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 0EE483EC685 for ; Sat, 15 Aug 2026 12:29:31 +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=1786796972; cv=none; b=XRH7wZK+PPbmZ4uyKyixDXdEaUSrpk33lszFwwpvsU6gQUS+Lw1Qzf5nz6kRBO7m06ohWriPrI/gBaMLZz5FBLShYf06pOPNgiFZAFVwNWlkIx1zcScq2XbsmkCutuw2DbDHK3dBttm4Al2sFTZHClphsBOVx+B33otl/mEyBAs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786796972; c=relaxed/simple; bh=7ApJAMWqWOQCr40FSJL7rP/+1qIHoKsNckXhOqasV9k=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=J5wIsmcE8W6MHPdkMcX9ahh1NIuCkAn7/u7ZGHkWkCUfGWWkAGTlrFvFAgyCRgDdTrjoShG7ri2WU5Thg25MG4fiCLlNYvc7zlxMD+QUcXB5y8nRPYt/sObEMA/u1QLvHRJkMVepYuHyM1YKk66R4Ei+izjqk8iq+H2p6rE+hbM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=l7V1NHms; 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="l7V1NHms" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 65E1D1F000E9; Sat, 15 Aug 2026 12:29:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786796970; bh=BdY6kLKd5o6rbPa4YTSThx2KF+SSpCqO2m4Qhaot0ms=; h=From:To:Cc:Subject:Date:Reply-To; b=l7V1NHms+PZdvs2F9gwXqjy/xjZ3EeQqh7HeByhHBV1NKdEC9juEj1hXa0qSCjzvD /NcpExS9rTqgPLFZL9rcueyIhTO7IKikZwSgcrDpr7G7swYAYeepGPZSA32yIVWkWU tdQDS3lbINtZYIJShOFPSShEQFYcq9Zt86WwhnR0= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-74485: binfmt_misc: reject a flag character as the field delimiter Date: Sat, 15 Aug 2026 21:26:06 +0900 Message-ID: <2026081537-CVE-2026-74485-002e@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=4107; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=FYanyWPElmJxXrg0FUY6ltwI2+yP7Zctp4doC2vcDEw=; b=owGbwMvMwCRo6H6F97bub03G02pJDFkNUQerNn7oZTe7Ib5H/dAdVs3P3AtclSbKt33Ned8/5 W3mt4SkjlgWBkEmBlkxRZYv23iO7q84pOhlaHsaZg4rE8gQBi5OAZjInFCG+fEpP3Va8tc2eibP /BfNZMkfv049lWHBhQf5tlcLez9fDGNgC47VarvAfFkSAA== 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: binfmt_misc: reject a flag character as the field delimiter The registration string starts with a user chosen delimiter that separates the individual fields. So that the field parsers terminate even on a truncated string create_entry() pads the buffer with that same delimiter: memset(buf + count, del, 8); Most fields are scanned for the delimiter with strchr()/scanarg() and happily stop on the padding. The flags field is different: instead of scanning for the delimiter check_special_flags() consumes the flag characters 'P', 'O', 'C' and 'F' and stops at the first byte that is none of them, relying on the trailing delimiter to end the scan. If the delimiter is itself a flag character the padding no longer acts as a terminator. The scan swallows all eight padding bytes and keeps reading past the end of the allocation until it hits a byte that is not a flag character. For example registering PaPEPPxPPiP with 'P' as the delimiter (name "a", type extension, magic "x", interpreter "i", empty flags) leaves the flag scan running off the end of the buffer. The registration is rejected in the end because the parser does not stop exactly at buf + count, but only after the out of bounds read has already happened. With an unlucky allocation layout the scan can walk into an unmapped page; under KASAN it is reported as a slab out of bounds read. binfmt_misc mounts are available to unprivileged users in a user namespace so the read is reachable without privileges. Reject a delimiter that is one of the flag characters up front. Such a registration was always rejected anyway, only after the out of bounds read, so no valid registration string changes meaning. The Linux kernel CVE team has assigned CVE-2026-74485 to this issue. Affected and fixed versions =========================== Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.6.151 with commit 1819f82dee766c58295ecaacdac02cdf6837d7a4 Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.12.103 with commit 1853e95c9bfe69ef1dd862b3f551e68f4a1b76cc Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.18.44 with commit 840bb9c49c3e75fb32b593d67ab32f6b77122262 Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 7.1.8 with commit 9a2d87db3898b5993b64fd258d0334e0eba9ee0d Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 7.2-rc6 with commit 8e85d50ba1117fd446bf9a250bd8a97d48384bdc 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-2026-74485 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/binfmt_misc.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/1819f82dee766c58295ecaacdac02cdf6837d7a4 https://git.kernel.org/stable/c/1853e95c9bfe69ef1dd862b3f551e68f4a1b76cc https://git.kernel.org/stable/c/840bb9c49c3e75fb32b593d67ab32f6b77122262 https://git.kernel.org/stable/c/9a2d87db3898b5993b64fd258d0334e0eba9ee0d https://git.kernel.org/stable/c/8e85d50ba1117fd446bf9a250bd8a97d48384bdc