CVE-2026-100819
published 2026-09-29CVE-2026-100819: Sandbox escape due to incorrect boundary conditions in the XPCOM component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird…
PriorityP346critical9.6CVSS 3.1
AVNACLPRNUIRSCCHIHAH
EPSS
0.26%
16.4th percentile
Sandbox escape due to incorrect boundary conditions in the XPCOM component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.
Affected
18 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| mozilla | firefox | < Firefox 157 | Firefox 157 |
| mozilla | firefox | < 115.42.0 | 115.42.0 |
| mozilla | firefox | — | — |
| mozilla | firefox | >= 116.0 < 140.17.0 | 140.17.0 |
| mozilla | firefox | >= 141.0 < 153.4.0 | 153.4.0 |
| mozilla | firefox | >= 154.0.0 < 157.0.0 | 157.0.0 |
| mozilla | firefox_esr | < Firefox ESR 153.4 | Firefox ESR 153.4 |
| mozilla | firefox_esr | < Firefox ESR 115.42 | Firefox ESR 115.42 |
| mozilla | firefox_esr | < Firefox ESR 140.17 | Firefox ESR 140.17 |
| mozilla | thunderbird | < Thunderbird 157 | Thunderbird 157 |
| mozilla | thunderbird | < Thunderbird 140.17 | Thunderbird 140.17 |
| mozilla | thunderbird | < Thunderbird 153.4 | Thunderbird 153.4 |
| mozilla | thunderbird | < 140.17.0 | 140.17.0 |
| mozilla | thunderbird | — | — |
| mozilla | thunderbird | >= 141.0 < 153.4.0 | 153.4.0 |
| mozilla | thunderbird | >= 154.0 < 157.0 | 157.0 |
| rhel10 | firefox-flatpak | — | — |
| rhel10 | thunderbird-flatpak | — | — |
CVSS provenance
nvdv3.19.6CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
vendor_redhat9.6CRITICAL
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Red Hat
firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the XPCOM component
vendor_redhat·2026-09-29·CVSS 9.6
CVE-2026-100819 [CRITICAL] CWE-119 firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the XPCOM component
firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the XPCOM component
Sandbox escape due to incorrect boundary conditions in the XPCOM component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.
A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the following issue:
Sandbox escape due to incorrect boundary conditions in the XPCOM component
Statement: Red Hat Product Security rates the severity of this flaw as determined by the Mozilla Foundation Security Advisory.
Mitigation: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security
Mozilla
Mozilla Foundation Security Advisory 2026-97: CVE-2026-100819
vendor_mozilla·CVSS 9.6
CVE-2026-100819 [CRITICAL] Mozilla Foundation Security Advisory 2026-97: CVE-2026-100819
Mozilla Foundation Security Advisory 2026-97
CVE: CVE-2026-100819
Product: Firefox
Impact: low
Fixed in: Firefox 157
Mozilla
Mozilla Foundation Security Advisory 2026-101: CVE-2026-100819
vendor_mozilla·CVSS 9.6
CVE-2026-100819 [CRITICAL] Mozilla Foundation Security Advisory 2026-101: CVE-2026-100819
Mozilla Foundation Security Advisory 2026-101
CVE: CVE-2026-100819
Product: Thunderbird
Impact: low
Fixed in: Thunderbird 157
Mozilla
Mozilla Foundation Security Advisory 2026-102: CVE-2026-100819
vendor_mozilla·CVSS 9.6
CVE-2026-100819 [CRITICAL] Mozilla Foundation Security Advisory 2026-102: CVE-2026-100819
Mozilla Foundation Security Advisory 2026-102
CVE: CVE-2026-100819
Product: Thunderbird
Impact: moderate
Fixed in: Thunderbird 140.17
Mozilla
Mozilla Foundation Security Advisory 2026-100: CVE-2026-100819
vendor_mozilla·CVSS 9.6
CVE-2026-100819 [CRITICAL] Mozilla Foundation Security Advisory 2026-100: CVE-2026-100819
Mozilla Foundation Security Advisory 2026-100
CVE: CVE-2026-100819
Product: Firefox ESR
Impact: low
Fixed in: Firefox ESR 153.4
Mozilla
Mozilla Foundation Security Advisory 2026-103: CVE-2026-100819
vendor_mozilla·CVSS 9.6
CVE-2026-100819 [CRITICAL] Mozilla Foundation Security Advisory 2026-103: CVE-2026-100819
Mozilla Foundation Security Advisory 2026-103
CVE: CVE-2026-100819
Product: Thunderbird
Impact: low
Fixed in: Thunderbird 153.4
Mozilla
Mozilla Foundation Security Advisory 2026-98: CVE-2026-100819
vendor_mozilla·CVSS 9.6
CVE-2026-100819 [CRITICAL] Mozilla Foundation Security Advisory 2026-98: CVE-2026-100819
Mozilla Foundation Security Advisory 2026-98
CVE: CVE-2026-100819
Product: Firefox ESR
Impact: moderate
Fixed in: Firefox ESR 115.42
Mozilla
Mozilla Foundation Security Advisory 2026-99: CVE-2026-100819
vendor_mozilla·CVSS 9.6
CVE-2026-100819 [CRITICAL] Mozilla Foundation Security Advisory 2026-99: CVE-2026-100819
Mozilla Foundation Security Advisory 2026-99
CVE: CVE-2026-100819
Product: Firefox ESR
Impact: moderate
Fixed in: Firefox ESR 140.17
GHSA
Sandbox escape due to incorrect boundary conditions in the XPCOM component.
ghsa_unreviewed·2026-09-29
CVE-2026-100819 [CRITICAL] CWE-119 Sandbox escape due to incorrect boundary conditions in the XPCOM component.
Sandbox escape due to incorrect boundary conditions in the XPCOM component. This vulnerability was fixed in Firefox ESR 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.
No detection rules found.
No public exploits indexed.
https://bugzilla.mozilla.org/show_bug.cgi?id=2071069https://www.mozilla.org/security/advisories/mfsa2026-100/https://www.mozilla.org/security/advisories/mfsa2026-101/https://www.mozilla.org/security/advisories/mfsa2026-102/https://www.mozilla.org/security/advisories/mfsa2026-103/https://www.mozilla.org/security/advisories/mfsa2026-97/https://www.mozilla.org/security/advisories/mfsa2026-98/https://www.mozilla.org/security/advisories/mfsa2026-99/
2026-09-29
Published