CVE-2026-100766
published 2026-09-29CVE-2026-100766: Information disclosure in the Networking: JAR component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird…
PriorityP419medium4.3CVSS 3.1
AVNACLPRNUIRSUCLINAN
EPSS
0.25%
15.4th percentile
Information disclosure in the Networking: JAR 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
17 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 | >= 116.0.0 < 140.17.0 | 140.17.0 |
| mozilla | firefox | >= 141.0.0 < 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 | firefox_esr | < Firefox ESR 115.42 | Firefox ESR 115.42 |
| mozilla | thunderbird | < Thunderbird 153.4 | Thunderbird 153.4 |
| mozilla | thunderbird | < Thunderbird 157 | Thunderbird 157 |
| mozilla | thunderbird | < Thunderbird 140.17 | Thunderbird 140.17 |
| 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 | thunderbird-flatpak | — | — |
CVSS provenance
nvdv3.14.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N
vendor_redhat4.3MEDIUM
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Red Hat
firefox: thunderbird: Information disclosure in the Networking: JAR component
vendor_redhat·2026-09-29·CVSS 4.3
CVE-2026-100766 [MEDIUM] CWE-200 firefox: thunderbird: Information disclosure in the Networking: JAR component
firefox: thunderbird: Information disclosure in the Networking: JAR component
Information disclosure in the Networking: JAR 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:
Information disclosure in the Networking: JAR 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, applicabi
Mozilla
Mozilla Foundation Security Advisory 2026-97: CVE-2026-100766
vendor_mozilla·CVSS 4.3
CVE-2026-100766 [MEDIUM] Mozilla Foundation Security Advisory 2026-97: CVE-2026-100766
Mozilla Foundation Security Advisory 2026-97
CVE: CVE-2026-100766
Product: Firefox
Impact: low
Fixed in: Firefox 157
Mozilla
Mozilla Foundation Security Advisory 2026-103: CVE-2026-100766
vendor_mozilla·CVSS 4.3
CVE-2026-100766 [MEDIUM] Mozilla Foundation Security Advisory 2026-103: CVE-2026-100766
Mozilla Foundation Security Advisory 2026-103
CVE: CVE-2026-100766
Product: Thunderbird
Impact: low
Fixed in: Thunderbird 153.4
Mozilla
Mozilla Foundation Security Advisory 2026-101: CVE-2026-100766
vendor_mozilla·CVSS 4.3
CVE-2026-100766 [MEDIUM] Mozilla Foundation Security Advisory 2026-101: CVE-2026-100766
Mozilla Foundation Security Advisory 2026-101
CVE: CVE-2026-100766
Product: Thunderbird
Impact: low
Fixed in: Thunderbird 157
Mozilla
Mozilla Foundation Security Advisory 2026-102: CVE-2026-100766
vendor_mozilla·CVSS 4.3
CVE-2026-100766 [MEDIUM] Mozilla Foundation Security Advisory 2026-102: CVE-2026-100766
Mozilla Foundation Security Advisory 2026-102
CVE: CVE-2026-100766
Product: Thunderbird
Impact: moderate
Fixed in: Thunderbird 140.17
Mozilla
Mozilla Foundation Security Advisory 2026-100: CVE-2026-100766
vendor_mozilla·CVSS 4.3
CVE-2026-100766 [MEDIUM] Mozilla Foundation Security Advisory 2026-100: CVE-2026-100766
Mozilla Foundation Security Advisory 2026-100
CVE: CVE-2026-100766
Product: Firefox ESR
Impact: low
Fixed in: Firefox ESR 153.4
Mozilla
Mozilla Foundation Security Advisory 2026-99: CVE-2026-100766
vendor_mozilla·CVSS 4.3
CVE-2026-100766 [MEDIUM] Mozilla Foundation Security Advisory 2026-99: CVE-2026-100766
Mozilla Foundation Security Advisory 2026-99
CVE: CVE-2026-100766
Product: Firefox ESR
Impact: moderate
Fixed in: Firefox ESR 140.17
Mozilla
Mozilla Foundation Security Advisory 2026-98: CVE-2026-100766
vendor_mozilla·CVSS 4.3
CVE-2026-100766 [MEDIUM] Mozilla Foundation Security Advisory 2026-98: CVE-2026-100766
Mozilla Foundation Security Advisory 2026-98
CVE: CVE-2026-100766
Product: Firefox ESR
Impact: moderate
Fixed in: Firefox ESR 115.42
VulDB
Mozilla Firefox up to 115.41/140.16/153.3/156 JAR information disclosure (WID-SEC-2026-3654)
vuldb·2026-10-03·CVSS 4.3
CVE-2026-100766 [MEDIUM] Mozilla Firefox up to 115.41/140.16/153.3/156 JAR information disclosure (WID-SEC-2026-3654)
A vulnerability was found in Mozilla Firefox up to 115.41/140.16/153.3/156 and classified as problematic. Affected by this issue is some unknown functionality of the component JAR. The manipulation results in information disclosure.
This vulnerability is cataloged as CVE-2026-100766. The attack may be launched remotely. There is no exploit available.
It is suggested to upgrade the affected component.
GHSA
Information disclosure in the Networking: JAR component.
ghsa_unreviewed·2026-09-29
CVE-2026-100766 [MEDIUM] CWE-200 Information disclosure in the Networking: JAR component.
Information disclosure in the Networking: JAR 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=2061526https://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