From nobody Tue Jun 9 23:13:05 2026 X-Original-To: freebsd-announce@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 4gZl7k0W28z6gprM for ; Tue, 09 Jun 2026 23:13:06 +0000 (UTC) (envelope-from security-advisories@freebsd.org) Received: from freefall.freebsd.org (freefall.freebsd.org [96.47.72.132]) (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 4gZl7j3hDMz3NlR; Tue, 09 Jun 2026 23:13:05 +0000 (UTC) (envelope-from security-advisories@freebsd.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1781046785; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc; bh=tivrbYmly80Hn94BoaLH7ruKqvQRduljtiGoPnKHrOQ=; b=Pv+nmMVeORaQpEtJaxNdoNrQQlPScsJjDcqVemGoTLApLV/lhP/ds9wbI8RsD1HhufKULc NIMSrmEFq5JJfhFlEwVLVY9KIKIas1CJ0wuiWV+5itQvNKZ2m/+SmO3thJRzwTP32fAIxX h6XrWQILIKUUi+wJ6fqWlOIsdwnb53Wb3W7mB8c9aVHx9ZE6cYiCk6NPGkYyJsgpYVKwMd QAZ4gnw3ySXpj+nIIQGpvHsYYEqYvLmte7CA0Q3RLTcoPerOtdal5FuxtOs/fzZ1+SeDV7 UAXyfJ3rlsfnC9FxzTduTc/KDqHbrovoUrVCFwiUTXKQAyHD33pbkk4ax1tVQQ== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1781046785; a=rsa-sha256; cv=none; b=PrJkb6zdA09L8B0J2dd41FqYzXVuZYChdLhxYHmaihROkUBm3JgKbj1NVu7p89UajQwvpr KHGbTXBJE+iAfq8htGmjsKNjk7sU6x0oJWck4jOSmgqz1d46Tr/8vTcjMnMZomYuOmDzEu TRfXhzZVGMdcOJuSnA6jPUsBPBjhDuvmfWYWeRtpuWG2cmp0BDIsImo+rQNzjm4cXGlkZD 2OzYdB20EGEyx1c1VV68m9TVAv159X59QxV4hyMfqbPWO+G6QUsTu1Tv9OI31RKh05Y1Z+ 2x66VmAQkh3BStKyqr2uqD2R+0PDQKLshumJl+Vit7EWqABrS2Noy1QLXGF5qw== 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=1781046785; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc; bh=tivrbYmly80Hn94BoaLH7ruKqvQRduljtiGoPnKHrOQ=; b=RzVRZqh7EhymEzAT3aXa64AcT0WozjDIBjSORVsGjqe6pcPjxFvVm5jDdm9LjK7yw/LJZo JeI+kMXiH0YIEy0LHxCGgTI4uucqnuZ51csV2aiQcAejG+HagPvnHLRigSxMGiLhDUqavY UbHrgDTUrIv8QALZV7gHrHpaR57M/MmGS+5IPow+ScNK9AMyJFY2Gywv9aa6kZwR+zZFo/ VVUgaYDyOCwhuNvFnO+a28l1l9VcZJLGxwbos4tDiQpp/nmG3TNt0kGkpjaCh+Dx95C/Ha S5S4agQGwuLe4IHCcVUwA9V9PpoAWw18SpkEu1etTVYYnWU/qZ+av2cLqHHSPQ== Received: by freefall.freebsd.org (Postfix, from userid 945) id 6CD381FCB8; Tue, 09 Jun 2026 23:13:05 +0000 (UTC) From: FreeBSD Security Advisories To: FreeBSD Security Advisories Subject: FreeBSD Security Advisory FreeBSD-SA-26:25.thr Reply-To: freebsd-security@freebsd.org Precedence: bulk Message-Id: <20260609231305.6CD381FCB8@freefall.freebsd.org> Date: Tue, 09 Jun 2026 23:13:05 +0000 (UTC) List-Id: Project Announcements [moderated] List-Archive: https://lists.freebsd.org/archives/freebsd-announce List-Help: List-Post: List-Subscribe: List-Unsubscribe: X-BeenThere: freebsd-announce@freebsd.org Sender: owner-freebsd-announce@FreeBSD.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 ============================================================================= FreeBSD-SA-26:25.thr Security Advisory The FreeBSD Project Topic: Missing permission check in thr_kill2(2) Category: core Module: thr Announced: 2026-06-09 Credits: Yuxiang Yang, Yizhou Zhao, Ao Wang, Xuewei Feng, Qi Li, and Ke Xu from Tsinghua University using GLM-5.1 from Z.ai Credits: Igor Gabriel Sousa e Souza Affects: All supported versions of FreeBSD Corrected: 2026-06-09 19:17:27 UTC (stable/15, 