FKIE_CVE-2026-72340
Vulnerability from fkie_nvd - Published: 2026-08-15 06:22 - Updated: 2026-08-17 06:18
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved:
net: microchip: vcap: fix races on the shared Super VCAP block
The VCAP instances on a chip are not independent, yet they are locked
independently. On sparx5 and lan969x the IS0 and IS2 instances are
backed by the same Super VCAP hardware block and share its cache and
command registers: every access drives the shared VCAP_SUPER_CTRL
register and moves data through the shared cache registers.
Accessing one instance therefore races with accessing another. The
per-instance admin->lock cannot prevent this, as each instance takes a
different lock.
The locking issue is mostly disguised by the fact that the core usage of
the vcap api runs under rtnl. However, the full rule dump in debugfs
decodes rules straight from hardware (a READ command followed by a cache
read) and runs outside rtnl, so it races a concurrent tc-flower rule
write to another Super VCAP instance.
Besides corrupting the dump, the read repopulates the shared cache
between the writers cache fill and its write command, so the writer
commits the wrong data and corrupts the hardware entry.
Introduce vcap_lock() and vcap_unlock() helpers and route every rule
lock site in the VCAP API and its debugfs code through them. Replace the
per-instance admin->lock with a single mutex in struct vcap_control that
serializes access to all instances. The helpers reach it through a new
admin->vctrl back-pointer, and the clients initialise and destroy the
control lock instead of a per-instance one.
No path holds more than one instance lock, so collapsing them onto a
single mutex cannot self-deadlock.
References
Impacted products
| Vendor | Product | Version |
|---|
{
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"drivers/net/ethernet/microchip/lan966x/lan966x_vcap_impl.c",
"drivers/net/ethernet/microchip/sparx5/sparx5_vcap_impl.c",
"drivers/net/ethernet/microchip/vcap/vcap_api.c",
"drivers/net/ethernet/microchip/vcap/vcap_api.h",
"drivers/net/ethernet/microchip/vcap/vcap_api_debugfs.c",
"drivers/net/ethernet/microchip/vcap/vcap_api_debugfs_kunit.c",
"drivers/net/ethernet/microchip/vcap/vcap_api_kunit.c",
"drivers/net/ethernet/microchip/vcap/vcap_api_private.h"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "786456d0a244bbd405dfc60e4de51f8b348b9cb1",
"status": "affected",
"version": "71c9de995260222e739020104d477af4775a6d26",
"versionType": "git"
},
{
"lessThan": "49806bef9572a2e012610517bc14ed0a4db0d1fc",
"status": "affected",
"version": "71c9de995260222e739020104d477af4775a6d26",
"versionType": "git"
},
{
"lessThan": "1e71a40d101547380590db582213c1f1dce1f041",
"status": "affected",
"version": "71c9de995260222e739020104d477af4775a6d26",
"versionType": "git"
},
{
"lessThan": "952928564cc5fdb06f92d7e25c6cd2e1d816362b",
"status": "affected",
"version": "71c9de995260222e739020104d477af4775a6d26",
"versionType": "git"
},
{
"lessThan": "d7a8d500d7e42837bd8dce40cb52c97c6e8706a9",
"status": "affected",
"version": "71c9de995260222e739020104d477af4775a6d26",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"drivers/net/ethernet/microchip/lan966x/lan966x_vcap_impl.c",
"drivers/net/ethernet/microchip/sparx5/sparx5_vcap_impl.c",
"drivers/net/ethernet/microchip/vcap/vcap_api.c",
"drivers/net/ethernet/microchip/vcap/vcap_api.h",
"drivers/net/ethernet/microchip/vcap/vcap_api_debugfs.c",
"drivers/net/ethernet/microchip/vcap/vcap_api_debugfs_kunit.c",
"drivers/net/ethernet/microchip/vcap/vcap_api_kunit.c",
"drivers/net/ethernet/microchip/vcap/vcap_api_private.h"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "6.2"
},
{
"lessThan": "6.2",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.145",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.97",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.40",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.5",
"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: microchip: vcap: fix races on the shared Super VCAP block\n\nThe VCAP instances on a chip are not independent, yet they are locked\nindependently. On sparx5 and lan969x the IS0 and IS2 instances are\nbacked by the same Super VCAP hardware block and share its cache and\ncommand registers: every access drives the shared VCAP_SUPER_CTRL\nregister and moves data through the shared cache registers.\n\nAccessing one instance therefore races with accessing another. The\nper-instance admin-\u003elock cannot prevent this, as each instance takes a\ndifferent lock.\n\nThe locking issue is mostly disguised by the fact that the core usage of\nthe vcap api runs under rtnl. However, the full rule dump in debugfs\ndecodes rules straight from hardware (a READ command followed by a cache\nread) and runs outside rtnl, so it races a concurrent tc-flower rule\nwrite to another Super VCAP instance.\n\nBesides corrupting the dump, the read repopulates the shared cache\nbetween the writers cache fill and its write command, so the writer\ncommits the wrong data and corrupts the hardware entry.\n\nIntroduce vcap_lock() and vcap_unlock() helpers and route every rule\nlock site in the VCAP API and its debugfs code through them. Replace the\nper-instance admin-\u003elock with a single mutex in struct vcap_control that\nserializes access to all instances. The helpers reach it through a new\nadmin-\u003evctrl back-pointer, and the clients initialise and destroy the\ncontrol lock instead of a per-instance one.\n\nNo path holds more than one instance lock, so collapsing them onto a\nsingle mutex cannot self-deadlock."
}
],
"id": "CVE-2026-72340",
"lastModified": "2026-08-17T06:18:37.763",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 7.8,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"exploitabilityScore": 1.8,
"impactScore": 5.9,
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary"
}
]
},
"published": "2026-08-15T06:22:07.280",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/1e71a40d101547380590db582213c1f1dce1f041"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/49806bef9572a2e012610517bc14ed0a4db0d1fc"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/786456d0a244bbd405dfc60e4de51f8b348b9cb1"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/952928564cc5fdb06f92d7e25c6cd2e1d816362b"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/d7a8d500d7e42837bd8dce40cb52c97c6e8706a9"
}
],
"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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