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CVE-2026-98130

📛 CVE Title

sctp: fix a TOCTOU race in SCTP_CMD_TIMER_START

Description

In the Linux kernel, the following vulnerability has been resolved: sctp: fix a TOCTOU race in SCTP_CMD_TIMER_START The SCTP_CMD_TIMER_START handler checks timer_pending() before calling timer_reduce(). The timer can expire and detach between these operations, causing timer_reduce() to rearm the timer without taking the association reference required for the newly armed timer. The timer callback later unconditionally drops its association reference, which can leave the association reference count unbalanced and result in use-after-free during association teardown. Use the return value of timer_reduce() to determine whether the timer was actually armed. Take the association reference only when timer_reduce() successfully starts a new timer, closing the race between checking the timer state and rearming it. This issue was reported by Nico Yip (@_cyeaa_) working with TrendAI Zero Day Initiative.

Overview

State
PUBLISHED
Assigner (CNA)
Linux
CVSS severity
HIGH
CVSS score
CVSS 8.1 / 10 8.1 8.1 / 10
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Effective score
8.1 / 10 HIGH source: CNA overview
CWE(s)
—
Reserved
2026-09-25
Published
2026-09-25 10:36 UTC
Last updated
2026-09-25 14:42 UTC
Source
https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/98xxx/CVE-2026-98130.json
Linked Threat
CVE-2026-98130 — sctp: fix a TOCTOU race in SCTP_CMD_TIMER_START

NVD triage scoring NVD CVE 2.0

Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.

NVD published
2026-09-25 11:17:44 UTC
NVD last modified
2026-09-25 15:18:06 UTC
NVD CVSS v3.1
CVSS 8.1 / 10 8.1 8.1 / 10 HIGH source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Exploitability subscore
2.2 / 10
Impact subscore
5.9 / 10

NVD / KEV / EPSS data refreshed 2026-09-26 04:22 UTC. Re-run the 🛰 Backfill from NVD button above to refresh.

Affected products (2)

VendorProductVersionsPlatforms
Linux Linux 20a785aa52c82246055a089e55df9dac47d67da1 (affected), 20a785aa52c82246055a089e55df9dac47d67da1 (affected), 20a785aa52c82246055a089e55df9dac47d67da1 (affected), 20a785aa52c82246055a089e55df9dac47d67da1 (affected), 9c0a4652f750afe3b4468cbcd9335b244ce2facd (affected), 70989e501fbce502198d82da88358ce453575a05 (affected), 085bb270b4b1168c93afb37bbafc881207d15443 (affected), 4.19.126 (affected), 5.4.44 (affected), 5.6.16 (affected) —
Linux Linux 5.7 (affected), 0 (unaffected), 6.12.111 (unaffected), 6.18.53 (unaffected), 7.2.7 (unaffected), 7.3-rc2 (unaffected) —

Vendor references (4)

References embedded in the original CVE record by the assigning CNA.

Web references (0)

DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.

No web references attached yet.

NVD-tagged references (4)

Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.

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Raw JSON

The full cvelistV5 record. Download as CVE-2026-98130.json.

