CVE-2026-98530 (GCVE-0-2026-98530)

Vulnerability from cvelistv5 – Published: 2026-10-18 15:17 – Updated: 2026-10-19 09:21
VLAI
Title
kprobes: Fix permanent hang when flushing the kprobe optimizer
Summary
In the Linux kernel, the following vulnerability has been resolved: kprobes: Fix permanent hang when flushing the kprobe optimizer Writing 0 to /proc/sys/debug/kprobes-optimization while a kprobe is jump-optimized never returns. The writer sleeps in D state forever with kprobe_sysctl_mutex held, so any later read or write of that sysctl hangs as well. For example, with vfs_read+9 as an optimizable address in this build: # cd /sys/kernel/tracing # echo 'p:myprobe vfs_read+9' >> kprobe_events # echo 1 > events/kprobes/myprobe/enable # # wait until /sys/kernel/debug/kprobes/list shows [OPTIMIZED] # echo 0 > /proc/sys/debug/kprobes-optimization INFO: task sh:246 blocked for more than 10 seconds. Call Trace: <TASK> __schedule+0x1176/0x4f70 schedule+0xdc/0x2c0 schedule_timeout+0x17b/0x260 wait_for_completion+0x173/0x3c0 wait_for_kprobe_optimizer_locked+0xbc/0x130 proc_kprobes_optimization_handler+0x156/0x1b0 proc_sys_call_handler+0x324/0x490 vfs_write+0x52d/0xfe0 ksys_write+0xff/0x200 do_syscall_64+0x106/0x630 entry_SYSCALL_64_after_hwframe+0x77/0x7f </TASK> ... INFO: task cat:265 is blocked on a mutex likely owned by task sh:246. wait_for_kprobe_optimizer_locked() reinitializes optimizer_completion, asks the optimizer thread to flush and sleeps in wait_for_completion(). The thread drains the (un)optimizing lists, but calls complete() only if completion_done() is true, i.e. if the completion is already done, which never happens while someone waits. disarm_all_kprobes() and kprobe_trace_self_tests_init() wait the same way. Calling complete() unconditionally would not be enough: the waiter drops kprobe_mutex while it sleeps, and nothing else serializes the sysctl handler against the debugfs "enabled" file. A second flusher that still finds the lists non-empty, e.g. because a disabled probe is queued for unoptimizing, reinitializes the completion under the first: sysctl write debugfs "enabled" write unoptimize_all_kprobes() wait_for_kprobe_optimizer_locked() init_completion(c) mutex_unlock(&kprobe_mutex) wait_for_completion(c) disarm_all_kprobes() wait_for_kprobe_optimizer_locked() init_completion(c) // c->wait is reset, the first // waiter is off the queue mutex_unlock(&kprobe_mutex) wait_for_completion(c) kprobe_optimizer() complete(c) // wakes the debugfs writer only where c is &optimizer_completion. Lining up the two writes during an optimizer pass loses the sysctl writer this way. Replace the completion with a counter of optimizer passes, bumped at the end of each pass and signalled with wake_up_var_locked(), both under kprobe_mutex. A flusher samples the count and waits with wait_var_event_mutex(), which drops kprobe_mutex only while sleeping, so a new count means a whole pass ran in the meantime. Nothing is reinitialized, so several flushers can sleep in the wait at once.
Severity
No CVSS data available.
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6641 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 73c12f209462d1712c5f55f3021a1b65b2e084c3 , < f05a01fc7d4f731b4c100d2aef1e85ad77728862 (git)
Affected: 73c12f209462d1712c5f55f3021a1b65b2e084c3 , < 5bfa9f1a9dcb6ecb607adbc1c0226605c972935b (git)
guessed Create a notification for this product.
Linux Linux Affected: 7.0
Unaffected: 0 , < 7.0 (semver)
Unaffected: 7.2.9 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/kprobes.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "f05a01fc7d4f731b4c100d2aef1e85ad77728862",
              "status": "affected",
              "version": "73c12f209462d1712c5f55f3021a1b65b2e084c3",
              "versionType": "git"
            },
            {
              "lessThan": "5bfa9f1a9dcb6ecb607adbc1c0226605c972935b",
              "status": "affected",
              "version": "73c12f209462d1712c5f55f3021a1b65b2e084c3",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "kernel/kprobes.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.0"
            },
            {
              "lessThan": "7.0",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.9",
