CVE-2026-6786
published 2026-04-26CVE-2026-6786: Memory safety bugs present in Firefox ESR 140.9, Thunderbird ESR 140.9, Firefox 149 and Thunderbird 149. Some of these bugs showed evidence of memory…
PriorityP344high7.5CVSS 3.1
AVNACHPRNUIRSUCHIHAH
EPSS
0.50%
39.5th percentile
Memory safety bugs present in Firefox ESR 140.9, Thunderbird ESR 140.9, Firefox 149 and Thunderbird 149. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10.
Affected
7 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| mozilla | firefox | < Firefox 150 | Firefox 150 |
| mozilla | firefox | < 150.0 | 150.0 |
| mozilla | firefox | >= 140.0 < 140.10.0 | 140.10.0 |
| mozilla | firefox_esr | < Firefox ESR 140.10 | Firefox ESR 140.10 |
| mozilla | thunderbird | < Thunderbird 140.10 | Thunderbird 140.10 |
| mozilla | thunderbird | < Thunderbird 150 | Thunderbird 150 |
| mozilla | thunderbird | >= 140.0 < 140.10.0 | 140.10.0 |
CVSS provenance
nvdv3.17.5HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
vendor_redhat8.1HIGH
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: Memory safety bugs fixed in Firefox ESR 140.10, Thunderbird ESR 140.10, Firefox 150 and Thunderbird 150
vendor_redhat·2026-04-21·CVSS 8.1
CVE-2026-6786 [HIGH] CWE-787 firefox: thunderbird: Memory safety bugs fixed in Firefox ESR 140.10, Thunderbird ESR 140.10, Firefox 150 and Thunderbird 150
firefox: thunderbird: Memory safety bugs fixed in Firefox ESR 140.10, Thunderbird ESR 140.10, Firefox 150 and Thunderbird 150
A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the following issue:
Memory safety bugs present in Firefox ESR 140.9, Thunderbird ESR 140.9, Firefox 149 and Thunderbird 149. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code.
Statement: Red Hat Product Security rates the severity of this flaw as determined by the Mozilla Foundation Security Advisory.
Mozilla
Mozilla Foundation Security Advisory 2026-34: CVE-2026-6786
vendor_mozilla·CVSS 8.1
CVE-2026-6786 [HIGH] Mozilla Foundation Security Advisory 2026-34: CVE-2026-6786
Mozilla Foundation Security Advisory 2026-34
CVE: CVE-2026-6786
Product: Thunderbird
Impact: high
Fixed in: Thunderbird 140.10
Mozilla
Mozilla Foundation Security Advisory 2026-32: CVE-2026-6786
vendor_mozilla·CVSS 8.1
CVE-2026-6786 [HIGH] Mozilla Foundation Security Advisory 2026-32: CVE-2026-6786
Mozilla Foundation Security Advisory 2026-32
CVE: CVE-2026-6786
Product: Firefox ESR
Impact: high
Fixed in: Firefox ESR 140.10
Mozilla
Mozilla Foundation Security Advisory 2026-33: CVE-2026-6786
vendor_mozilla·CVSS 8.1
CVE-2026-6786 [HIGH] Mozilla Foundation Security Advisory 2026-33: CVE-2026-6786
Mozilla Foundation Security Advisory 2026-33
CVE: CVE-2026-6786
Product: Thunderbird
Impact: high
Fixed in: Thunderbird 150
Mozilla
Mozilla Foundation Security Advisory 2026-30: CVE-2026-6786
vendor_mozilla·CVSS 8.1
CVE-2026-6786 [HIGH] Mozilla Foundation Security Advisory 2026-30: CVE-2026-6786
Mozilla Foundation Security Advisory 2026-30
CVE: CVE-2026-6786
Product: Firefox
Impact: high
Fixed in: Firefox 150
GHSA
GHSA-qh56-2ppp-52x2: Memory safety bugs present in Firefox ESR 140
ghsa_unreviewed·2026-04-26
CVE-2026-6786 [HIGH] CWE-125 GHSA-qh56-2ppp-52x2: Memory safety bugs present in Firefox ESR 140
Memory safety bugs present in Firefox ESR 140.9, Thunderbird ESR 140.9, Firefox 149 and Thunderbird 149. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10.
