From nobody Tue Apr 21 17:02:21 2026 X-Original-To: freebsd-security-notifications@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 4g0TDY5MFbz6YWqB for ; Tue, 21 Apr 2026 17:02:21 +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 "R13" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 4g0TDY3pTlz3wc3; Tue, 21 Apr 2026 17:02:21 +0000 (UTC) (envelope-from security-advisories@freebsd.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1776790941; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc; bh=LSS1CObFUi23kYBIU5BBPmZnSyvzdqW5ySLkd7kgUeE=; b=fXtwOBcoFflplxkBt2bwb/Ns2fdW2GmlRSVDoJR4bmqei4ZRGiK8tJr2ma8JJ2GmIKRngO e2tjDwBTZqt/xetxuHvW/RcFwjTfb8aRQa8h7c8WcQTBXcBtN8fUq+6IFKkICj6Xut5BjU qZkjKCR2syIK2V9U2/1m5/9wEemnJqWy2XHIkRPwZ2A8GMc8T/Nlcw2VSU3VvXbUvkBodq EYDNzYyA4yJth1N/Oo+QfGcKtb8o1fNwA8o1TrvViz5rAYlvY9FrbkN832UnkdWqUovRg7 1l/hYA8wzk+oKX2yphk38T5tXisxD5JbLb76nFwW5V1HM8zqpA8Gf7gzDefizw== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1776790941; a=rsa-sha256; cv=none; b=vBKaAEchMOfj0sYSnoMyT0Ux9djNzwe3z0+H8bPwAQyPBH4Gvtk+r8uRyd2oNASa972PsO 6saNAFwICTHjuA4fsuyQwuVQnTClWjPBvIaxlQh72/nbdlSX81D5jguWosRv1hrZyzi5gi 1nyJ7QeSE3s4M+eIuLjA4KHKHKDjhhviFTIhBU4L0osSqzQ8QICxm90qa54PU5Y9n2scZQ f3D98lIG5+w5bZRDCChKmHtN6bmuoYZu1/mFRZXIVovPHmxcUwISJxHlunuwLPLe1ANwlz gwfqKLY9mtelO5HhOF4BmXCx6rKjx3WLcEcP3OgV3ioTY+95PMMxqG8RJaEzUA== 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=1776790941; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc; bh=LSS1CObFUi23kYBIU5BBPmZnSyvzdqW5ySLkd7kgUeE=; b=j3pn38QrAj1k/dtfJvv5PFhM+0G1OQ7rKIyHlRb5D3dIjjvwzUoYKAtM72/W23aSFTVdua j8Aif2MIg7S2WMKl8USZK1FY9BGTx+9M93Sdlr+AriXimkcTAy0GbP4nVVHEvMmc2fHXmH SbjJJ555MtfWLDf+rb7y/BJ+R5L1fTZUKKo6aYiGulsSzkxqAfD0cUPtMjPKHp9Hb3zzdZ FE5EfCTOm83QqQ1nL6CObW+v4zXIE6eCh6LZbtWpiMIgg0jO8mR/+X1MVnGhQ5WNZE9jYV Hcq6s3ncxZANQBSKgwsExYvg/1QLYOXbx3i98su4jnBO4nGVKwZmT9w2/kgJQQ== Received: by freefall.freebsd.org (Postfix, from userid 945) id 7785A1FBE3; Tue, 21 Apr 2026 17:02:21 +0000 (UTC) From: FreeBSD Security Advisories To: FreeBSD Security Advisories Subject: FreeBSD Security Advisory FreeBSD-SA-26:10.tty Reply-To: freebsd-security@freebsd.org Precedence: bulk Message-Id: <20260421170221.7785A1FBE3@freefall.freebsd.org> Date: Tue, 21 Apr 2026 17:02:21 +0000 (UTC) List-Id: Moderated Security Notifications [moderated, low volume] List-Archive: https://lists.freebsd.org/archives/freebsd-security-notifications List-Help: List-Post: List-Subscribe: List-Unsubscribe: X-BeenThere: freebsd-security-notifications@freebsd.org Sender: owner-freebsd-security-notifications@FreeBSD.org -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 ============================================================================= FreeBSD-SA-26:10.tty Security Advisory The FreeBSD Project Topic: Kernel use-after-free bug in the TIOCNOTTY handler Category: core Module: tty Announced: 2026-04-21 Credits: Nicholas Carlini using Claude, Anthropic Affects: All supported versions of FreeBSD. Corrected: 2026-04-21 15:43:02 UTC (stable/15, 15.0-STABLE) 2026-04-21 15:44:27 UTC (releng/15.0, 15.0-RELEASE-p6) 2026-04-21 15:43:13 UTC (stable/14, 14.4-STABLE) 2026-04-21 