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CVE-2026-72340 (GCVE-0-2026-72340)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:55 – Updated: 2026-08-17 05:42
VLAI
Title
net: microchip: vcap: fix races on the shared Super VCAP block
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.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 71c9de995260222e739020104d477af4775a6d26 , < 786456d0a244bbd405dfc60e4de51f8b348b9cb1 (git)
Affected: 71c9de995260222e739020104d477af4775a6d26 , < 49806bef9572a2e012610517bc14ed0a4db0d1fc (git)
Affected: 71c9de995260222e739020104d477af4775a6d26 , < 1e71a40d101547380590db582213c1f1dce1f041 (git)
Affected: 71c9de995260222e739020104d477af4775a6d26 , < 952928564cc5fdb06f92d7e25c6cd2e1d816362b (git)
Affected: 71c9de995260222e739020104d477af4775a6d26 , < d7a8d500d7e42837bd8dce40cb52c97c6e8706a9 (git)
guessed Create a notification for this product.
Linux Linux Affected: 6.2
Unaffected: 0 , < 6.2 (semver)
Unaffected: 6.6.145 , ≤ 6.6.* (semver)
Unaffected: 6.12.97 , ≤ 6.12.* (semver)
Unaffected: 6.18.40 , ≤ 6.18.* (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "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",
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            "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": [
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              "version": "6.2"
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              "version": "6.12.97",
              "versionType": "semver"
            },
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              "versionType": "semver"
            },
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              "status": "unaffected",
              "version": "7.1.5",
              "versionType": "semver"
            },
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              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
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        }
      ],
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                  "versionStartIncluding": "6.2",
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                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.97",
                  "versionStartIncluding": "6.2",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "versionStartIncluding": "6.2",
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                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.5",
                  "versionStartIncluding": "6.2",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "6.2",
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              "negate": false,
              "operator": "OR"
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      "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."
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      ],
      "metrics": [
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            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
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          },
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            {
              "lang": "en",
              "value": "AV:L - Exploitation requires local kernel interfaces: tc-flower netlink/offload (ndo_setup_tc) to program VCAP rules and debugfs reads that issue hardware READs; remote packets do not reach this code path.\nAC:L - An attacker can reliably win the race by running concurrent threads\u2014one repeatedly reading VCAP debugfs dumps while another issues tc-flower add/modify/delete operations on a different Super VCAP instance (IS0 vs IS2).\nPR:L - The tc-flower write path requires CAP_NET_ADMIN, reachable by an unprivileged local user via user namespaces (unshare -Ur); debugfs VCAP dumps are readable with CAP_SYS_ADMIN, likewise obtainable in a user namespace.\nUI:N - No victim interaction is required; the attacker self-triggers the race with automated concurrent debugfs reads and tc-flower netlink operations.\nS:U - Impact stays within the kernel/switch management security boundary\u2014corrupting on-chip TCAM ACL entries and forwarding policy\u2014not a VM escape, IOMMU bypass, or cross-authority sandbox breakout.\nC:H - Corrupted Super VCAP TCAM entries can alter match/action fields to redirect or CPU-copy traffic to attacker-chosen ports, enabling interception of confidential traffic traversing the switch.\nI:H - The race causes arbitrary wrong key/mask/action data to be committed to hardware ACL entries, enabling unauthorized modification of line-rate switching policy including redirects, drops, and policing bypass.\nA:H - Corrupted TCAM rules can black-hole, misroute, or otherwise disable forwarding for arbitrary ports/VLANs on production SparX5/LAN969x switches, causing repeated high-impact network availability loss."
            }
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      "providerMetadata": {
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    "cveId": "CVE-2026-72340",
    "datePublished": "2026-08-15T05:55:47.119Z",
    "dateReserved": "2026-08-09T03:40:39.920Z",
    "dateUpdated": "2026-08-17T05:42:59.028Z",
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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.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"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\",\"versions\":[{\"version\":\"71c9de995260222e739020104d477af4775a6d26\",\"lessThan\":\"786456d0a244bbd405dfc60e4de51f8b348b9cb1\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"71c9de995260222e739020104d477af4775a6d26\",\"lessThan\":\"49806bef9572a2e012610517bc14ed0a4db0d1fc\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"71c9de995260222e739020104d477af4775a6d26\",\"lessThan\":\"1e71a40d101547380590db582213c1f1dce1f041\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"71c9de995260222e739020104d477af4775a6d26\",\"lessThan\":\"952928564cc5fdb06f92d7e25c6cd2e1d816362b\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"71c9de995260222e739020104d477af4775a6d26\",\"lessThan\":\"d7a8d500d7e42837bd8dce40cb52c97c6e8706a9\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"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\",\"versions\":[{\"version\":\"6.2\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"6.2\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.145\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.97\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.40\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1.5\",\"lessThanOrEqual\":\"7.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":7.8,\"baseSeverity\":\"HIGH\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":5.9}]},\"references\":[{\"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\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-19T17:08:04+00:00",
      "cve": "CVE-2026-72340",
      "id": "CVE-2026-72340",
      "initial_release_date": "2026-08-15T00:00:00+00:00",
      "product_status:known_not_affected": "274",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: net: microchip: vcap: fix races on the shared Super VCAP block",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72340.json",
      "version": "3"
    }
  }
}



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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.


Detection rules are retrieved from Rulezet.