No detection rules found.
No public exploits indexed.
https://bugzilla.mozilla.org/buglist.cgi?bug_id=2010727%2C2019004%2C2019224%2C2019547%2C2020378%2C2022381%2C2022608%2C2022785%2C2023120%2C2023128%2C2023140%2C2023279%2C2023836%2C2023882%2C2023925%2C2023950%2C2023959%2C2023965%2C2024243%2C2024245%2C2024247%2C2024253%2C2024346%2C2024357%2C2024416%2C2024420%2C2024429%2C2024432%2C2024455%2C2024466%2C2024468%2C2024476%2C2024664%2C2024666%2C2024669%2C2024670%2C2024671%2C2024761%2C2024918%2C2025292%2C2025332%2C2025348%2C2025384%2C2025395%2C2025458%2C2025461%2C2025463%2C2025481%2C2025483%2C2025485%2C2025494%2C2025506%2C2025511%2C2025513%2C2025520%2C2026277%2C2026282%2C2026288%2C2026289%2C2026311%2C2026312%2C2026869%2C2027152%2C2027161%2C2027238%2C2027261%2C2027269%2C2027274%2C2027280%2C2027281%2C2027300%2C2027302%2C2027331%2C2027339%2C2027340%2C2027738%2C2027975%2C2028000%2C2028011%2C2028289%2C2028525%2C2028728%2C2028887%2C2028888%2C2028896%2C2029063%2C2029064%2C2029290%2C2029291%2C2029294%2C2029300%2C2029304%2C2029316%2C2029317%2C2029401%2C2029415%2C2029430%2C2029457%2C2029727%2C2029735%2C2029743%2C2029752%2C2029754%2C2029776%2C2029809%2C2030324%2C2030370https://www.mozilla.org/security/advisories/mfsa2026-30/https://www.mozilla.org/security/advisories/mfsa2026-32/https://www.mozilla.org/security/advisories/mfsa2026-33/https://www.mozilla.org/security/advisories/mfsa2026-34/https://access.redhat.com/errata/RHSA-2026:10757https://access.redhat.com/errata/RHSA-2026:10766https://access.redhat.com/errata/RHSA-2026:10767https://access.redhat.com/errata/RHSA-2026:12285https://access.redhat.com/errata/RHSA-2026:13537https://access.redhat.com/errata/RHSA-2026:15892https://access.redhat.com/errata/RHSA-2026:17477https://access.redhat.com/errata/RHSA-2026:17687https://access.redhat.com/errata/RHSA-2026:17688https://access.redhat.com/errata/RHSA-2026:17689https://access.redhat.com/errata/RHSA-2026:17690https://access.redhat.com/errata/RHSA-2026:19041https://access.redhat.com/errata/RHSA-2026:19131https://access.redhat.com/errata/RHSA-2026:19201https://access.redhat.com/errata/RHSA-2026:19348https://access.redhat.com/errata/RHSA-2026:19461https://access.redhat.com/errata/RHSA-2026:19462https://access.redhat.com/errata/RHSA-2026:19463https://access.redhat.com/errata/RHSA-2026:19464https://access.redhat.com/errata/RHSA-2026:19465https://access.redhat.com/errata/RHSA-2026:19466https://access.redhat.com/errata/RHSA-2026:19467https://access.redhat.com/errata/RHSA-2026:19468https://access.redhat.com/errata/RHSA-2026:19469https://access.redhat.com/errata/RHSA-2026:19542https://access.redhat.com/errata/RHSA-2026:19655https://access.redhat.com/errata/RHSA-2026:19704https://access.redhat.com/security/cve/CVE-2026-6786https://bugzilla.redhat.com/show_bug.cgi?id=2460088https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-6786.json
2026-04-26
Published