Mozilla Foundation Security Advisory 2026-21
Security Vulnerabilities fixed in Firefox ESR 115.34
- Announced
- March 24, 2026
- Impact
- high
- Products
- Firefox ESR
- Fixed in
-
- Firefox ESR 115.34
#CVE-2026-4684: Race condition, use-after-free in the Graphics: WebRender component
- Reporter
- Oskar L
- Impact
- high
References
#CVE-2026-4685: Incorrect boundary conditions in the Graphics: Canvas2D component
- Reporter
- Sajeeb Lohani
- Impact
- high
References
#CVE-2026-4686: Incorrect boundary conditions in the Graphics: Canvas2D component
- Reporter
- Sajeeb Lohani
- Impact
- high
References
#CVE-2026-4687: Sandbox escape due to incorrect boundary conditions in the Telemetry component
- Reporter
- Sajeeb Lohani
- Impact
- high
References
#CVE-2026-4689: Sandbox escape due to incorrect boundary conditions, integer overflow in the XPCOM component
- Reporter
- Sajeeb Lohani
- Impact
- high
References
#CVE-2026-4690: Sandbox escape due to incorrect boundary conditions, integer overflow in the XPCOM component
- Reporter
- Sajeeb Lohani
- Impact
- high
References
#CVE-2026-4691: Use-after-free in the CSS Parsing and Computation component
- Reporter
- Fabius Artrel
- Impact
- high
References
#CVE-2026-4692: Sandbox escape in the Responsive Design Mode component
- Reporter
- Tom Ritter
- Impact
- high
References
#CVE-2026-4693: Incorrect boundary conditions in the Audio/Video: Playback component
- Reporter
- Sajeeb Lohani
- Impact
- high
References
#CVE-2026-4694: Incorrect boundary conditions, integer overflow in the Graphics component
- Reporter
- Sajeeb Lohani
- Impact
- high
References
#CVE-2026-4696: Use-after-free in the Layout: Text and Fonts component
- Reporter
- Sota Wada
- Impact
- high
References
#CVE-2026-4698: JIT miscompilation in the JavaScript Engine: JIT component
- Reporter
- maxpl0it working with Trend Micro Zero Day Initiative
- Impact
- high
References
#CVE-2026-4699: Incorrect boundary conditions in the Layout: Text and Fonts component
- Reporter
- Matej Smycka
- Impact
- high
References
#CVE-2026-4706: Incorrect boundary conditions in the Graphics: Canvas2D component
- Reporter
- Jun Yang
- Impact
- moderate
References
#CVE-2026-4707: Incorrect boundary conditions in the Graphics: Canvas2D component
- Reporter
- Sajeeb Lohani
- Impact
- moderate
References
#CVE-2026-4709: Incorrect boundary conditions in the Audio/Video: GMP component
- Reporter
- Sajeeb Lohani
- Impact
- moderate
References
#CVE-2026-4721: Memory safety bugs fixed in Firefox ESR 115.34, Firefox ESR 140.9, Thunderbird ESR 140.9, Firefox 149 and Thunderbird 149
- Reporter
- Christian Holler, Timothy Nikkel, Tom Schuster and the Mozilla Fuzzing Team
- Impact
- high
Description
Memory safety bugs present in Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird ESR 140.8, Firefox 148 and Thunderbird 148. 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.