CVE-2026-4700
published 2026-03-24CVE-2026-4700: Mitigation bypass in the Networking: HTTP component. This vulnerability was fixed in Firefox 149, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.
PriorityP352critical9.8CVSS 3.1
AVNACLPRNUINSUCHIHAH
EPSS
0.46%
36.9th percentile
Mitigation bypass in the Networking: HTTP component. This vulnerability was fixed in Firefox 149, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.
Affected
10 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| debian | firefox | < firefox 149.0-1 (sid) | firefox 149.0-1 (sid) |
| debian | firefox-esr | < firefox 149.0-1 (sid) | firefox 149.0-1 (sid) |
| debian | thunderbird | < firefox 149.0-1 (sid) | firefox 149.0-1 (sid) |
| mozilla | firefox | < 140.9.0 | 140.9.0 |
| mozilla | firefox | < 149.0 | 149.0 |
| mozilla | firefox | — | — |
| mozilla | thunderbird | >= 0 < 1:140.9.0esr-1~deb11u1 | 1:140.9.0esr-1~deb11u1 |
| mozilla | thunderbird | >= 0 < 1:140.9.0esr-1~deb12u1 | 1:140.9.0esr-1~deb12u1 |
| mozilla | thunderbird | >= 0 < 1:140.9.0esr-1~deb13u1 | 1:140.9.0esr-1~deb13u1 |
| mozilla | thunderbird | >= 0 < 1:140.9.0esr-1 | 1:140.9.0esr-1 |
CVSS provenance
nvdv3.19.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
osv9.8CRITICAL
vendor_debian9.8CRITICAL
vendor_redhat9.8CRITICAL
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Red Hat
firefox: thunderbird: Mitigation bypass in the Networking: HTTP component
vendor_redhat·2026-03-24·CVSS 9.8
CVE-2026-4700 [CRITICAL] CWE-444 firefox: thunderbird: Mitigation bypass in the Networking: HTTP component
firefox: thunderbird: Mitigation bypass in the Networking: HTTP component
Mitigation bypass in the Networking: HTTP component. This vulnerability affects Firefox < 149, Firefox ESR < 140.9, Thunderbird < 149, and Thunderbird < 140.9.
A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the following issue:
Mitigation bypass in the Networking: HTTP component
Statement: Red Hat Product Security rates the severity of this flaw as determined by the Mozilla Foundation Security Advisory.
Package: rhel10/firefox-flatpak (Red Hat Enterprise Linux 10) - Affected
Package: rhel10/thunderbird-flatpak (Red Hat Enterprise Linux 10) - Affected
Package: firefox (Red Hat Enterprise Linux 6) - Out of support scope
Package: thunderbird (Red Hat Enterprise L
Debian
CVE-2026-4700: firefox - Mitigation bypass in the Networking: HTTP component. This vulnerability affects ...
vendor_debian·2026·CVSS 9.8
CVE-2026-4700 [CRITICAL] CVE-2026-4700: firefox - Mitigation bypass in the Networking: HTTP component. This vulnerability affects ...
Mitigation bypass in the Networking: HTTP component. This vulnerability affects Firefox < 149, Firefox ESR < 140.9, Thunderbird < 149, and Thunderbird < 140.9.
Scope: local
sid: resolved (fixed in 149.0-1)
Mozilla
Mozilla Foundation Security Advisory 2026-23: CVE-2026-4700
vendor_mozilla·CVSS 9.8
CVE-2026-4700 [CRITICAL] Mozilla Foundation Security Advisory 2026-23: CVE-2026-4700
Mozilla Foundation Security Advisory 2026-23
CVE: CVE-2026-4700
Product: Thunderbird
Impact: high
Fixed in: Thunderbird 149
Mozilla
Mozilla Foundation Security Advisory 2026-24: CVE-2026-4700
vendor_mozilla·CVSS 9.8
CVE-2026-4700 [CRITICAL] Mozilla Foundation Security Advisory 2026-24: CVE-2026-4700
Mozilla Foundation Security Advisory 2026-24
CVE: CVE-2026-4700
Product: Thunderbird
Impact: high
Fixed in: Thunderbird 140.9
Mozilla
Mozilla Foundation Security Advisory 2026-22: CVE-2026-4700
vendor_mozilla·CVSS 9.8
CVE-2026-4700 [CRITICAL] Mozilla Foundation Security Advisory 2026-22: CVE-2026-4700
Mozilla Foundation Security Advisory 2026-22
CVE: CVE-2026-4700
Product: Firefox ESR
Impact: high
Fixed in: Firefox ESR 140.9
Mozilla
Mozilla Foundation Security Advisory 2026-20: CVE-2026-4700
vendor_mozilla·CVSS 9.8
CVE-2026-4700 [CRITICAL] Mozilla Foundation Security Advisory 2026-20: CVE-2026-4700
Mozilla Foundation Security Advisory 2026-20
CVE: CVE-2026-4700
Product: Firefox
Impact: high
Fixed in: Firefox 149
Citrix
Citrix Security Bulletin CTX139591
vendor_citrix·CVSS 4.9
CVE-2014-4700 [MEDIUM] Citrix Security Bulletin CTX139591
Citrix Security Bulletin CTX139591
CVE References: CVE-2014-4700, CVE-2025-12101, CVE-2025-62626, CVE-2026-23554, CVE-2026-3055, CVE-2026-4368, CVE-2026-4397
Affected Products: Citrix ADM, Citrix Hypervisor, Citrix Virtual Apps and Desktops, Endpoint Management, NetScaler ADC, NetScaler Gateway, XenServer
VulDB
Mozilla Firefox up to 148 HTTP (Nessus ID 303907 / WID-SEC-2026-0850)
vuldb·2026-04-16·CVSS 9.8
CVE-2026-4700 [CRITICAL] Mozilla Firefox up to 148 HTTP (Nessus ID 303907 / WID-SEC-2026-0850)
A vulnerability classified as problematic was found in Mozilla Firefox up to 148. This issue affects some unknown processing of the component HTTP. Such manipulation leads to an unknown weakness.
