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CVE-2026-74691— net: thunderbolt: Tear down DMA paths before stopping the rings

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会开源的一个操作系统内核。 Linux kernel存在安全漏洞，该漏洞源于thunderbolt网络驱动的teardown顺序错误，即在停止ring和释放帧缓冲区后才禁用DMA路径，导致在途数据无法排空，可能造成XDomain控制通道关闭，最终导致拒绝服务。

CVSS 8.8 · High EPSS 0.26% · P16

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service

Affected Version Matrix 16

VendorProduct Version RangeStatus
Linux Linux e69b6c02b4c3b8d03be7136f90dd9551ad5a5a5e< 7cce39109206bc5497e0953806563644b88bfc44 affected
e69b6c02b4c3b8d03be7136f90dd9551ad5a5a5e< 0da9a6d27155ad072dd76db8cd637feead99a0e0 affected
e69b6c02b4c3b8d03be7136f90dd9551ad5a5a5e< b5a21615f627c48dafaa6ef82a34a5b97a4352aa affected
e69b6c02b4c3b8d03be7136f90dd9551ad5a5a5e< 103a9b663ac1cacb8465aeff18f84a247154a562 affected
e69b6c02b4c3b8d03be7136f90dd9551ad5a5a5e< 4dd71cb0d23d40cb58fe4261c7bd183dca66caa0 affected
e69b6c02b4c3b8d03be7136f90dd9551ad5a5a5e< 9a482b2b117e5fa656b6d24fc01799e8ac2d4368 affected
e69b6c02b4c3b8d03be7136f90dd9551ad5a5a5e< 68bf02b6b4ad3f748c6db71fd77b6c0402d252f4 affected
4.15 affected
… +8 more rows
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I. Basic Information for CVE-2026-74691

Vulnerability Information
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Vulnerability Title
net: thunderbolt: Tear down DMA paths before stopping the rings
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会开源的一个操作系统内核。 Linux kernel存在安全漏洞，该漏洞源于thunderbolt网络驱动的teardown顺序错误，即在停止ring和释放帧缓冲区后才禁用DMA路径，导致在途数据无法排空，可能造成XDomain控制通道关闭，最终导致拒绝服务。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux e69b6c02b4c3b8d03be7136f90dd9551ad5a5a5e ~ 7cce39109206bc5497e0953806563644b88bfc44 -
Linux Linux 4.15 -

II. Public POCs for CVE-2026-74691

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III. Intelligence Information for CVE-2026-74691

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Patches & Fixes for CVE-2026-74691 (6)

Other References for CVE-2026-74691 (1)

Same Patch Batch · Linux · 2026-08-22 · 149 CVEs total

CVE-2026-74705 10.0 CRITICAL udp: fix potential use-after-free in tunnel segmentation
CVE-2026-74612 10.0 CRITICAL veth: fix skb length accounting after XDP frag adjustment
CVE-2026-74669 9.8 CRITICAL ipvs: clear IPv4 options after rebasing tunnel ICMP errors
CVE-2026-74628 9.8 CRITICAL net/x25: fix use-after-free of the socket by its timers
CVE-2026-74723 9.8 CRITICAL btrfs: lzo: reject inline extents without valid headers
CVE-2026-74617 9.8 CRITICAL dibs: initialise dibs->lock in dibs_dev_alloc()
CVE-2026-74616 9.8 CRITICAL xdp: reject clones that overrun skb_shared_info tailroom
CVE-2026-74611 9.8 CRITICAL tls: rx: restore msg_iter before TLS 1.3 optimistic retry
CVE-2026-74608 9.8 CRITICAL smb: client: Fix use-after-free in cifs_try_adding_channels()
CVE-2026-74688 9.8 CRITICAL sctp: clear control chunk transport if it is being removed
CVE-2026-74727 9.8 CRITICAL ovpn: skip rehash for peers already removed from by_id
CVE-2026-74662 9.8 CRITICAL inet: frags: publish queues before arming timer
CVE-2026-74597 9.8 CRITICAL ip6_tunnel: clear skb2->cb[] in ip6ip6_err()
CVE-2026-74586 9.8 CRITICAL sctp: clear new_transport when removing a peer
CVE-2026-74730 9.8 CRITICAL NFS: Pin the 'struct nfs_server' during a FREE_STATEID call
CVE-2026-74591 9.8 CRITICAL mm/filemap: __filemap_add_folio() restore index before retrying
CVE-2026-74588 9.8 CRITICAL sctp: keep chunk->transport in step with the list it is queued on
CVE-2026-74587 9.8 CRITICAL sctp: fix use-after-free of cached ASCONF chunk
CVE-2026-74712 9.3 CRITICAL vdpa/mlx5: Fix buffer length in create_direct_keys()
CVE-2026-74665 9.1 CRITICAL net: fix skb length accounting after generic XDP frag adjustment

Showing top 20 of 149 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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