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Message-Id: <DC806F2C-6179-4146-9B6E-A13E7FE67861@redhat.com>
Date: Mon, 14 Sep 2026 21:28:03 +0200
From: Clemens Lang <cllang@...hat.com>
To: oss-security@...ts.openwall.com
Cc: "Lexi Groves (49016)" <contact@....fail>,
Werner Koch <wk@...pg.org>
Subject: Re: Retrospective by 'gpg.fail' authors
Hi,
> On 13. Sep 2026, at 02:44, Sam James <sam@...too.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
--
Clemens Lang
RHEL Crypto Team
Red Hat
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