bug#63063: CVE-2021-36699 report

[Eli Zaretskii <eliz@gnu.org>]

> From: fuomag9 <fuo@fuo.fi>
> Date: Mon, 24 Apr 2023 21:27:34 +0000
> 
> I’m a security researcher and I’ve searched for a way to contact the emacs security team but I’ve not found any information online, so I’m reporting this issue here.
> I’ve discovered a buffer overflow in GNU Emacs 28.0.50 (at the time of writing the exploit still works on GNU Emacs 28.2)
> The issue is inside the --dump-file functionality of emacs, in particular dump_make_lv_from_reloc at pdumper.c:5239
> Attached to this email there's is payload used to make the vulnerability work (if emacs complains about a signature error you need to replace the hex bytes inside the payload with the expected one, since every emacs binary will expect a different signature).
> This issue has been assigned CVE-2021-36699 and thus I’m notifying you of this. (I do not think the emacs team is aware of this security issue)
> The POC is simple:
> Launch emacs --dump-file exploit, where exploit is a custom crafted emacs dump file

Please tell more about the buffer overflow: where does it happen in
the Emacs sources, which buffer overflows, and why.  I cannot find
these details in your report.

Also, the CVE ID seems to be incorrect: if I look it up, I get some
SQL related issue, not an Emacs issue.