https://gitlab.com/sequoia-pgp/sequoia/-/commit/b59886e5e7bdf7169ed330f309a6633d131776e5
which was first released with rust-sequoia-openpgp 2.1.0
describes (and then fixes) the following problem:

openpgp: Fix an underflow in aes_key_unwrap.

The `aes_key_unwrap` function would panic if passed a ciphertext
that was too short.  In a debug build, it would panic due to a
subtraction underflow.  In a release build, it would use the small
negative quantity to allocate a vector.  Since the allocator
expects an unsigned quantity, the negative value would be
interpreted as a huge allocation.  The allocator would then fail
to allocate the memory and panic.

An attacker could trigger this panic by sending a victim an
encrypted message whose PKESK or SKESK packet has been specially
modified.  When the victim decrypts the message, the program would
crash.

Reported-by: Jan Różański.

hi Holger,

CVE-2025-67897 has been assigned for this issue.

Regards,
Salvatore

We believe that the bug you reported is fixed in the latest version of
rust-sequoia-openpgp, which is due to be installed in the Debian FTP archive.

A summary of the changes between this version and the previous one is
attached.

Thank you for reporting the bug, which will now be closed.  If you
have further comments please address them to 1122582@bugs.debian.org,
and the maintainer will reopen the bug report if appropriate.

Debian distribution maintenance software
pp.
Holger Levsen <holger@debian.org> (supplier of updated rust-sequoia-openpgp package)

(This message was generated automatically at their request; if you
believe that there is a problem with it please contact the archive
administrators by mailing ftpmaster@ftp-master.debian.org)
Format: 1.8
Date: Mon, 22 Dec 2025 16:27:34 +0100
Source: rust-sequoia-openpgp
Architecture: source
Version: 2.0.0-2+deb13u1
Distribution: trixie
Urgency: medium
Maintainer: Debian Rust Maintainers <pkg-rust-maintainers@alioth-lists.debian.net>
Changed-By: Holger Levsen <holger@debian.org>
Closes: 1122582
Changes:
 rust-sequoia-openpgp (2.0.0-2+deb13u1) trixie; urgency=medium
 .
   * Add upstream commit b59886e5 (via debian/patches, edited to apply cleanly)
     to fix an underflow in aes_key_unwrap / CVE-2025-67897 to prevent DOS
     (crash) via special crafted encrypted messages. Closes: #1122582.
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Checksums-Sha256:
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 817b79e4f22a69844a0a4e44e4154ba8d4f85ccd488f563dd67d08a8d350eb74 9908 rust-sequoia-openpgp_2.0.0-2+deb13u1.debian.tar.xz
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Files:
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