[File] [SECURITY] Out-of-Bounds Read from Small .mgc File in apprentice.c (file-5.17)

[Christos Zoulas]

It was fixed in 2014 differently with he addition of check_buffer()

1.56         (christos 05-May-14):      if (pos + len > CDF_SEC_SIZE(h) * sst->sst_len) {

christos

> On Apr 1, 2026, at 11:20 AM, Kerwin <kerwinxia66001 at gmail.com> wrote:
> 
> Hi maintainers,
> 
> I am reporting an out-of-bounds read vulnerability in libmagic (file-5.17) where the minimum `.mgc` file size check in `apprentice_map()` (apprentice.c:2670) only requires 8 bytes, but the code subsequently reads `ptr[2]` and `ptr[3]` at offsets 8-15, causing an OOB read or SIGSEGV with any 8-15 byte `.mgc` file carrying a valid header.
> 
> Please find the detailed vulnerability report and proof-of-concept files attached.
> 
> Best regards
> 
> <POC.tar>-- 
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