Firefox <149 Mitigation Bypass in Networking:HTTP Component
CVE-2026-4700 Published on March 24, 2026
Mitigation bypass in the Networking: HTTP component
Mitigation bypass in the Networking: HTTP component. This vulnerability was fixed in Firefox 149, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.
Vulnerability Analysis
CVE-2026-4700 is exploitable with network access, requires user interaction. This vulnerability is consided to have a high level of attack complexity. The potential impact of an exploit of this vulnerability is considered to be very high.
Weakness Types
Authentication Bypass Using an Alternate Path or Channel
A product requires authentication, but the product has an alternate path or channel that does not require authentication.
What is a HTTP Request Smuggling Vulnerability?
When malformed or abnormal HTTP requests are interpreted by one or more entities in the data flow between the user and the web server, such as a proxy or firewall, they can be interpreted inconsistently, allowing the attacker to "smuggle" a request to one device without the other device being aware of it.
CVE-2026-4700 has been classified to as a HTTP Request Smuggling vulnerability or weakness.
Products Associated with CVE-2026-4700
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Affected Versions
Mozilla Firefox:- Version 140.9, <= 140.* is unaffected.
- Version 149, <= * is unaffected.
- Version 140.9, <= 140.* is unaffected.
- Version 149, <= * is unaffected.
- Version 0:140.9.0-1.el10_1 and below * is unaffected.
- Version 0:140.9.0-1.el10_1 and below * is unaffected.
- Version 0:140.9.0-1.el10_0 and below * is unaffected.
- Version 0:140.9.0-1.el10_0 and below * is unaffected.
- Version 0:140.9.0-1.el7_9 and below * is unaffected.
- Version 0:140.9.0-1.el8_10 and below * is unaffected.
- Version 0:140.9.0-1.el8_10 and below * is unaffected.
- Version 0:140.9.0-1.el8_2 and below * is unaffected.
- Version 0:140.9.0-1.el8_2 and below * is unaffected.
- Version 0:140.9.0-1.el8_4 and below * is unaffected.
- Version 0:140.9.0-1.el8_4 and below * is unaffected.
- Version 0:140.9.0-1.el8_4 and below * is unaffected.
- Version 0:140.9.0-1.el8_4 and below * is unaffected.
- Version 0:140.9.0-1.el8_6 and below * is unaffected.
- Version 0:140.9.0-1.el8_6 and below * is unaffected.
- Version 0:140.9.0-1.el8_6 and below * is unaffected.
- Version 0:140.9.0-1.el8_6 and below * is unaffected.
- Version 0:140.9.0-1.el8_6 and below * is unaffected.
- Version 0:140.9.0-1.el8_6 and below * is unaffected.
- Version 0:140.9.0-1.el8_8 and below * is unaffected.
- Version 0:140.9.0-1.el8_8 and below * is unaffected.
- Version 0:140.9.0-1.el8_8 and below * is unaffected.
- Version 0:140.9.0-1.el8_8 and below * is unaffected.
- Version 0:140.9.0-1.el9_7 and below * is unaffected.
- Version 0:140.9.0-1.el9_7 and below * is unaffected.
- Version 0:140.9.0-1.el9_0 and below * is unaffected.
- Version 0:140.9.0-1.el9_0 and below * is unaffected.
- Version 0:140.9.0-1.el9_2 and below * is unaffected.
- Version 0:140.9.0-1.el9_2 and below * is unaffected.
- Version 0:140.9.0-1.el9_4 and below * is unaffected.
- Version 0:140.9.0-1.el9_4 and below * is unaffected.
- Version 0:140.9.0-1.el9_6 and below * is unaffected.
- Version 0:140.9.0-1.el9_6 and below * is unaffected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.