From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-cve-announce@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@kernel.org>
Subject: CVE-2026-89698: nfsd: widen nfsd_genl_rqstp address fields to sockaddr_storage
Date: Fri, 11 Sep 2026 21:46:27 +0200 [thread overview]
Message-ID: <2026091155-CVE-2026-89698-0a54@gregkh> (raw)
From: Greg Kroah-Hartman <gregkh@kernel.org>
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
nfsd: widen nfsd_genl_rqstp address fields to sockaddr_storage
struct nfsd_genl_rqstp declares rq_daddr and rq_saddr as plain
"struct sockaddr" (16 bytes). When an IPv6 NFS client is connected,
nfsd_genl_rpc_status_compose_msg() casts these fields to
"struct sockaddr_in6 *" (28 bytes) and reads sin6_addr at offset 8..24,
which extends 8 bytes past the end of the 16-byte sockaddr field into
the adjacent rq_flags member. The 16-byte nla_put_in6_addr then ships 8
bytes of truncated IPv6 address followed by 8 bytes of rq_flags to
userspace via the NFSD_A_RPC_STATUS_SADDR6/DADDR6 netlink attributes.
This is reachable by any unprivileged process in the network namespace
because NFSD_CMD_RPC_STATUS_GET uses GENL_CMD_CAP_DUMP without
GENL_ADMIN_PERM.
Fix by widening rq_daddr and rq_saddr to struct sockaddr_storage so the
IPv6 casts operate within bounds, copying sizeof(struct sockaddr_storage)
bytes in the memcpy calls so the full address is captured, and
zero-initializing the genl_rqstp stack variable to prevent leaking
uninitialized tail bytes through netlink.
The Linux kernel CVE team has assigned CVE-2026-89698 to this issue.
Affected and fixed versions
===========================
Issue introduced in 6.7 with commit bd9d6a3efa9709e653aafbeb859289feccb8e70c and fixed in 6.18.51 with commit 03c512f22d3fbe7a3767d6df5e3d88b8e7c105e5
Issue introduced in 6.7 with commit bd9d6a3efa9709e653aafbeb859289feccb8e70c and fixed in 7.2.4 with commit dcb69ad0dafb4a24b825183bb94055d5be8a10bd
Issue introduced in 6.7 with commit bd9d6a3efa9709e653aafbeb859289feccb8e70c and fixed in 7.3-rc1 with commit a99d720ed2a5258564e5e9d5f39f3184a030d354
Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.
Unaffected versions might change over time as fixes are backported to
older supported kernel versions. The official CVE entry at
https://cve.org/CVERecord/?id=CVE-2026-89698
will be updated if fixes are backported, please check that for the most
up to date information about this issue.
Affected files
==============
The file(s) affected by this issue are:
fs/nfsd/nfsctl.c
Mitigation
==========
The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes. Individual
changes are never tested alone, but rather are part of a larger kernel
release. Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all. If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
https://git.kernel.org/stable/c/03c512f22d3fbe7a3767d6df5e3d88b8e7c105e5
https://git.kernel.org/stable/c/dcb69ad0dafb4a24b825183bb94055d5be8a10bd
https://git.kernel.org/stable/c/a99d720ed2a5258564e5e9d5f39f3184a030d354
reply other threads:[~2026-09-11 20:03 UTC|newest]
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