                  "versionStartIncluding": "7.0",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "7.0",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nkprobes: Fix permanent hang when flushing the kprobe optimizer\n\nWriting 0 to /proc/sys/debug/kprobes-optimization while a kprobe is\njump-optimized never returns. The writer sleeps in D state forever with\nkprobe_sysctl_mutex held, so any later read or write of that sysctl\nhangs as well. For example, with vfs_read+9 as an optimizable address\nin this build:\n\n  # cd /sys/kernel/tracing\n  # echo \u0027p:myprobe vfs_read+9\u0027 \u003e\u003e kprobe_events\n  # echo 1 \u003e events/kprobes/myprobe/enable\n  # # wait until /sys/kernel/debug/kprobes/list shows [OPTIMIZED]\n  # echo 0 \u003e /proc/sys/debug/kprobes-optimization\n\n  INFO: task sh:246 blocked for more than 10 seconds.\n  Call Trace:\n   \u003cTASK\u003e\n   __schedule+0x1176/0x4f70\n   schedule+0xdc/0x2c0\n   schedule_timeout+0x17b/0x260\n   wait_for_completion+0x173/0x3c0\n   wait_for_kprobe_optimizer_locked+0xbc/0x130\n   proc_kprobes_optimization_handler+0x156/0x1b0\n   proc_sys_call_handler+0x324/0x490\n   vfs_write+0x52d/0xfe0\n   ksys_write+0xff/0x200\n   do_syscall_64+0x106/0x630\n   entry_SYSCALL_64_after_hwframe+0x77/0x7f\n   \u003c/TASK\u003e\n  ...\n  INFO: task cat:265 is blocked on a mutex likely owned by task sh:246.\n\nwait_for_kprobe_optimizer_locked() reinitializes optimizer_completion,\nasks the optimizer thread to flush and sleeps in wait_for_completion().\nThe thread drains the (un)optimizing lists, but calls complete() only\nif completion_done() is true, i.e. if the completion is already done,\nwhich never happens while someone waits. disarm_all_kprobes() and\nkprobe_trace_self_tests_init() wait the same way.\n\nCalling complete() unconditionally would not be enough: the waiter\ndrops kprobe_mutex while it sleeps, and nothing else serializes the\nsysctl handler against the debugfs \"enabled\" file. A second flusher\nthat still finds the lists non-empty, e.g. because a disabled probe is\nqueued for unoptimizing, reinitializes the completion under the first:\n\n  sysctl write                      debugfs \"enabled\" write\n  unoptimize_all_kprobes()\n    wait_for_kprobe_optimizer_locked()\n      init_completion(c)\n      mutex_unlock(\u0026kprobe_mutex)\n      wait_for_completion(c)\n                                    disarm_all_kprobes()\n                                      wait_for_kprobe_optimizer_locked()\n                                        init_completion(c)\n                                          // c-\u003ewait is reset, the first\n                                          // waiter is off the queue\n                                        mutex_unlock(\u0026kprobe_mutex)\n                                        wait_for_completion(c)\n  kprobe_optimizer()\n    complete(c)\n      // wakes the debugfs writer only\n\nwhere c is \u0026optimizer_completion. Lining up the two writes during an\noptimizer pass loses the sysctl writer this way.\n\nReplace the completion with a counter of optimizer passes, bumped at the\nend of each pass and signalled with wake_up_var_locked(), both under\nkprobe_mutex. A flusher samples the count and waits with\nwait_var_event_mutex(), which drops kprobe_mutex only while sleeping, so\na new count means a whole pass ran in the meantime. Nothing is\nreinitialized, so several flushers can sleep in the wait at once."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:21:13.045Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/f05a01fc7d4f731b4c100d2aef1e85ad77728862"
        },
        {
          "url": "https://git.kernel.org/stable/c/5bfa9f1a9dcb6ecb607adbc1c0226605c972935b"
        }
      ],
      "title": "kprobes: Fix permanent hang when flushing the kprobe optimizer",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98530",
    "datePublished": "2026-10-18T15:17:48.670Z",
    "dateReserved": "2026-09-25T10:25:14.355Z",
    "dateUpdated": "2026-10-19T09:21:13.045Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-98530",
      "date": "2026-11-11",
      "epss": "0.00198",
      "percentile": "0.09675"
    },
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "defaultStatus": "unaffected",
                "product": "Linux",
                "programFiles": [
                  "kernel/kprobes.c"
                ],
                "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                "vendor": "Linux",
                "versions": [
                  {
                    "lessThan": "f05a01fc7d4f731b4c100d2aef1e85ad77728862",
                    "status": "affected",
                    "version": "73c12f209462d1712c5f55f3021a1b65b2e084c3",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "5bfa9f1a9dcb6ecb607adbc1c0226605c972935b",
                    "status": "affected",
                    "version": "73c12f209462d1712c5f55f3021a1b65b2e084c3",
                    "versionType": "git"
                  }
                ]
              },
              {
                "defaultStatus": "affected",
                "product": "Linux",
                "programFiles": [
                  "kernel/kprobes.c"
                ],
                "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                "vendor": "Linux",
                "versions": [
                  {
                    "status": "affected",
                    "version": "7.0"
                  },
                  {
                    "lessThan": "7.0",
                    "status": "unaffected",
