Mozilla Firefox/Thunderbird Text Graphics UAF & Integer Overflow
CVE-2026-118009 Published on October 27, 2026
Integer overflow, use-after-free in the Graphics: Text component
Integer overflow, use-after-free in the Graphics: Text component. This vulnerability was fixed in Firefox 159 and Thunderbird 159.
Vulnerability Analysis
CVE-2026-118009 can be exploited with network access, requires user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to be very high.
Weakness Type
Integer Overflow or Wraparound
The software performs a calculation that can produce an integer overflow or wraparound, when the logic assumes that the resulting value will always be larger than the original value. This can introduce other weaknesses when the calculation is used for resource management or execution control. An integer overflow or wraparound occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may wrap to become a very small or negative number. While this may be intended behavior in circumstances that rely on wrapping, it can have security consequences if the wrap is unexpected. This is especially the case if the integer overflow can be triggered using user-supplied inputs. This becomes security-critical when the result is used to control looping, make a security decision, or determine the offset or size in behaviors such as memory allocation, copying, concatenation, etc.
Products Associated with CVE-2026-118009
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