From nobody Tue Jun 9 23:13:35 2026 X-Original-To: freebsd-security@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4gZl8H3swZz6gprM for ; Tue, 09 Jun 2026 23:13:35 +0000 (UTC) (envelope-from security-advisories@freebsd.org) Received: from freefall.freebsd.org (freefall.freebsd.org [IPv6:2610:1c1:1:6074::16:84]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "freefall.freebsd.org", Issuer "R12" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 4gZl8H2MNCz3Pf4; Tue, 09 Jun 2026 23:13:35 +0000 (UTC) (envelope-from security-advisories@freebsd.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1781046815; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc; bh=ijLis1D3PnaXPGRkb/gipWkcZRP3C7Z8qoyPSL/kqfU=; b=G4My2xo2uCcTRVgOLmTcFyW3nGcRmW/1BP/DhBKSWrujtRwjzhIwCtA4QCrlyUzBN1Xott npot2LOFQBZfIaDqO63xWANo75VUySm1H6VN/CWbJMXeJF1/rr1hbQuWJVgt0fgiXVCIFm WS9zUh2PPfnySxcN8Yp/nFK1YzC1EFqvDOptVZlnVMI9V/rd2QuEuQHAf48zooRMaWUuPb +Xw48ALaxDWVi57M73LiCXvmuZLWURcDW/dkE5ParzHlQ6+DEG/ncJKkJniBlUz59d5eSz wx0DSONQL6IVb/FnheNedzN/DaxDEDDxVpBBt5PslYWedmTvQkqcfn1oQzLcyg== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1781046815; a=rsa-sha256; cv=none; b=NI0SAJ3zxZbEm7bvJBHleL4uMX/qsqUTQdJofkGnZNxjf+PT2PqwfsQCG2mwpvjh8OWT7V G5lPV4pRLhkhrUwbz7AZLz/ExiD9l4cvrFJI+E9mR17jzHBDtkFuXnn8YhuCf00quMT7Eu Ka/6e++6jzrFKPbEc780xetc4WUr1ze6+l5r3OchpCLUZY/kABev+W8ayDBYjAhNDIuKkL 1dDnfkXGVfMMNpgaGY363d3o6TrnA6psM34mZKsVc70k2EzePOYXzssOAp49INmAXmjBdz 0oIFYe/n1Wf/u4OrefXbUeK86mSPYxfiuq3ewvrDU4bEZtGtJRi2Ay0BFYsU1A== ARC-Authentication-Results: i=1; mx1.freebsd.org; none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1781046815; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc; bh=ijLis1D3PnaXPGRkb/gipWkcZRP3C7Z8qoyPSL/kqfU=; b=Eoq0YuKuCH4dG1PjFRLBoiTcfd5RXIm/VDeYp66HGiIq++8HMjmtKGc/6F+63QpYKcFnkC Ry2Y9JQbCHfmu+DGwMPxNQcmyxUJeAJicF4CU3OyyFDv4Eck5iwgxZmdqb46tCl81/TqtR oFh3PW8i4qZs9pEKv+QqyDO36kU3QtxqdYRqbKMeQjVJBfzHA9UsRUKJolaWTDTdqcWzAi g1KVKVg+WVxyldrvTvV05j33niw5up4O2eZpz/tLDJk/UT1QYQlKy6aL4EIFwKAa1jIsvA o85jrC+xuV1aC3m+sVeXeBg7T2+tlJmGak+ZDtz6O9lh/XxidzXXrDujG2XsCg== Received: by freefall.freebsd.org (Postfix, from userid 945) id 391411FC55; Tue, 09 Jun 2026 23:13:35 +0000 (UTC) From: FreeBSD Security Advisories To: FreeBSD Security Advisories Subject: FreeBSD Security Advisory FreeBSD-SA-26:29.ip6_multicast Reply-To: freebsd-security@freebsd.org Precedence: bulk Message-Id: <20260609231335.391411FC55@freefall.freebsd.org> Date: Tue, 09 Jun 2026 23:13:35 +0000 (UTC) List-Id: Security issues List-Archive: https://lists.freebsd.org/archives/freebsd-security List-Help: List-Post: List-Subscribe: List-Unsubscribe: X-BeenThere: freebsd-security@freebsd.org Sender: owner-freebsd-security@FreeBSD.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 ============================================================================= FreeBSD-SA-26:29.ip6_multicast Security Advisory The FreeBSD Project Topic: Use-after-free bug in the IPV6_MSFILTER socket option handler Category: core Module: ip6_multicast Announced: 2026-06-09 Credits: Andrew Griffiths at Calif.io Credits: Maik Münch Affects: All supported versions of FreeBSD Corrected: 2026-06-09 19:17:32 UTC (stable/15, 15.1-STABLE) 2026-06-09 19:20:10 UTC (releng/15.1, 15.1-RC3-p1) 2026-06-09 19:19:47 UTC (releng/15.0, 15.0-RELEASE-p10) 2026-06-09 19:17:49 UTC (stable/14, 14.4-STABLE) 2026-06-09 19:19:09 UTC (releng/14.4, 14.4-RELEASE-p6) 2026-06-09 19:18:39 UTC (releng/14.3, 14.3-RELEASE-p15) CVE Name: CVE-2026-49412 This vulnerability was independently reported by multiple parties prior to publication. For general information regarding FreeBSD Security Advisories, including descriptions of the fields above, security branches, and the following sections, please visit . I. Background FreeBSD's IPv6 multicast subsystem supports source-specific multicast filtering via the IPV6_MSFILTER socket option. This option, set with setsockopt(2), allows applications to specify which remote hosts are permitted to send to a joined multicast group. II. Problem Description The kernel handler for IPV6_MSFILTER dropped a serializing lock in order to copy