security/advisories/mfsa2026-79/https://www.mozilla.org/security/advisories/mfsa2026-80/
2026-08-18
Published