From d8874dd38f78454dd3a760617ebe8d9aa9270649 Mon Sep 17 00:00:00 2001 From: NIIBE Yutaka Date: Fri, 10 Apr 2026 16:58:57 +0900 Subject: [PATCH] cipher:ecc: Fix decoding a point on Montgomery curve. * cipher/ecc-misc.c (_gcry_ecc_mont_decodepoint): Fix the padding mistake and add updating RAWMPILEN. -- Reported by Calif.io in collaboration with Claude and Anthropic Research. GnuPG-bug-id: 8211 Fixes-commit: bbe15758c893dbf546416c1a6bccdad1ab000ad7 Suggested-by: Bronson Yen Signed-off-by: NIIBE Yutaka CVE: CVE-2026-41989 Upstream-Status: Backport [https://github.com/gpg/libgcrypt/commit/2d3d732c9bf87cc10729f69678dd9e6862f99fa3] Signed-off-by: Leonid Iziumtsev --- cipher/ecc-misc.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/cipher/ecc-misc.c b/cipher/ecc-misc.c index 615b0df2..ab3799dc 100644 --- a/cipher/ecc-misc.c +++ b/cipher/ecc-misc.c @@ -438,7 +438,10 @@ _gcry_ecc_mont_decodepoint (gcry_mpi_t pk, mpi_ec_t ec, mpi_point_t result) *--p = *buf++; if (rawmpilen < nbytes) - memset (rawmpi + nbytes - rawmpilen, 0, nbytes - rawmpilen); + { + memset (rawmpi + rawmpilen, 0, nbytes - rawmpilen); + rawmpilen = nbytes; + } } else {