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 11CB5429CCF for ; Wed, 26 Aug 2026 14:37:25 +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=1787755047; cv=none; b=kI4K0v2b9ftygO2Q42wsO7F4/uyEzKOCsIrfQUcyBxz/7vJrCLULHVxbTM+f5JWjObaU3XGnvr2Xrg7SsnkqgiIT/bfFaVFZzXuihUvHW16JrQQRAzv7kHyowp+9HHDM23hLEz40bho7pEesd++LLI+PzQuQlo8V7xgHAnJGI4M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787755047; c=relaxed/simple; bh=V9dtDaHQxJ9lRhx8VPL6xWI2NEpi1A+cWUdDEJQyvyw=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=XVO7+gVUuQ/9dXXx03b3emnoXU7G/Yo/PqLmYkT6GUQE6unjiZ/cQx7Qfhld8Bfqg+hYom6U7uHxiBAYRqTS0R/k0FxtMDoid9XRUb0b/EysUrdxYB9MaJAmFX/KXQabgcjTnaw1hb9tCas0zr5qNC2hW8KXDCIIfhtXyN5iX1E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=aiZr22n9; 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="aiZr22n9" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A6C481F00A3A; Wed, 26 Aug 2026 14:37:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1787755045; bh=LSwCj1JIy85PnzzvfM3bwRK1JmpTRuXpO6pPwEYjqaQ=; h=From:To:Cc:Subject:Date:Reply-To; b=aiZr22n9Edd5JjjjRW5haKpjLrBFioDuqtP7oAbGGaqp7sgmG3LQtoPBV7MZv0TNZ ESI76Bm+8IN1qdRcZV/uffWM5pxFZDjLfdKrigdB+PpFTznfK+AnxhMBY7DY+l8k14 lnanab6X5V6DIxc3vQUZqSkD40wihWP+PotSLKqA= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-74735: l2tp: fix tunnel and session refcount leak on seq_file release Date: Wed, 26 Aug 2026 16:36:55 +0200 Message-ID: <2026082656-CVE-2026-74735-e7ef@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=2705; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=rPzsqKWj3Ta/kvdpLroagLwihmSBpdPvvtCLIbLvDVE=; b=owGbwMvMwCRo6H6F97bub03G02pJDFl9vzi0vsy7sjKnZ/WMEzt/qhtaa4j//e0zX7hHR11iI ctd3ZXLO2JZGASZGGTFFFm+bOM5ur/ikKKXoe1pmDmsTCBDGLg4BWAi2poMC7Zs7M7eFpdRevZF zp/ThewSwjYzbBlmszozrioLSW46lGoinnjej9VGiMsGAA== 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: l2tp: fix tunnel and session refcount leak on seq_file release In pppol2tp_proc_open() and l2tp_dfs_seq_open(), iteration state (pd->tunnel and pd->session) is kept in seq_file private data to allow iteration across multiple read() system calls. However, if userspace closes /proc/net/pppol2tp or /sys/kernel/debug/l2tp/tunnels before reading to end-of-file (EOF), any tunnel or session reference stored in pd->tunnel / pd->session is left un-dropped when seq_file private data is freed. Fix this by dropping any remaining pd->tunnel and pd->session references in pppol2tp_proc_release() and l2tp_dfs_seq_release() when closing the file. The Linux kernel CVE team has assigned CVE-2026-74735 to this issue. Affected and fixed versions =========================== Issue introduced in 4.17 with commit 0e0c3fee3a59a387aeecc4fca6f3a2e9615a5443 and fixed in 7.1.10 with commit ebe2774e956482dd3c70b8991f6f7654356339e6 Issue introduced in 4.17 with commit 0e0c3fee3a59a387aeecc4fca6f3a2e9615a5443 and fixed in 7.2 with commit 9006c116dd111d457bf5d074990210f70a4ad2c8 Issue introduced in 3.16.60 with commit f6104e9ae04462523c372928b1173766a771ef95 Issue introduced in 4.16.6 with commit 7f8e401f9e612df2a95c1ef76217c00181389bb5 Issue introduced in 3.16.60 with commit c712ed63e9b33d9a282fbd92ce25c64918c3129f Issue introduced in 4.16.6 with commit 9a8863e8a8def9d88583cd9c60db38a008e6b8cf 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-2026-74735 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/l2tp/l2tp_debugfs.c net/l2tp/l2tp_ppp.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/ebe2774e956482dd3c70b8991f6f7654356339e6 https://git.kernel.org/stable/c/9006c116dd111d457bf5d074990210f70a4ad2c8