FKIE_CVE-2026-74691
Vulnerability from fkie_nvd - Published: 2026-08-22 16:16 - Updated: 2026-08-25 06:18
Severity
Summary
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.
References
Impacted products
| Vendor | Product | Version |
|---|
{
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"drivers/net/thunderbolt/main.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "7cce39109206bc5497e0953806563644b88bfc44",
"status": "affected",
"version": "e69b6c02b4c3b8d03be7136f90dd9551ad5a5a5e",
"versionType": "git"
},
{
"lessThan": "0da9a6d27155ad072dd76db8cd637feead99a0e0",
"status": "affected",
"version": "e69b6c02b4c3b8d03be7136f90dd9551ad5a5a5e",
"versionType": "git"
},
{
"lessThan": "b5a21615f627c48dafaa6ef82a34a5b97a4352aa",
"status": "affected",
"version": "e69b6c02b4c3b8d03be7136f90dd9551ad5a5a5e",
"versionType": "git"
},
{
"lessThan": "103a9b663ac1cacb8465aeff18f84a247154a562",
"status": "affected",
"version": "e69b6c02b4c3b8d03be7136f90dd9551ad5a5a5e",
"versionType": "git"
},
{
"lessThan": "4dd71cb0d23d40cb58fe4261c7bd183dca66caa0",
"status": "affected",
"version": "e69b6c02b4c3b8d03be7136f90dd9551ad5a5a5e",
"versionType": "git"
},
{
"lessThan": "9a482b2b117e5fa656b6d24fc01799e8ac2d4368",
"status": "affected",
"version": "e69b6c02b4c3b8d03be7136f90dd9551ad5a5a5e",
"versionType": "git"
},
{
"lessThan": "68bf02b6b4ad3f748c6db71fd77b6c0402d252f4",
"status": "affected",
"version": "e69b6c02b4c3b8d03be7136f90dd9551ad5a5a5e",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"drivers/net/thunderbolt/main.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "4.15"
},
{
"lessThan": "4.15",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.216",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.183",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.152",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.104",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.45",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.9",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: thunderbolt: Tear down DMA paths before stopping the rings\n\ntbnet_tear_down() stops both rings and frees their frame buffers before\ncalling tb_xdomain_disable_paths(). tb_ring_stop() zeroes the ring\u0027s\ndescriptor base and tbnet_free_buffers() unmaps and frees the pages the\nframes sit in, so by the time __tb_path_deactivate_hop() polls the hop\u0027s\n\u0027pending\u0027 bit, anything still in flight has nowhere to drain to.\n\nThe teardown sequence has been in this order since the driver was added.\nThe setup path has not: commit ff7cd07f3064 (\"net: thunderbolt: Enable\nDMA paths only after rings are enabled\") moved the path enable to the end\nof tbnet_connected_work() and documented why:\n\n\t/* Both logins successful so enable the rings, high-speed DMA\n\t * paths and start the network device queue.\n\t *\n\t * Note we enable the DMA paths last to make sure we have primed\n\t * the Rx ring before any incoming packets are allowed to\n\t * arrive.\n\t */\n\nTeardown was never updated to match, so the rings and the paths now come\ndown in the same order they go up instead of in reverse.\n\nOn an ASMedia ASM4242 host router the \u0027pending\u0027 bit then never clears:\nevery teardown burns the full 500 ms timeout and\n__tb_path_deactivate_hop() returns -ETIMEDOUT. Raising the timeout to\n5 s does not help, so the hop is not slow to drain, it never drains\nat all.\n\nThe failure is invisible above the thunderbolt core.\n__tb_path_deactivate_hops() is void and only calls tb_port_warn();\ntb_path_deactivate(), tb_tunnel_deactivate() and\n__tb_disconnect_xdomain_paths() are void as well, and\ntb_disconnect_xdomain_paths() ends in an unconditional \"return 0\". So\ntb_xdomain_disable_paths() reports success and the netdev_warn() below\nit never fires. Repeated teardowns eventually take the XDomain control\nchannel down, after which the peer node is gone and only a power cycle\nbrings the controller back.\n\nDeactivating the paths first fixes it. Measured with kretprobes on a\nstock v6.17 tree with no other patches applied, on a link that was up\nand had just carried traffic:\n\n before: __tb_path_deactivate_hop() returns 0 for the first hop, then\n -ETIMEDOUT for the second 500335 us later\n after: 0 for both, 525 us apart\n\nAlternating the two orderings ABBA over three load levels, four\nteardowns per arm: every teardown failed before the change (21 of 21\nthat ran), none failed after (0 of 24). The before arms ran short\nbecause the link died partway through. The same split shows up when\nthe interface is enslaved to a bond instead of just brought down, which\nis how I ran into this in the first place. Throughput and latency after\nthe change are unchanged.\n\nHosts whose routers drain the hop despite the stale descriptor base see\nno functional difference, since the paths end up deactivated either way."
}
],
"id": "CVE-2026-74691",
"lastModified": "2026-08-25T06:18:52.440",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "ADJACENT_NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 8.8,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"exploitabilityScore": 2.8,
"impactScore": 5.9,
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary"
}
]
},
"published": "2026-08-22T16:16:43.527",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/0da9a6d27155ad072dd76db8cd637feead99a0e0"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/103a9b663ac1cacb8465aeff18f84a247154a562"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/4dd71cb0d23d40cb58fe4261c7bd183dca66caa0"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/68bf02b6b4ad3f748c6db71fd77b6c0402d252f4"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/7cce39109206bc5497e0953806563644b88bfc44"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/9a482b2b117e5fa656b6d24fc01799e8ac2d4368"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/b5a21615f627c48dafaa6ef82a34a5b97a4352aa"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Received"
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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