CVE-2026-74963
published 2026-08-18CVE-2026-74963: Same-origin policy bypass in the Networking: Cookies component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird…
PriorityP426medium5.4CVSS 3.1
AVNACLPRNUIRSUCLILAN
EPSS
0.12%
2.4th percentile
Same-origin policy bypass in the Networking: Cookies component. 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
15 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| mozilla | firefox | < Firefox 154 | Firefox 154 |
| mozilla | firefox | < 140.14.0 | 140.14.0 |
| mozilla | firefox | < 154.0.0 | 154.0.0 |
| mozilla | firefox | — | — |
| mozilla | firefox_esr | < Firefox ESR 153.1 | Firefox ESR 153.1 |
| mozilla | firefox_esr | < Firefox ESR 140.14 | Firefox ESR 140.14 |
| mozilla | thunderbird | < Thunderbird 140.14 | Thunderbird 140.14 |
| mozilla | thunderbird | < Thunderbird 153.1 | Thunderbird 153.1 |
| mozilla | thunderbird | < Thunderbird 154 | Thunderbird 154 |
| mozilla | thunderbird | < 140.14.0 | 140.14.0 |
| mozilla | thunderbird | < 154.0 | 154.0 |
| mozilla | thunderbird | — | — |
| mozilla | thunderbird | >= 153.0 < 153.1.0 | 153.1.0 |
| rhel10 | firefox-flatpak | — | — |
| rhel10 | thunderbird-flatpak | — | — |
CVSS provenance
nvdv3.15.4MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
vendor_redhat5.4MEDIUM
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Red Hat
firefox: thunderbird: Same-origin policy bypass in the Networking: Cookies component
vendor_redhat·2026-08-18·CVSS 5.4
CVE-2026-74963 [MEDIUM] CWE-346 firefox: thunderbird: Same-origin policy bypass in the Networking: Cookies component
firefox: thunderbird: Same-origin policy bypass in the Networking: Cookies component
A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the following issue:
Same-origin policy bypass in the Networking: Cookies component
Statement: Red Hat Product Security rates the severity of this flaw as determined by the Mozilla Foundation Security Advisory.
Package: firefox (Red Hat Enterprise Linux 10) - Affected
Package: rhel10/firefox-flatpak (Red Hat Enterprise Linux 10) - Affected
Package: rhel10/thunderbird-flatpak (Red Hat Enterprise Linux 10) - Affected
Package: thunderbird (Red Hat Enterprise Linux 10) - Affected
Package: firefox (Red Hat Enterprise Linux 6) - Out of support scope
Package: thunderbird (Red Hat Enterprise Linux 6) - Out of
Mozilla
Mozilla Foundation Security Advisory 2026-77: CVE-2026-74963
vendor_mozilla
CVE-2026-74963 Mozilla Foundation Security Advisory 2026-77: CVE-2026-74963
Mozilla Foundation Security Advisory 2026-77
CVE: CVE-2026-74963
Product: Firefox ESR
Impact: high
Fixed in: Firefox ESR 153.1
Mozilla
Mozilla Foundation Security Advisory 2026-76: CVE-2026-74963
vendor_mozilla
CVE-2026-74963 Mozilla Foundation Security Advisory 2026-76: CVE-2026-74963
Mozilla Foundation Security Advisory 2026-76
CVE: CVE-2026-74963
Product: Firefox ESR
Impact: high
Fixed in: Firefox ESR 140.14
Mozilla
Mozilla Foundation Security Advisory 2026-79: CVE-2026-74963
vendor_mozilla
CVE-2026-74963 Mozilla Foundation Security Advisory 2026-79: CVE-2026-74963
Mozilla Foundation Security Advisory 2026-79
CVE: CVE-2026-74963
Product: Thunderbird
Impact: high
Fixed in: Thunderbird 140.14
Mozilla
Mozilla Foundation Security Advisory 2026-74: CVE-2026-74963
vendor_mozilla
CVE-2026-74963 Mozilla Foundation Security Advisory 2026-74: CVE-2026-74963
Mozilla Foundation Security Advisory 2026-74
CVE: CVE-2026-74963
Product: Firefox
Impact: high
Fixed in: Firefox 154
Mozilla
Mozilla Foundation Security Advisory 2026-80: CVE-2026-74963
vendor_mozilla
CVE-2026-74963 Mozilla Foundation Security Advisory 2026-80: CVE-2026-74963
Mozilla Foundation Security Advisory 2026-80
CVE: CVE-2026-74963
Product: Thunderbird
Impact: high
Fixed in: Thunderbird 153.1
Mozilla
Mozilla Foundation Security Advisory 2026-78: CVE-2026-74963
vendor_mozilla
CVE-2026-74963 Mozilla Foundation Security Advisory 2026-78: CVE-2026-74963
Mozilla Foundation Security Advisory 2026-78
CVE: CVE-2026-74963
Product: Thunderbird
Impact: high
Fixed in: Thunderbird 154
GHSA
Same-origin policy bypass in the Networking: Cookies component.
ghsa_unreviewed·2026-08-18
CVE-2026-74963 [MEDIUM] CWE-346 Same-origin policy bypass in the Networking: Cookies component.
Same-origin policy bypass in the Networking: Cookies component. 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/show_bug.cgi?id=2050482https://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