CVE-2026-2790: Same-origin policy bypass in the Networking: JAR component

Published Feb 24, 2026
·
Updated

Same-origin policy bypass in the Networking: JAR component. This vulnerability affects Firefox < 148 and Firefox ESR < 140.8.

Other sources

Same-origin policy bypass in the Networking: JAR component. This vulnerability was fixed in Firefox 148, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

— MITRE

Affected Software

8 affected componentsFixes available
Mozilla Firefox<148
148
Mozilla Firefox ESR<140.8
140.8
Mozilla Thunderbird<148
148
Mozilla Thunderbird<140.8
140.8
Mozilla Firefox<140.8.0
Mozilla Firefox<148.0
Mozilla Thunderbird<140.8.0
Mozilla Thunderbird<148.0

Event History

Feb 24, 2026
CVE Published
via Mozilla·12:00 AM
Data Sourced
via Mozilla·12:00 AM
DescriptionSeverityAffected Software
Updated
via Mozilla·12:00 AM
Affected Software
CVE Published
via MITRE·01:33 PM
Data Sourced
via MITRE·01:33 PM
Description
Data Sourced
via Red Hat·02:04 PM
DescriptionSeverityAffected Software
Data Sourced
via NVD·02:16 PM
DescriptionSeverityWeaknessAffected Software
Jan 4, 58137
Event
via FIRST·12:00 PM

Parent advisories

This vulnerability appears in the following advisories.

Peer vulnerabilities

Found alongside the following vulnerabilities.

Free Weekly Intel

Don't miss critical vulnerabilities

Join thousands of security professionals who receive our weekly digest of trending CVEs, zero-days, and exploited vulnerabilities.

No spam. Unsubscribe anytime.

Frequently Asked Questions

1

What is the severity of CVE-2026-2790?

CVE-2026-2790 is classified as a high-severity vulnerability due to its potential for bypassing the same-origin policy.

2

How do I fix CVE-2026-2790?

To fix CVE-2026-2790, update your Firefox browser to version 148 or higher, or Firefox ESR to version 140.8 or higher.

3

What products are affected by CVE-2026-2790?

CVE-2026-2790 affects Mozilla Firefox versions below 148 and Firefox ESR versions below 140.8.

4

What does the same-origin policy mean in relation to CVE-2026-2790?

The same-origin policy is a security measure that restricts how a document or script from one origin can interact with resources from another origin, and CVE-2026-2790 allows a bypass of this mechanism.

5

What are the potential impacts of CVE-2026-2790?

The potential impacts of CVE-2026-2790 include unauthorized access to sensitive data and possible exploitation of vulnerable systems.

Company

Resources

Contact

SecAlerts Pty Ltd.
132 Wickham Terrace
Fortitude Valley,
QLD 4006, Australia
info@secalerts.co
By using SecAlerts services, you agree to our services end-user license agreement. This website is safeguarded by reCAPTCHA and governed by the Google Privacy Policy and Terms of Service. All names, logos, and brands of products are owned by their respective owners, and any usage of these names, logos, and brands for identification purposes only does not imply endorsement. If you possess any content that requires removal, please get in touch with us.
© 2026 SecAlerts Pty Ltd.
ABN: 70 645 966 203, ACN: 645 966 203