Hi! Author of the talk here.

Cheers!

On 9/14/26 21:28, Clemens Lang wrote: Hi, On 13. Sep 2026, at 02:44, Sam James <sam () gentoo org> wrote:

They also mention another vulnerability in the slides that is in the talk but I've not seen that yet. A PoC is available in their repo [3]. I see two potential vulnerabilities discussed in this talk:

(1) A RCE in gpgsm 2.4.9 when invoked as gpgsm --debug all --import bad.cert, with the bad.cert file at [1]. This is apparently a 0-day, as they say it was not reported to GnuPG. I’m not sure how widely used this code is, and how many users regularly call gpgsm --import with untrusted inputs. The researcher(s) say "if you're here to write a patch for the calc pop: sm/certcheck.c:634 lol” for this problem, which may be a pointer to debugging it.

(2) An integer underflow followed by a buffer overflow in libgcrypt’s RSASSA-PSS verification discussed in slides 38-45 of [2], fixed in libgcrypt commit 0d64fc2 [3] (also reported by somebody using Claude Code) released in (apparently) libgcrypt 1.12.3 without a CVE assigned. The researcher(s) claim this can be used for RCE from the S/MIME verifier and GnuPG with a 53-bit preimage attack (they don’t say which hash algorithm, but I wouldn’t be surprised if SHA-1 is sufficient).

Personally, I’m not all that interested in (1), but (2) seems to be in code that’s widely used, and there should probably be a CVE assigned for it so we can track fixes and backports.

[1]: https://git.gay/49016/gpg-fail-aftermath/src/branch/main/pocs/bad.cert [2]: https://git.gay/49016/gpg-fail-aftermath/src/branch/main/slides.pdf [3]: https://gitlab.com/redhat-crypto/libgcrypt/libgcrypt-mirror/-/commit/0d64fc2