CVE-2026-100769
published 2026-09-29CVE-2026-100769: Use-after-free in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird…
PriorityP346high8.8CVSS 3.1
AVNACLPRNUIRSUCHIHAH
EPSS
0.31%
22.5th percentile
Use-after-free in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, and Firefox ESR 140.17.
Affected
15 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| mozilla | firefox | < Firefox 157 | Firefox 157 |
| mozilla | firefox | — | — |
| mozilla | firefox | >= 140.0.0 < 140.17.0 | 140.17.0 |
| mozilla | firefox | >= 153.0.0 < 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 140.17 | Firefox ESR 140.17 |
| mozilla | thunderbird | < Thunderbird 140.17 | Thunderbird 140.17 |
| mozilla | thunderbird | < Thunderbird 153.4 | Thunderbird 153.4 |
| mozilla | thunderbird | < Thunderbird 157 | Thunderbird 157 |
| mozilla | thunderbird | — | — |
| mozilla | thunderbird | >= 140.0 < 140.17.0 | 140.17.0 |
| mozilla | thunderbird | >= 153.0 < 153.4.0 | 153.4.0 |
| mozilla | thunderbird | >= 154.0 < 157.0 | 157.0 |
| rhel10 | thunderbird-flatpak | — | — |
CVSS provenance
nvdv3.18.8HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
vendor_redhat8.8HIGH
Stop checking back — get the weekly exploitation signal.
Every Monday: what got weaponized or added to CISA KEV in the last seven days — each CVE cross-linked to its PoC, Nuclei template, and detection rule. Free, one email a week, unsubscribe in one click.
Red Hat
firefox: thunderbird: Use-after-free in the JavaScript: WebAssembly component
vendor_redhat·2026-09-29·CVSS 8.8
CVE-2026-100769 [HIGH] CWE-416 firefox: thunderbird: Use-after-free in the JavaScript: WebAssembly component
firefox: thunderbird: Use-after-free in the JavaScript: WebAssembly component
Use-after-free in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, and Firefox ESR 140.17.
A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the following issue:
Use-after-free in the JavaScript: WebAssembly 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 criteria comprising ease of use and deployment, applicability to widespread i
Mozilla
Mozilla Foundation Security Advisory 2026-102: CVE-2026-100769
vendor_mozilla·CVSS 8.8
CVE-2026-100769 [HIGH] Mozilla Foundation Security Advisory 2026-102: CVE-2026-100769
Mozilla Foundation Security Advisory 2026-102
CVE: CVE-2026-100769
Product: Thunderbird
Impact: moderate
Fixed in: Thunderbird 140.17
Mozilla
Mozilla Foundation Security Advisory 2026-100: CVE-2026-100769
vendor_mozilla·CVSS 8.8
CVE-2026-100769 [HIGH] Mozilla Foundation Security Advisory 2026-100: CVE-2026-100769
Mozilla Foundation Security Advisory 2026-100
CVE: CVE-2026-100769
Product: Firefox ESR
Impact: low
Fixed in: Firefox ESR 153.4
Mozilla
Mozilla Foundation Security Advisory 2026-103: CVE-2026-100769
vendor_mozilla·CVSS 8.8
CVE-2026-100769 [HIGH] Mozilla Foundation Security Advisory 2026-103: CVE-2026-100769
Mozilla Foundation Security Advisory 2026-103
CVE: CVE-2026-100769
Product: Thunderbird
Impact: low
Fixed in: Thunderbird 153.4
Mozilla
Mozilla Foundation Security Advisory 2026-97: CVE-2026-100769
vendor_mozilla·CVSS 8.8
CVE-2026-100769 [HIGH] Mozilla Foundation Security Advisory 2026-97: CVE-2026-100769
Mozilla Foundation Security Advisory 2026-97
CVE: CVE-2026-100769
Product: Firefox
Impact: low
Fixed in: Firefox 157
Mozilla
Mozilla Foundation Security Advisory 2026-101: CVE-2026-100769
vendor_mozilla·CVSS 8.8
CVE-2026-100769 [HIGH] Mozilla Foundation Security Advisory 2026-101: CVE-2026-100769
Mozilla Foundation Security Advisory 2026-101
CVE: CVE-2026-100769
Product: Thunderbird
Impact: low
Fixed in: Thunderbird 157
Mozilla
Mozilla Foundation Security Advisory 2026-99: CVE-2026-100769
vendor_mozilla·CVSS 8.8
CVE-2026-100769 [HIGH] Mozilla Foundation Security Advisory 2026-99: CVE-2026-100769
Mozilla Foundation Security Advisory 2026-99
CVE: CVE-2026-100769
Product: Firefox ESR
Impact: moderate
Fixed in: Firefox ESR 140.17
VulDB
Mozilla Firefox up to 140.16/153.3/156 WebAssembly use after free (WID-SEC-2026-3654)
vuldb·2026-10-03·CVSS 8.8
CVE-2026-100769 [HIGH] Mozilla Firefox up to 140.16/153.3/156 WebAssembly use after free (WID-SEC-2026-3654)
A vulnerability, which was classified as critical, was found in Mozilla Firefox up to 140.16/153.3/156. This affects an unknown part of the component WebAssembly. The manipulation results in use after free.
This vulnerability is identified as CVE-2026-100769. The attack can be executed remotely. There is not any exploit available.
You should upgrade the affected component.
GHSA
Use-after-free in the JavaScript: WebAssembly component.
ghsa_unreviewed·2026-09-29
CVE-2026-100769 [HIGH] CWE-416 Use-after-free in the JavaScript: WebAssembly component.
Use-after-free in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox ESR 153.4, Firefox 157, and Firefox ESR 140.17.
No detection rules found.
No public exploits indexed.
https://bugzilla.mozilla.org/show_bug.cgi?id=2067190https://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/mfsa2026-99/
2026-09-29
Published