From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 09BFF3C3F62 for ; Sat, 22 Aug 2026 15:37:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787413023; cv=none; b=XUnWx+2/L+zblz3GAFJWiEv5vUqfFSWgmMid8meL7/WO9O2BUzwBXJy7myh94JpOTGiGDOtGgxIzOSEY4gajIGQ5KSlMV4RrLB/vz0CkypbxZ7W5vzEwYKEy/pyLnu8lIkr/1qe1dUNMkccurA21iJB+2Rrs3DgJkxRTGc9WCms= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787413023; c=relaxed/simple; bh=qUwlTiWWNfC80jpEMidthYzPE+HG1IaOtaymlmbZr4Q=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=TnmCpUNIvRZ/12k3QpG7foLWnPx2nO0ukTfb++HMa7wAMVSP6rYT6HV1rRzIVG0OMK0y0zYypYlwYJGqFlK29SYAFVQUyaiD+cC4TadExlD6I3wcvVkCbyq+bPTptYR8omJOgG9eFJc3vYOMsLuvUaVJjOqX9O38BMC/kiidug8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ejLhthvv; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="ejLhthvv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5E9031F00A3A; Sat, 22 Aug 2026 15:37:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1787413021; bh=xoYC+Y3N/s3QmrEkCmiPDb+tTlSj+gKINaImI598ng0=; h=From:To:Cc:Subject:Date:Reply-To; b=ejLhthvvb2fdo+zUOWoq+Q6wMBRvotjFtLzL3nHFIMjPf51a5Hr1AKu/kDex0rs0+ iXxe7DMXeHhJ0921j+TjCbrwPlNYUE5vAgB6sCeEg7IEjK/ZRo31JLRIPZQVayZo5J VBULdSIASVRrYphvNArB0EW+vBejyiWnlmEsP8xA= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-74659: net: bridge: mrp: fix uninitialised bytes on the wire Date: Sat, 22 Aug 2026 17:32:23 +0200 Message-ID: <2026082227-CVE-2026-74659-16e5@gregkh> X-Mailer: git-send-email 2.55.0 Reply-To: , Precedence: bulk X-Mailing-List: linux-cve-announce@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3705; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=B11A/N3bjlo3Ig3y5ZzAtp+pKNqS8Qyyk3YPM2JVq8M=; b=owGbwMvMwCRo6H6F97bub03G02pJDFmdB87fOvr+FKv3/9+FfR51D+f5bn+hf5JF/qnb3wW/5 /TfKbXd3xHLwiDIxCArpsjyZRvP0f0VhxS9DG1Pw8xhZQIZwsDFKQAT0axlWLCxWm2dY5fczMd7 2/ruRwqdvyrz9TLDLOZfLKG5EqJX9KeuVbhSZ/bredLOGAA= X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 Content-Transfer-Encoding: 8bit From: Greg Kroah-Hartman Description =========== In the Linux kernel, the following vulnerability has been resolved: net: bridge: mrp: fix uninitialised bytes on the wire br_mrp_alloc_test_skb() builds MRP test frames on an skb from dev_alloc_skb(), which does not clear the linear data area. On the MRA ring-role branch the sub-option TLV header is appended with sub_tlv = skb_put(skb, sizeof(*sub_tlv)); sub_tlv->type = BR_MRP_SUB_TLV_HEADER_TEST_AUTO_MGR; so sub_tlv->length is never written, and the two trailing alignment bytes are appended with a bare skb_put() that does not clear them either. The neighbouring oui and sub_opt regions are explicitly zeroed, so three uninitialised bytes are left in every MRA MRP_Test frame that goes out. Put the sub-option TLV header and the alignment padding in a single skb_put_zero(), which clears both. The AUTO_MGR sub-TLV carries no payload, so the zeroed length field is already the value it should have. The Linux kernel CVE team has assigned CVE-2026-74659 to this issue. Affected and fixed versions =========================== Issue introduced in 5.14 with commit f7458934b0791c39a001e4d902fc3bf697b439b5 and fixed in 5.15.216 with commit 014c062d23c63ec77ef2cf17a0d9363c7441cc94 Issue introduced in 5.14 with commit f7458934b0791c39a001e4d902fc3bf697b439b5 and fixed in 6.1.183 with commit 7ebc23ff03668042e0b0e4034bb1518d36198d9e Issue introduced in 5.14 with commit f7458934b0791c39a001e4d902fc3bf697b439b5 and fixed in 6.6.152 with commit 06d58b8d2f053ced82e01efaeb6e7c82891eed58 Issue introduced in 5.14 with commit f7458934b0791c39a001e4d902fc3bf697b439b5 and fixed in 6.12.104 with commit a5e385eeb2d6dbbbdebfa050e67c34734ae12693 Issue introduced in 5.14 with commit f7458934b0791c39a001e4d902fc3bf697b439b5 and fixed in 6.18.45 with commit 5912cf1822fbe53ae275c147868740eb384a5d3e Issue introduced in 5.14 with commit f7458934b0791c39a001e4d902fc3bf697b439b5 and fixed in 7.1.9 with commit e08665218040f8e312abe40f74543186f3c2c941 Issue introduced in 5.14 with commit f7458934b0791c39a001e4d902fc3bf697b439b5 and fixed in 7.2 with commit 63488dba65ef91373ef616575b32eb0eb21459f4 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-2026-74659 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: net/bridge/br_mrp.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/014c062d23c63ec77ef2cf17a0d9363c7441cc94 https://git.kernel.org/stable/c/7ebc23ff03668042e0b0e4034bb1518d36198d9e https://git.kernel.org/stable/c/06d58b8d2f053ced82e01efaeb6e7c82891eed58 https://git.kernel.org/stable/c/a5e385eeb2d6dbbbdebfa050e67c34734ae12693 https://git.kernel.org/stable/c/5912cf1822fbe53ae275c147868740eb384a5d3e https://git.kernel.org/stable/c/e08665218040f8e312abe40f74543186f3c2c941 https://git.kernel.org/stable/c/63488dba65ef91373ef616575b32eb0eb21459f4