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CVE-2026-72398 (GCVE-0-2026-72398)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:56 – Updated: 2026-08-17 05:43
VLAI
Title
sctp: add INIT verification after cookie unpacking
Summary
In the Linux kernel, the following vulnerability has been resolved: sctp: add INIT verification after cookie unpacking In SCTP handshake, the INIT chunk is initially processed by the server and embedded into the cookie carried in INIT-ACK. The client then returns this cookie via COOKIE-ECHO, where the server unpacks it and reconstructs the original INIT chunk. When cookie authentication is enabled, the cookie contents are protected against tampering, so reusing the unpacked INIT without re-verification is safe. However, when cookie authentication is disabled, the reconstructed INIT can no longer be trusted. In this case, the INIT must be explicitly validated after unpacking to avoid processing potentially tampered data. Add sctp_verify_init() checks after cookie unpacking in COOKIE-ECHO processing paths (sctp_sf_do_5_1D_ce() and sctp_sf_do_5_2_4_dupcook()) when cookie_auth_enable is disabled. On failure, the new association is freed and the packet is discarded. Also tighten cookie validation in sctp_unpack_cookie() by verifying the embedded chunk type is SCTP_CID_INIT before treating it as an INIT chunk. Finally, update sctp_verify_init() to validate parameter bounds using the actual embedded INIT length instead of chunk->chunk_end, since the INIT stored in COOKIE-ECHO may not span the entire chunk buffer.
Severity
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < bca3100f550281c2f2418652338bced3b35af0e6 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 062bcbf8d1f1051fdeb20b94920031b0e2cb95a2 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 414c5447fe6a200613dd46d7fdc8454622076cb1 (git)
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Linux Linux Affected: 2.6.12
Unaffected: 0 , < 2.6.12 (semver)
Unaffected: 6.18.40 , ≤ 6.18.* (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/sctp/sm_make_chunk.c",
            "net/sctp/sm_statefuns.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "versionType": "git"
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "2.6.12"
            },
            {
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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              "version": "6.18.40",
              "versionType": "semver"
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              "version": "7.1.5",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
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        }
      ],
      "cpeApplicability": [
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          "nodes": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.40",
                  "versionStartIncluding": "2.6.12",
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              "operator": "OR"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsctp: add INIT verification after cookie unpacking\n\nIn SCTP handshake, the INIT chunk is initially processed by the server\nand embedded into the cookie carried in INIT-ACK. The client then\nreturns this cookie via COOKIE-ECHO, where the server unpacks it and\nreconstructs the original INIT chunk.\n\nWhen cookie authentication is enabled, the cookie contents are protected\nagainst tampering, so reusing the unpacked INIT without re-verification\nis safe.\n\nHowever, when cookie authentication is disabled, the reconstructed INIT\ncan no longer be trusted. In this case, the INIT must be explicitly\nvalidated after unpacking to avoid processing potentially tampered data.\n\nAdd sctp_verify_init() checks after cookie unpacking in COOKIE-ECHO\nprocessing paths (sctp_sf_do_5_1D_ce() and sctp_sf_do_5_2_4_dupcook())\nwhen cookie_auth_enable is disabled. On failure, the new association is\nfreed and the packet is discarded.\n\nAlso tighten cookie validation in sctp_unpack_cookie() by verifying the\nembedded chunk type is SCTP_CID_INIT before treating it as an INIT\nchunk.\n\nFinally, update sctp_verify_init() to validate parameter bounds using\nthe actual embedded INIT length instead of chunk-\u003echunk_end, since the\nINIT stored in COOKIE-ECHO may not span the entire chunk buffer."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.8,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The bug is reached when a remote peer sends SCTP COOKIE-ECHO packets to a listening endpoint; packets enter through sctp_rcv()/IPv4/IPv6 SCTP handlers and are dispatched to COOKIE-ECHO state handlers without any local access requirement.\nAC:L - On deployments with SCTP cookie authentication disabled (supported via cookie_hmac_alg=none), an attacker can complete INIT/INIT-ACK, tamper with the embedded INIT in the returned cookie, and reliably trigger the vulnerable path with crafted COOKIE-ECHO traffic.\nPR:N - Exploitation is pre-authentication SCTP handshake processing on a listening server; the attacker only needs network reachability to the SCTP port and does not need local privileges, credentials, or CAP_NET_ADMIN on the target.\nUI:N - No victim user action is required beyond operating an SCTP listener; exploitation is achieved solely by sending attacker-crafted SCTP handshake packets over the network.\nS:U - The vulnerability affects the Linux kernel SCTP stack on the target host and does not cross a separate security boundary such as guest-to-host VM escape, container sandbox escape, or IOMMU/DMA isolation bypass.\nC:H - Without sctp_verify_init() and with incorrect INIT parameter bound checks, attacker-controlled embedded INIT lengths/types can drive sctp_walk_params() and kmemdup() beyond valid cookie data, enabling out-of-bounds kernel memory reads.\nI:H - Tampered or type-confused embedded INIT data is parsed into association/peer state via sctp_process_init() without full validation, causing kernel memory-safety corruption that can modify association structures and plausibly be leveraged for stronger write primitives.\nA:H - Malformed embedded INIT processing during COOKIE-ECHO handling can trigger kernel faults, KASAN/oops conditions, allocation failures, or repeated crashes of SCTP input processing, causing high availability impact on internet-facing SCTP services."
            }
          ]
        }
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      "providerMetadata": {
        "dateUpdated": "2026-08-17T05:43:40.793Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/bca3100f550281c2f2418652338bced3b35af0e6"
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          "url": "https://git.kernel.org/stable/c/062bcbf8d1f1051fdeb20b94920031b0e2cb95a2"
        },
        {
          "url": "https://git.kernel.org/stable/c/414c5447fe6a200613dd46d7fdc8454622076cb1"
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      ],
      "title": "sctp: add INIT verification after cookie unpacking",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-72398",
    "datePublished": "2026-08-15T05:56:24.306Z",
    "dateReserved": "2026-08-09T03:40:39.925Z",
    "dateUpdated": "2026-08-17T05:43:40.793Z",
    "state": "PUBLISHED"
  },
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  "dataVersion": "5.2",
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    "epss": {
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      "date": "2026-09-11",
      "epss": "0.00704",
      "percentile": "0.51261"
    },
    "microsoft_vex": {
      "current_release_date": "2026-08-23T14:43:16.000Z",
      "cve": "CVE-2026-72398",
      "id": "msrc_CVE-2026-72398",
      "initial_release_date": "2026-08-23T14:43:16.000Z",
      "product_status:known_affected": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "sctp: add INIT verification after cookie unpacking",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-72398.json",
      "version": "1"
    },
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-19T17:41:54+00:00",
      "cve": "CVE-2026-72398",
      "id": "CVE-2026-72398",
      "initial_release_date": "2026-08-15T00:00:00+00:00",
      "product_status:known_affected": "274",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: sctp: add INIT verification after cookie unpacking",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72398.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "important",
      "current_release_date": "2026-08-31T16:25:50Z",
      "cve": "CVE-2026-72398",
      "id": "CVE-2026-72398",
      "initial_release_date": "2026-08-25T01:21:53Z",
      "product_status:known_affected": "123",
      "product_status:known_not_affected": "239",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-72398",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-72398.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.