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/sctp/sm_sideeffect.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
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              "status": "affected",
              "version": "20a785aa52c82246055a089e55df9dac47d67da1",
              "versionType": "git"
            },
            {
              "lessThan": "00b841bac10230c557be6b38efc48508198fe23e",
              "status": "affected",
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              "versionType": "git"
            },
            {
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              "versionType": "git"
            },
            {
              "lessThan": "2188569e7e1b0bc3f3b557dc97ab7a02befc11c8",
              "status": "affected",
              "version": "20a785aa52c82246055a089e55df9dac47d67da1",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "9c0a4652f750afe3b4468cbcd9335b244ce2facd",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "70989e501fbce502198d82da88358ce453575a05",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "085bb270b4b1168c93afb37bbafc881207d15443",
              "versionType": "git"
            },
            {
              "lessThan": "4.20",
              "status": "affected",
              "version": "4.19.126",
              "versionType": "semver"
            },
            {
              "lessThan": "5.5",
              "status": "affected",
              "version": "5.4.44",
              "versionType": "semver"
            },
            {
              "lessThan": "5.7",
              "status": "affected",
              "version": "5.6.16",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
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          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.7"
            },
            {
              "lessThan": "5.7",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.111",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.53",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.7",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.111",
                  "versionStartIncluding": "5.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.53",
                  "versionStartIncluding": "5.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.7",
                  "versionStartIncluding": "5.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3-rc2",
                  "versionStartIncluding": "5.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "4.19.126",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "5.4.44",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "5.6.16",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsctp: fix a TOCTOU race in SCTP_CMD_TIMER_START\n\nThe SCTP_CMD_TIMER_START handler checks timer_pending() before calling\ntimer_reduce(). The timer can expire and detach between these operations,\ncausing timer_reduce() to rearm the timer without taking the association\nreference required for the newly armed timer.\n\nThe timer callback later unconditionally drops its association reference,\nwhich can leave the association reference count unbalanced and result in\nuse-after-free during association teardown.\n\nUse the return value of timer_reduce() to determine whether the timer was\nactually armed. Take the association reference only when timer_reduce()\nsuccessfully starts a new timer, closing the race between checking the\ntimer state and rearming it.\n\nThis issue was reported by Nico Yip (@_cyeaa_) working with TrendAI Zero\nDay Initiative."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.1,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - A remote SCTP peer's restart COOKIE-ECHO goes through sctp_sf_do_5_2_4_dupcook()/sctp_sf_do_dupcook_a() in SHUTDOWN_SENT and on to sctp_sf_do_9_2_start_shutdown(). That queues SCTP_CMD_TIMER_START for T2-shutdown while T2 is already armed, which reaches the racy timer_pending()/timer_reduce() pair in sctp_cmd_interpreter(). SCTP runs over routable IP.\nAC:H - The peer must time its COOKIE-ECHO so that T2 expires on another CPU in the window between timer_pending() and timer_reduce(), which is two adjacent statements. The attacker can retry by timing packets around T2 retransmissions, but cannot control when the kernel timer fires relative to softirq processing. The target association must also be in SHUTDOWN_SENT with its socket closing.\nPR:N - SCTP association setup and the restart COOKIE-ECHO path in sctp_sf_do_dupcook_a() need no authentication. The attacker is just the unauthenticated peer of the association.\nUI:N - No victim action is needed beyond the SCTP service normally closing an association, which puts it in SHUTDOWN_SENT. The attacker sends all the triggering packets.\nS:U - The corruption is confined to the kernel's own sctp_association object. No security boundary such as a VM or IOMMU is crossed.\nC:H - Re-arming the timer without sctp_association_hold() lets sctp_generate_timeout_event() call sctp_association_put() one time too many. The association is then freed while still referenced, a use-after-free of a large slab object whose reclaimed contents can be used to leak kernel memory.\nI:H - The freed sctp_association holds function-relevant state such as timers, transports and the outqueue. Later timer callbacks and teardown writes into reclaimed memory give a write primitive that could be used to hijack control flow.\nA:H - The unbalanced refcount causes a refcount underflow or use-after-free during association teardown or a later timer callback, crashing the kernel."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-25T14:42:10.732Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/e42ba56281ca3ae2dcb3558bebee9a1c9a4831d9"
        },
        {
          "url": "https://git.kernel.org/stable/c/00b841bac10230c557be6b38efc48508198fe23e"
        },
        {
          "url": "https://git.kernel.org/stable/c/3d698d1e6c8bc41e3e1707777a016f1bdd07842d"
        },
        {
          "url": "https://git.kernel.org/stable/c/2188569e7e1b0bc3f3b557dc97ab7a02befc11c8"
        }
      ],
      "title": "sctp: fix a TOCTOU race in SCTP_CMD_TIMER_START",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98130",
    "datePublished": "2026-09-25T10:36:10.243Z",
    "dateReserved": "2026-09-25T10:25:14.318Z",
    "dateUpdated": "2026-09-25T14:42:10.732Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}