This vulnerability is referenced as CVE-2026-4700. It is possible to launch the attack remotely. No exploit is available.
Upgrading the affected component is advised.
GHSA
GHSA-4pf4-jp4v-4g5c: Mitigation bypass in the Networking: HTTP component
ghsa_unreviewed·2026-03-24
CVE-2026-4700 [CRITICAL] CWE-288 GHSA-4pf4-jp4v-4g5c: Mitigation bypass in the Networking: HTTP component
Mitigation bypass in the Networking: HTTP component. This vulnerability affects Firefox < 149 and Firefox ESR < 140.9.
OSV
CVE-2026-4700: Mitigation bypass in the Networking: HTTP component
osv·2026-03-24·CVSS 9.8
CVE-2026-4700 [CRITICAL] CVE-2026-4700: Mitigation bypass in the Networking: HTTP component
Mitigation bypass in the Networking: HTTP component. This vulnerability affects Firefox < 149, Firefox ESR < 140.9, Thunderbird < 149, and Thunderbird < 140.9.
No detection rules found.
No public exploits indexed.
Bugzilla
CVE-2026-4700 firefox: thunderbird: Mitigation bypass in the Networking: HTTP component
bugzilla·2026-03-24·CVSS 9.8
CVE-2026-4700 [CRITICAL] CVE-2026-4700 firefox: thunderbird: Mitigation bypass in the Networking: HTTP component
CVE-2026-4700 firefox: thunderbird: Mitigation bypass in the Networking: HTTP component
Mitigation bypass in the Networking: HTTP component. This vulnerability affects Firefox < 149 and Firefox ESR < 140.9.
Discussion:
This issue has been addressed in the following products:
Red Hat Enterprise Linux 10
Via RHSA-2026:5931 https://access.redhat.com/errata/RHSA-2026:5931
---
This issue has been addressed in the following products:
Red Hat Enterprise Linux 9
Via RHSA-2026:5930 https://access.redhat.com/errata/RHSA-2026:5930
---
This issue has been addressed in the following products:
Red Hat Enterprise Linux 8
Via RHSA-2026:5932 https://access.redhat.com/errata/RHSA-2026:5932
---
This issue has been addressed in the following products:
Red Hat Enterprise Linux 9
Via RHSA-2026:
Wiz
CVE-2026-4700 Impact, Exploitability, and Mitigation Steps | Wiz
blogs_wiz·CVSS 7.5
CVE-2026-4700 [HIGH] CVE-2026-4700 Impact, Exploitability, and Mitigation Steps | Wiz
## CVE-2026-4700 :
NixOS vulnerability analysis and mitigation
Mitigation bypass in the Networking: HTTP component. This vulnerability affects Firefox < 149, Firefox ESR < 140.9, Thunderbird < 149, and Thunderbird < 140.9.
Source : NVD
## 9.8
Score
Published March 24, 2026
Severity CRITICAL
CNA Score 9.8
Affected Technologies
NixOS
Mozilla Firefox
Has Public Exploit No
Has CISA KEV Exploit No
CISA KEV Release Date N/A
CISA KEV Due Date N/A
Exploitation Probability Percentile (EPSS) 5.9
Exploitation Probability (EPSS) N/A
Affected packages and libraries
thunderbird
MozillaThunderbird-translations-common
Sources
AlmaLinux 8 Severity HIGH Has Fix Added at: Mar 31, 2026
AlmaLinux 9 Severity HIGH Has Fix Added at: Mar 31, 2026
Chainguard Has Fix Added at: Mar 29, 2026
https://bugzilla.mozilla.org/show_bug.cgi?id=2003766https://www.mozilla.org/security/advisories/mfsa2026-20/https://www.mozilla.org/security/advisories/mfsa2026-22/https://www.mozilla.org/security/advisories/mfsa2026-23/https://www.mozilla.org/security/advisories/mfsa2026-24/https://access.redhat.com/errata/RHSA-2026:5930https://access.redhat.com/errata/RHSA-2026:5931https://access.redhat.com/errata/RHSA-2026:5932https://access.redhat.com/errata/RHSA-2026:6188https://access.redhat.com/errata/RHSA-2026:6342https://access.redhat.com/errata/RHSA-2026:6917https://access.redhat.com/errata/RHSA-2026:7837https://access.redhat.com/errata/RHSA-2026:7838https://access.redhat.com/errata/RHSA-2026:7839https://access.redhat.com/errata/RHSA-2026:7840https://access.redhat.com/errata/RHSA-2026:7841https://access.redhat.com/errata/RHSA-2026:7842https://access.redhat.com/errata/RHSA-2026:7843https://access.redhat.com/errata/RHSA-2026:7845https://access.redhat.com/errata/RHSA-2026:7858https://access.redhat.com/errata/RHSA-2026:8284https://access.redhat.com/errata/RHSA-2026:8285https://access.redhat.com/errata/RHSA-2026:8286https://access.redhat.com/errata/RHSA-2026:8287https://access.redhat.com/errata/RHSA-2026:8288https://access.redhat.com/errata/RHSA-2026:8289https://access.redhat.com/errata/RHSA-2026:8290https://access.redhat.com/errata/RHSA-2026:8315https://access.redhat.com/errata/RHSA-2026:8427https://access.redhat.com/errata/RHSA-2026:8850https://access.redhat.com/security/cve/CVE-2026-4700https://bugzilla.redhat.com/show_bug.cgi?id=2450752https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4700.json
2026-03-24
Published