[File] [SECURITY] Integer Overflow in .mgc File nmagic Validation Leading to SIGSEGV (file-5.17)

[Christos Zoulas]

Added validation as suggested.

Thanks,
christos

> On Apr 1, 2026, at 11:16 AM, Kerwin <kerwinxia66001 at gmail.com> wrote:
> 
> Hi maintainers,
> 
> I am reporting an integer overflow vulnerability in libmagic (file-5.17) where a crafted `.mgc` file exploits a `uint32_t` wraparound in the `nmagic` sum validation in `apprentice_map()` (apprentice.c:2716-2733), causing an out-of-bounds pointer and a SIGSEGV crash on the next access.
> 
> Please find the detailed vulnerability report and proof-of-concept files attached.
> 
> Best regards
> 
> <POC.tar>-- 
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