the source-filter list from userspace, then reacquired the lock. During this window another thread could free the multicast filter structure, leaving the handler with a stale pointer to freed memory. III. Impact An unprivileged local user can exploit this use-after-free to escalate privileges. IV. Workaround No workaround is available. V. Solution Upgrade your vulnerable system to a supported FreeBSD stable or release / security branch (releng) dated after the correction date, and reboot the system. Perform one of the following: 1) To update your vulnerable system installed from base system packages: Systems running a 15.0-RELEASE version of FreeBSD on the amd64 or arm64 platforms, which were installed using base system packages, can be updated via the pkg(8) utility: # pkg upgrade -r FreeBSD-base # shutdown -r +10min "Rebooting for a security update" 2) To update your vulnerable system installed from binary distribution sets: Systems running a RELEASE version of FreeBSD on the amd64 or arm64 platforms which were not installed using base system packages can be updated via the freebsd-update(8) utility: # freebsd-update fetch # freebsd-update install # shutdown -r +10min "Rebooting for a security update" 3) To update your vulnerable system via a source code patch: The following patches have been verified to apply to the applicable FreeBSD release branches. a) Download the relevant patch from the location below, and verify the detached PGP signature using your PGP utility. [FreeBSD 15.1] # fetch https://security.FreeBSD.org/patches/SA-26:29/ip6_multicast-15.1.patch # fetch https://security.FreeBSD.org/patches/SA-26:29/ip6_multicast-15.1.patch.asc # gpg --verify ip6_multicast-15.1.patch.asc [FreeBSD 15.0] # fetch https://security.FreeBSD.org/patches/SA-26:29/ip6_multicast-15.0.patch # fetch https://security.FreeBSD.org/patches/SA-26:29/ip6_multicast-15.0.patch.asc # gpg --verify ip6_multicast-15.0.patch.asc [FreeBSD 14.x] # fetch https://security.FreeBSD.org/patches/SA-26:29/ip6_multicast-14.patch # fetch https://security.FreeBSD.org/patches/SA-26:29/ip6_multicast-14.patch.asc # gpg --verify ip6_multicast-14.patch.asc b) Apply the patch. Execute the following commands as root: # cd /usr/src # patch < /path/to/patch c) Recompile your kernel as described in and reboot the system. VI. Correction details This issue is corrected as of the corresponding Git commit hash in the following stable and release branches: Branch/path Hash Revision - ------------------------------------------------------------------------- stable/15/ ce2b95932ec2 stable/15-n283885 releng/15.1/ 3d80e4aec3c1 releng/15.1-n283554 releng/15.0/ ed4692b8226e releng/15.0-n281056 stable/14/ 522182827ea1 stable/14-n274314 releng/14.4/ a7062a6de005 releng/14.4-n273718 releng/14.3/ e6859453de61 releng/14.3-n271518 - ------------------------------------------------------------------------- Run the following command to see which files were modified by a particular commit: # git show --stat Or visit the following URL, replacing NNNNNN with the hash: To determine the commit count in a working tree (for comparison against nNNNNNN in the table above), run: # git rev-list --count --first-parent HEAD VII. References The latest revision of this advisory is available at -----BEGIN PGP SIGNATURE----- iQJPBAEBCgA5FiEEthUnfoEIffdcgYM7bljekB8AGu8FAmoolxMbFIAAAAAABAAO bWFudTIsMi41KzEuMTIsMCwzAAoJEG5Y3pAfABrv7wUP/30Oo0Z61lnOg4P7VBtk K6bljtcQ0SoiW++eWtX2TFHqCrcNS0qPSxQFVKDkkUf2Wx9M/zfkhUWnTpAwbQdB m+8bUN8CGEjhvAihfKgCAQZGSqcVq8A2km+JgFpc9ehZ3RjnjFQ0DYZTOh1goZiQ TPsWf8NwKQfed1LhQcDLp0hw7R4//wBICfluzFvLDqPG7TtcAvcJN04jrmd6XCaY zddGXzWvrPGuRPY7/xgiwg26B4yK/OwzOJ0uBzBGLGzkuUKJjZgzot3kVy7WmTVw iWKRChKQiakM+hkf/xi3CZiyUVGdlxd5GDWxJ8HvaNkYtk/iRzvalVMkSrZNdnaJ rVMCmt0d+PxD6+2xORikqn+FiYNc+5gUB64O9t74+L1/XMtM0IWz/g2Zs66qding 0gABccQX5217YvZK8fubpihEPF7NCNblfikIZbdWYwmMk7azQ93tTO0ySCpuzIVX +OJWR2QRrz004ohwgl9peBfcDEvbxN5KEovVDt/QTZ1JGKQ8AeiJCd7JZsNP1zMw SAOof6EyOEzuilT8JDmOXhnXptOVwCG470bD9rYL3O6apFfcWqFVh+5njEaGMrBf 8W381AnPDmkEROxj3fzJkM7Xik64aJrHgLGFuHZAQ1Yjpr+SrJRKcdHx295qFp4a m+8DOaIYeHuOhRTGRLMubJIj =uFAo -----END PGP SIGNATURE-----