                    "version": "0",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "7.2.*",
                    "status": "unaffected",
                    "version": "7.2.9",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "*",
                    "status": "unaffected",
                    "version": "7.3",
                    "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\nkprobes: Fix permanent hang when flushing the kprobe optimizer\n\nWriting 0 to /proc/sys/debug/kprobes-optimization while a kprobe is\njump-optimized never returns. The writer sleeps in D state forever with\nkprobe_sysctl_mutex held, so any later read or write of that sysctl\nhangs as well. For example, with vfs_read+9 as an optimizable address\nin this build:\n\n  # cd /sys/kernel/tracing\n  # echo \u0027p:myprobe vfs_read+9\u0027 \u003e\u003e kprobe_events\n  # echo 1 \u003e events/kprobes/myprobe/enable\n  # # wait until /sys/kernel/debug/kprobes/list shows [OPTIMIZED]\n  # echo 0 \u003e /proc/sys/debug/kprobes-optimization\n\n  INFO: task sh:246 blocked for more than 10 seconds.\n  Call Trace:\n   \u003cTASK\u003e\n   __schedule+0x1176/0x4f70\n   schedule+0xdc/0x2c0\n   schedule_timeout+0x17b/0x260\n   wait_for_completion+0x173/0x3c0\n   wait_for_kprobe_optimizer_locked+0xbc/0x130\n   proc_kprobes_optimization_handler+0x156/0x1b0\n   proc_sys_call_handler+0x324/0x490\n   vfs_write+0x52d/0xfe0\n   ksys_write+0xff/0x200\n   do_syscall_64+0x106/0x630\n   entry_SYSCALL_64_after_hwframe+0x77/0x7f\n   \u003c/TASK\u003e\n  ...\n  INFO: task cat:265 is blocked on a mutex likely owned by task sh:246.\n\nwait_for_kprobe_optimizer_locked() reinitializes optimizer_completion,\nasks the optimizer thread to flush and sleeps in wait_for_completion().\nThe thread drains the (un)optimizing lists, but calls complete() only\nif completion_done() is true, i.e. if the completion is already done,\nwhich never happens while someone waits. disarm_all_kprobes() and\nkprobe_trace_self_tests_init() wait the same way.\n\nCalling complete() unconditionally would not be enough: the waiter\ndrops kprobe_mutex while it sleeps, and nothing else serializes the\nsysctl handler against the debugfs \"enabled\" file. A second flusher\nthat still finds the lists non-empty, e.g. because a disabled probe is\nqueued for unoptimizing, reinitializes the completion under the first:\n\n  sysctl write                      debugfs \"enabled\" write\n  unoptimize_all_kprobes()\n    wait_for_kprobe_optimizer_locked()\n      init_completion(c)\n      mutex_unlock(\u0026kprobe_mutex)\n      wait_for_completion(c)\n                                    disarm_all_kprobes()\n                                      wait_for_kprobe_optimizer_locked()\n                                        init_completion(c)\n                                          // c-\u003ewait is reset, the first\n                                          // waiter is off the queue\n                                        mutex_unlock(\u0026kprobe_mutex)\n                                        wait_for_completion(c)\n  kprobe_optimizer()\n    complete(c)\n      // wakes the debugfs writer only\n\nwhere c is \u0026optimizer_completion. Lining up the two writes during an\noptimizer pass loses the sysctl writer this way.\n\nReplace the completion with a counter of optimizer passes, bumped at the\nend of each pass and signalled with wake_up_var_locked(), both under\nkprobe_mutex. A flusher samples the count and waits with\nwait_var_event_mutex(), which drops kprobe_mutex only while sleeping, so\na new count means a whole pass ran in the meantime. Nothing is\nreinitialized, so several flushers can sleep in the wait at once."
          }
        ],
        "id": "CVE-2026-98530",
        "lastModified": "2026-10-19T10:19:08.410",
        "metrics": {},
        "published": "2026-10-18T16:17:04.530",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/5bfa9f1a9dcb6ecb607adbc1c0226605c972935b"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/f05a01fc7d4f731b4c100d2aef1e85ad77728862"
          }
        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-11-07T11:30:31+00:00",
      "cve": "CVE-2026-98530",
      "id": "CVE-2026-98530",
      "initial_release_date": "2026-10-18T00:00:00+00:00",
      "product_status:known_affected": "14",
      "product_status:known_not_affected": "189",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: kprobes: Fix permanent hang when flushing the kprobe optimizer",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-98530.json",
      "version": "3"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.

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.
Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

JSON
How durations are calculated

Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

Loading timeline…




    Related by attack behaviour

    Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.