CVE-2026-43392 (GCVE-0-2026-43392)

Vulnerability from cvelistv5 – Published: 2026-05-08 14:21 – Updated: 2026-05-08 14:21
VLAI?
Title
sched_ext: Fix starvation of scx_enable() under fair-class saturation
Summary
In the Linux kernel, the following vulnerability has been resolved: sched_ext: Fix starvation of scx_enable() under fair-class saturation During scx_enable(), the READY -> ENABLED task switching loop changes the calling thread's sched_class from fair to ext. Since fair has higher priority than ext, saturating fair-class workloads can indefinitely starve the enable thread, hanging the system. This was introduced when the enable path switched from preempt_disable() to scx_bypass() which doesn't protect against fair-class starvation. Note that the original preempt_disable() protection wasn't complete either - in partial switch modes, the calling thread could still be starved after preempt_enable() as it may have been switched to ext class. Fix it by offloading the enable body to a dedicated system-wide RT (SCHED_FIFO) kthread which cannot be starved by either fair or ext class tasks. scx_enable() lazily creates the kthread on first use and passes the ops pointer through a struct scx_enable_cmd containing the kthread_work, then synchronously waits for completion. The workfn runs on a different kthread from sch->helper (which runs disable_work), so it can safely flush disable_work on the error path without deadlock.
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 8c2090c504e998c8f34ec870bae71dafcc96a6e0 , < e0b14bf06393be137d3efb6a3b7cd5b4b9810a6b (git)
Affected: 8c2090c504e998c8f34ec870bae71dafcc96a6e0 , < c44198f25fdfecc0ec0fe366bf8a47fe17d8e229 (git)
Affected: 8c2090c504e998c8f34ec870bae71dafcc96a6e0 , < 05ab9ec5dc24f234e0a2fecf3e6ff937c68f7d81 (git)
Affected: 8c2090c504e998c8f34ec870bae71dafcc96a6e0 , < b06ccbabe2506fd70b9167a644978b049150224a (git)
Create a notification for this product.
    Linux Linux Affected: 6.12
Unaffected: 0 , < 6.12 (semver)
Unaffected: 6.12.78 , ≤ 6.12.* (semver)
Unaffected: 6.18.20 , ≤ 6.18.* (semver)
Unaffected: 6.19.9 , ≤ 6.19.* (semver)
Unaffected: 7.0 , ≤ * (original_commit_for_fix)
Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/sched/ext.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "e0b14bf06393be137d3efb6a3b7cd5b4b9810a6b",
              "status": "affected",
              "version": "8c2090c504e998c8f34ec870bae71dafcc96a6e0",
              "versionType": "git"
            },
            {
              "lessThan": "c44198f25fdfecc0ec0fe366bf8a47fe17d8e229",
              "status": "affected",
              "version": "8c2090c504e998c8f34ec870bae71dafcc96a6e0",
              "versionType": "git"
            },
            {
              "lessThan": "05ab9ec5dc24f234e0a2fecf3e6ff937c68f7d81",
              "status": "affected",
              "version": "8c2090c504e998c8f34ec870bae71dafcc96a6e0",
              "versionType": "git"
            },
            {
              "lessThan": "b06ccbabe2506fd70b9167a644978b049150224a",
              "status": "affected",
              "version": "8c2090c504e998c8f34ec870bae71dafcc96a6e0",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "kernel/sched/ext.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.12"
            },
            {
              "lessThan": "6.12",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.78",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.20",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.78",
                  "versionStartIncluding": "6.12",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.20",
                  "versionStartIncluding": "6.12",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19.9",
                  "versionStartIncluding": "6.12",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0",
                  "versionStartIncluding": "6.12",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsched_ext: Fix starvation of scx_enable() under fair-class saturation\n\nDuring scx_enable(), the READY -\u003e ENABLED task switching loop changes the\ncalling thread\u0027s sched_class from fair to ext. Since fair has higher\npriority than ext, saturating fair-class workloads can indefinitely starve\nthe enable thread, hanging the system. This was introduced when the enable\npath switched from preempt_disable() to scx_bypass() which doesn\u0027t protect\nagainst fair-class starvation. Note that the original preempt_disable()\nprotection wasn\u0027t complete either - in partial switch modes, the calling\nthread could still be starved after preempt_enable() as it may have been\nswitched to ext class.\n\nFix it by offloading the enable body to a dedicated system-wide RT\n(SCHED_FIFO) kthread which cannot be starved by either fair or ext class\ntasks. scx_enable() lazily creates the kthread on first use and passes the\nops pointer through a struct scx_enable_cmd containing the kthread_work,\nthen synchronously waits for completion.\n\nThe workfn runs on a different kthread from sch-\u003ehelper (which runs\ndisable_work), so it can safely flush disable_work on the error path\nwithout deadlock."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-08T14:21:36.692Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/e0b14bf06393be137d3efb6a3b7cd5b4b9810a6b"
        },
        {
          "url": "https://git.kernel.org/stable/c/c44198f25fdfecc0ec0fe366bf8a47fe17d8e229"
        },
        {
          "url": "https://git.kernel.org/stable/c/05ab9ec5dc24f234e0a2fecf3e6ff937c68f7d81"
        },
        {
          "url": "https://git.kernel.org/stable/c/b06ccbabe2506fd70b9167a644978b049150224a"
        }
      ],
      "title": "sched_ext: Fix starvation of scx_enable() under fair-class saturation",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-43392",
    "datePublished": "2026-05-08T14:21:36.692Z",
    "dateReserved": "2026-05-01T14:12:56.007Z",
    "dateUpdated": "2026-05-08T14:21:36.692Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-43392\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-05-08T15:16:50.583\",\"lastModified\":\"2026-05-08T15:16:50.583\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nsched_ext: Fix starvation of scx_enable() under fair-class saturation\\n\\nDuring scx_enable(), the READY -\u003e ENABLED task switching loop changes the\\ncalling thread\u0027s sched_class from fair to ext. Since fair has higher\\npriority than ext, saturating fair-class workloads can indefinitely starve\\nthe enable thread, hanging the system. This was introduced when the enable\\npath switched from preempt_disable() to scx_bypass() which doesn\u0027t protect\\nagainst fair-class starvation. Note that the original preempt_disable()\\nprotection wasn\u0027t complete either - in partial switch modes, the calling\\nthread could still be starved after preempt_enable() as it may have been\\nswitched to ext class.\\n\\nFix it by offloading the enable body to a dedicated system-wide RT\\n(SCHED_FIFO) kthread which cannot be starved by either fair or ext class\\ntasks. scx_enable() lazily creates the kthread on first use and passes the\\nops pointer through a struct scx_enable_cmd containing the kthread_work,\\nthen synchronously waits for completion.\\n\\nThe workfn runs on a different kthread from sch-\u003ehelper (which runs\\ndisable_work), so it can safely flush disable_work on the error path\\nwithout deadlock.\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/05ab9ec5dc24f234e0a2fecf3e6ff937c68f7d81\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/b06ccbabe2506fd70b9167a644978b049150224a\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/c44198f25fdfecc0ec0fe366bf8a47fe17d8e229\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/e0b14bf06393be137d3efb6a3b7cd5b4b9810a6b\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




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.