15.1-STABLE) 2026-06-09 19:20:05 UTC (releng/15.1, 15.1-RC3-p1) 2026-06-09 19:19:42 UTC (releng/15.0, 15.0-RELEASE-p10) 2026-06-09 19:17:45 UTC (stable/14, 14.4-STABLE) 2026-06-09 19:19:04 UTC (releng/14.4, 14.4-RELEASE-p6) 2026-06-09 19:18:34 UTC (releng/14.3, 14.3-RELEASE-p15) CVE Name: CVE-2026-45256 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 The thr_kill2(2) system call delivers a signal to a specific thread of a process identified by its process and thread IDs. As with kill(2), the kernel verifies that the calling process is permitted to signal the target before the signal is delivered. II. Problem Description When used to deliver a signal to a specific thread, thr_kill2(2) called p_cansignal() to determine whether the operation was permitted but did not check the result before delivering the signal. The signal was sent even when the permission check failed. The system call returned the resulting error to the caller, but by then the signal had already been delivered. III. Impact The missing check allows an unprivileged local user who knows or can guess a target's process and thread IDs to send any signal to a process they would not normally be permitted to signal, including processes owned by other users or by root. The same check enforces jail boundaries, so a jailed process can signal processes on the host or in other jails. Thread IDs are allocated globally and sequentially, and so can be discovered by brute force with no visibility into the target. An attacker can stop or terminate arbitrary processes, including critical system daemons, resulting in a Denial of Service (DoS). 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. # fetch https://security.FreeBSD.org/patches/SA-26:25/thr.patch # fetch https://security.FreeBSD.org/patches/SA-26:25/thr.patch.asc # gpg --verify thr.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/ afa0c67a1ba3 stable/15-n283881 releng/15.1/ 068168fefd4b releng/15.1-n283549 releng/15.0/ 6f6c7b996719 releng/15.0-n281051 stable/14/ 72ad7baa99c7 stable/14-n274310 releng/14.4/ 31f6086db8fe releng/14.4-n273713 releng/14.3/ fa5581c379fe releng/14.3-n271513 - ------------------------------------------------------------------------- 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----- iQJPBAEBCgA5FiEEthUnfoEIffdcgYM7bljekB8AGu8FAmooiUobFIAAAAAABAAO bWFudTIsMi41KzEuMTIsMCwzAAoJEG5Y3pAfABrvHNUQAMEmYLwDsVIj73SAnWE4 PN3KAVFvybeK4R4xYPiwPDtOrdV6HEb4G9O9VgZAomMzE9U7OIZVbXSjKdnEc4Ud /54Kg0VlURUCUxncndeBVnT56IzXf9uuT1HuAcSoyN2dDZedAGFbtIrg2YJvPyWL oOe1TyRrj03sP8VnznCZZsPYIqUb7UopdFHaVv2qONdlC0OSnODWiqeRJ8Z38tCd 918AbxTarEKwv5Qx8kV2mvvXIAaK1f6K7l2KqFGdp8HCf5C/plBd7vv6SEVvQhDj 8D6c1Syc/rUTkn6bmeLFinaPxK7OB1oS/Z+7DwJrjlusAhSKbBFcesE2hHYzxEhP 8rmevDJPMNZbouvuC4aJeDSKvGd5eUL+5Rt/EIijBsrlzZv1g/glllbTc/7+g3um aGP9c4BCDUJVjWxui5ACqR9pe2LWQwDtA7YbukXZqkH0M2OroxLRWWCyOLrAlela Eilf64XI6KliSMR+rAL6dmPLxFXVMpJXRKxJmUK3FXDi+Vm0bGaeRwCz49Ts+6XV oU7MRQG/F1w+lZRkS2XQ6YJTv4DBiDAofl7i0Rcjlq1JbWxBjpF8ArZX5VqSSi1y bOkum8QekuU/sbBIij7JyiEPx2r0ICm/pGXDYnxYuwd0+48orpu9uB6M0gKYEe6D mYgtjqeBtUCJwPKOzr36faXQ =rFeT -----END PGP SIGNATURE-----