# CVE-2026-74691: net: thunderbolt: Tear down DMA paths before stopping the rings CVE-2026-74691 is fixed in 47 products on 1 platform, first by DEBIAN-CVE-2026-74691, released August 27, 2026. It is not reported as exploited. Patch Radar priority: High. - Web page: https://patchblox.com/security/cve/CVE-2026-74691 - Priority: High - CVSS: 8.8 (Moderate) - EPSS: 0.0026 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Aug 22, 2026 - Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-74691 ## Description In the Linux kernel, the following vulnerability has been resolved: net: thunderbolt: Tear down DMA paths before stopping the rings tbnet_tear_down() stops both rings and frees their frame buffers before calling tb_xdomain_disable_paths(). tb_ring_stop() zeroes the ring's descriptor base and tbnet_free_buffers() unmaps and frees the pages the frames sit in, so by the time __tb_path_deactivate_hop() polls the hop's 'pending' bit, anything still in flight has nowhere to drain to. The teardown sequence has been in this order since the driver was added. The setup path has not: commit ff7cd07f3064 ("net: thunderbolt: Enable DMA paths only after rings are enabled") moved the path enable to the end of tbnet_connected_work() and documented why: /* Both logins successful so enable the rings, high-speed DMA * paths and start the network device queue. * * Note we enable the DMA paths last to make sure we have primed * the Rx ring before any incoming packets are allowed to * arrive. */ Teardown was never updated to match, so the rings and the paths now come down in the same order they go up instead of in reverse. On an ASMedia ASM4242 host router the 'pending' bit then never clears: every teardown burns the full 500 ms timeout and __tb_path_deactivate_hop() returns -ETIMEDOUT. Raising the timeout to 5 s does not help, so the hop is not slow to drain, it never drains at all. The failure is invisible above the thunderbolt core. __tb_path_deactivate_hops() is void and only calls tb_port_warn(); tb_path_deactivate(), tb_tunnel_deactivate() and __tb_disconnect_xdomain_paths() are void as well, and tb_disconnect_xdomain_paths() ends in an unconditional "return 0". So tb_xdomain_disable_paths() reports success and the netdev_warn() below it never fires. Repeated teardowns eventually take the XDomain control channel down, after which the peer node is gone and only a power cycle brings the controller back. Deactivating the paths first fixes it. Measured with kretprobes on a stock v6.17 tree with no other patches applied, on a link that was up and had just carried traffic: before: __tb_path_deactivate_hop() returns 0 for the first hop, then -ETIMEDOUT for the second 500335 us later after: 0 for both, 525 us apart Alternating the two orderings ABBA over three load levels, four teardowns per arm: every teardown failed before the change (21 of 21 that ran), none failed after (0 of 24). The before arms ran short because the link died partway through. The same split shows up when the interface is enslaved to a bond instead of just brought down, which is how I ran into this in the first place. Throughput and latency after the change are unchanged. Hosts whose routers drain the hop despite the stale descriptor base see no functional difference, since the paths end up deactivated either way. ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | kernel-64kb sles 15.7 | 6.4.0-150700.53.90.1 | [SUSE-SU-2026:5091-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-5091-1.md) | Nov 7, 2026 | | Linux | kernel-azure sles 15.7 | 6.4.0-150700.53.90.1 | [SUSE-SU-2026:5091-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-5091-1.md) | Nov 7, 2026 | | Linux | kernel-default sles 15.7 | 6.4.0-150700.53.90.1 | [SUSE-SU-2026:5091-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-5091-1.md) | Nov 7, 2026 | | Linux | kernel-default-base sles 15.7 | 6.4.0-150700.53.90.1.150700.17.51.1 | [SUSE-SU-2026:5091-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-5091-1.md) | Nov 7, 2026 | | Linux | kernel-docs sles 15.7 | 6.4.0-150700.53.90.1 | [SUSE-SU-2026:5091-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-5091-1.md) | Nov 7, 2026 | | Linux | kernel-livepatch-SLE15-SP7_Update_24 sles 15.7 | 1-150700.15.3.1 | [SUSE-SU-2026:5091-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-5091-1.md) | Nov 7, 2026 | | Linux | kernel-obs-build sles 15.7 | 6.4.0-150700.53.90.1 | [SUSE-SU-2026:5091-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-5091-1.md) | Nov 7, 2026 | | Linux | kernel-source sles 15.7 | 6.4.0-150700.53.90.1 | [SUSE-SU-2026:5091-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-5091-1.md) | Nov 7, 2026 | | Linux | kernel-syms sles 15.7 | 6.4.0-150700.53.90.1 | [SUSE-SU-2026:5091-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-5091-1.md) | Nov 7, 2026 | | Linux | kernel-uek ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-core ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-core ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-debug ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-debug ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-debug-core ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-debug-core ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-debug-devel ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-debug-devel ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-debug-modules ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-debug-modules ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-debug-modules-core ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-debug-modules-core ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-debug-modules-deprecated ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-debug-modules-deprecated ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-debug-modules-desktop ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-debug-modules-desktop ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-debug-modules-extra ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-debug-modules-extra ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-debug-modules-extra-netfilter ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-debug-modules-extra-netfilter ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-debug-modules-usb ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-debug-modules-usb ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-debug-modules-wireless ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-debug-modules-wireless ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-devel ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-devel ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-doc ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-doc ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-modules ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-modules ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-modules-core ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-modules-core ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-modules-deprecated ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-modules-deprecated ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-modules-desktop ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-modules-desktop ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-modules-extra ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-modules-extra ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-modules-extra-netfilter ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-modules-extra-netfilter ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-modules-usb ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-modules-usb ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-modules-wireless ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-modules-wireless ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-tools ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek-tools ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek64k ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek64k ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek64k-core ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek64k-core ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek64k-devel ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek64k-devel ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek64k-modules ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek64k-modules ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek64k-modules-core ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek64k-modules-core ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek64k-modules-deprecated ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek64k-modules-deprecated ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek64k-modules-desktop ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek64k-modules-desktop ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek64k-modules-extra ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek64k-modules-extra ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek64k-modules-extra-netfilter ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek64k-modules-extra-netfilter ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek64k-modules-usb ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek64k-modules-usb ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek64k-modules-wireless ol 10 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-uek64k-modules-wireless ol 9 | 0:6.12.0-206.104.3.3.el9uek | [ELSA-2026-500248](https://patchblox.com/security/data/fix/linux/elsa-2026-500248.md) | Sep 4, 2026 | | Linux | kernel-zfcpdump sles 15.7 | 6.4.0-150700.53.90.1 | [SUSE-SU-2026:5091-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-5091-1.md) | Nov 7, 2026 | | Linux | linux Debian 12.15 (bookworm) | 6.1.187-1 | [DEBIAN-CVE-2026-74691](https://patchblox.com/security/data/fix/linux/debian-cve-2026-74691.md) | Aug 27, 2026 | | Linux | linux Debian 13.5 (trixie) | 6.12.105-1 | [DEBIAN-CVE-2026-74691](https://patchblox.com/security/data/fix/linux/debian-cve-2026-74691.md) | Aug 27, 2026 | | Linux | linux Debian 14 | 7.1.9-1 | [DEBIAN-CVE-2026-74691](https://patchblox.com/security/data/fix/linux/debian-cve-2026-74691.md) | Aug 27, 2026 | | Linux | linux-6.12 Debian 12.15 (bookworm) | 6.12.107-1~deb12u1 | [DEBIAN-CVE-2026-74691](https://patchblox.com/security/data/fix/linux/debian-cve-2026-74691.md) | Aug 27, 2026 | --- Data as of 2026-11-09T01:18:40Z UTC. 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