15:45:31 UTC (releng/14.4, 14.4-RELEASE-p2) 2026-04-21 15:46:01 UTC (releng/14.3, 14.3-RELEASE-p11) 2026-04-21 15:43:56 UTC (stable/13, 13.5-STABLE) 2026-04-21 15:47:07 UTC (releng/13.5, 13.5-RELEASE-p12) CVE Name: CVE-2026-5398 For general information regarding FreeBSD Security Advisories, including descriptions of the fields above, security branches, and the following sections, please visit . I. Background TIOCNOTTY is an ioctl(2) operation which allows a process to detach itself from its controlling terminal. Unprivileged processes may use this ioctl. See the tty(4) manual page for more information on its usage. II. Problem Description The implementation of TIOCNOTTY failed to clear a back-pointer from the structure representing the controlling terminal to the calling process' session. If the invoking process then exits, the terminal structure may end up containing a pointer to freed memory. III. Impact A malicious process can abuse the dangling pointer to grant itself root 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, or the i386 platform on FreeBSD 13, 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 15.0] # fetch https://security.FreeBSD.org/patches/SA-26:10/tty-15.patch # fetch https://security.FreeBSD.org/patches/SA-26:10/tty-15.patch.asc # gpg --verify tty-15.patch.asc [FreeBSD 14.4] # fetch https://security.FreeBSD.org/patches/SA-26:10/tty-14.4.patch # fetch https://security.FreeBSD.org/patches/SA-26:10/tty-14.4.patch.asc # gpg --verify tty-14.4.patch.asc [FreeBSD 14.3] # fetch https://security.FreeBSD.org/patches/SA-26:10/tty-14.3.patch # fetch https://security.FreeBSD.org/patches/SA-26:10/tty-14.3.patch.asc # gpg --verify tty-14.3.patch.asc [FreeBSD 13.5] # fetch https://security.FreeBSD.org/patches/SA-26:10/tty-13.patch # fetch https://security.FreeBSD.org/patches/SA-26:10/tty-13.patch.asc # gpg --verify tty-13.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/ 0c6b1e0864b8 stable/15-n283065 releng/15.0/ fdee312d0c97 releng/15.0-n281022 stable/14/ f46210a7ab32 stable/14-n273997 releng/14.4/ af294329c57f releng/14.4-n273685 releng/14.3/ 44077c07f19f releng/14.3-n271485 stable/13/ 5eae7f23fe0e stable/13-n259845 releng/13.5/ 2862a33bdd1c releng/13.5-n259210 - ------------------------------------------------------------------------- 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----- iQIzBAEBCgAdFiEEthUnfoEIffdcgYM7bljekB8AGu8FAmnnoaMACgkQbljekB8A Gu8qzA//fuGHRB8Y+n+EUyAGycr0PGMeG423hykkYBAvfBJJP5RYv4Ter79YAeuu zqXqijjr+yyKcE1+km63/koxUXZmkbpR2Xt/0i2d3jAqnrUioZqwc+llCgqhh6Dr AhyDn+xCtCWJow0Iktlk6ZHEuQLX6kwGxT/1cvmcnhZE8XQf2PNEbRk8oit+kf8c LQZF2EBK4wPh5Lik8DvqoyX1k7B44jVhL2AMqs/2fRdTFluY/MIgvbRsRdCQRLJE doXA2YdDljkTJpAPIg31WP6C7L0LPkeyRm4Xn3zBt4SalyiChfQ9kQYcdQS7/lt4 LUyrQKQHVtVx2SseYFTtPoncYl2IEmaHOAZkQrfzxFybYryoq4macGbuNZh0Aygq mpIAIIDKAyKQCcDGzluRL4ksoPyw9Kav7SJJ83P9khrKINaNg5NZc1Ptc7K/UvSk H5XKwHBaURcXGzl1crBtqbbK5lEvO/UaxXraMwqCTM+WqF7dND2KvSbZEma/FJ8l 7Wcszs2dvgC2dQghlmRlxxYvMGzf49XO4+Y64WarMqmLTAyDV9nBrZGMUj1M2nqC rgylEscbOn8z/Yq8vpr0sydYRVDBHtVMOaztsqFylGnzRfSjQQH3yuJ40ngvy9yo GexBhYXFyrruuuuz9p9xplIRzVkHVjkrm9/zwe4bSBylQ+/MeGQ= =crMa -----END PGP SIGNATURE-----