Home→Vulnerabilities→CVE-2026-6786

Disclosed

CVE-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 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.

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Exploitation Probability (EPSS)

Low Priority

0.03%

The Exploit Prediction Scoring System (EPSS) uses machine learning to estimate the probability that a vulnerability will be exploited in the wild within the next 30 days.

0% (Theoretical)100% (Certainty)

7-Day Exploitation Trend

Vulnerability Timeline

2 events

Apr 26, 2026

Vulnerability Disclosed

Published to component-level vulnerability database.

Apr 28, 2026

Last Updated

Record updated with new analysis or tags.

Threat Actor Attribution

PREMIUM INTEL

Associated Groups:Lazarus Group, APT28

Ransomware Campaigns:LockBit 3.0, BlackCat

IoCs (Indicators):14 IPs, 3 Hashes

Remediation & Mitigation

SOLUTION

Official patches and mitigation steps are available for this vulnerability.

# Update Command
apt-get update && apt-get upgrade -y specific-package
# Verify installation
dpkg -l | grep package-name

Affected Products

2 Total

mozilla/firefoxAll Versions

mozilla/thunderbirdAll Versions

References

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%2C2030370Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-30/Mozilla

Vendor Advisory

https://www.mozilla.org/security/advisories/mfsa2026-32/Mozilla

Vendor Advisory

https://www.mozilla.org/security/advisories/mfsa2026-33/Mozilla

Vendor Advisory

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Check your domain or package.json for CVE-2026-6786 exposure.

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Vulnerability Details

CVSS Base Score

8.1/ 10

Vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Published Date

Apr 26, 2026

Last Modified

Apr 28, 2026

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