FKIE_CVE-2026-98548

Vulnerability from fkie_nvd - Published: 2026-10-18 16:17 - Updated: 2026-10-24 14:16
Severity
9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: sctp: discard the rest of the packet on a stale-cookie error When an association is in COOKIE-ECHOED state and the peer sends a bundled [ERROR(Stale Cookie)][DATA] packet from one of its non-primary addresses, processing the ERROR chunk takes the non-fatal stale-cookie retry path sctp_sf_do_5_2_6_stale(), which queues SCTP_CMD_DEL_NON_PRIMARY while keeping the association alive. sctp_cmd_del_non_primary() removes every non-primary transport - including the very transport this packet arrived on, which is still referenced by the receive lookup and shared by all chunks of the packet via chunk->transport. sctp_assoc_rm_peer() does redirect asoc->peer.last_data_from away from the removed transport, but right afterwards the bundled DATA chunk makes sctp_assoc_bh_rcv() re-register asoc->peer.last_data_from = chunk->transport unconditionally, undoing the redirection with the just-removed transport. Once the packet is done, the receive reference is dropped and the transport is RCU-freed, while the surviving association keeps the dangling last_data_from. A later FWD-TSN (or the delayed SACK timer) makes sctp_gen_sack() dereference it (->param_flags and friends), and sctp_make_sack()/sctp_outq_select_transport() may write to the freed object and link it into the live transport list. This is a use-after-free triggerable by any malicious SCTP peer (or a local unprivileged user acting as one) with no capabilities required: BUG: KASAN: slab-use-after-free in sctp_do_sm+0x498a/0x5660 Read of size 4 at addr ffff88800e1e356c by task poc/115 Call Trace: sctp_do_sm <- sctp_assoc_bh_rcv <- sctp_inq_push <- sctp_rcv <- ip_protocol_deliver_rcu <- ip_rcv Allocated: sctp_transport_new <- sctp_assoc_add_peer <- sctp_process_init (INIT-ACK processing) Freed: kfree <- sctp_transport_destroy_rcu <- rcu_core (call_rcu queued by sctp_transport_put at end of sctp_rcv) The buggy address is located 364 bytes inside of freed 1024-byte region [ffff88800e1e3400, ffff88800e1e3800), cache kmalloc-1k Note that commit 03a9d10ecf71 ("sctp: drop a chunk if its transport was removed") only covers the window between the receive lookup and the chunk processing (e.g. an ASCONF DEL-IP racing the socket backlog); here the transport is removed *while* the packet is being processed, by an earlier chunk of the same packet, so the drop in sctp_inq_push() does not reach this path. Verified with the bundled [ERROR(Stale Cookie)][DATA] + FWD-TSN reproducer: the KASAN report above still fires with that commit applied, and is gone with this patch on top. Fix it by discarding the rest of the packet on this path, as suggested by Xin. After the stale-cookie ERROR has sent the association back to COOKIE-WAIT and removed the non-primary transports, the remaining chunks of the packet can only run against the restarted handshake while referencing the removed arrival transport through chunk->transport: besides the last_data_from registration above, sctp_cmd_setup_t2() and the sctp_make_*() reply builders would also copy that pointer into association-lifetime state that sctp_assoc_rm_peer() has already sanitized. Let the peer retransmit them, in line with what sctp_inq_push() does for chunks whose transport was removed before processing.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/1cd246b214dc9acf4e2f11d58c035e1e672fe7d2
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/4498467a8af06cfa3d71cb04bd7c4170dec8f449
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6df536c5acbc0abd6f119d02e24f4a2ed97707f4
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/854c053c71459f8db7ef07db9cfa4eec5f5206f2
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/965e21ea16acb394d5e5801998ca9b0adc669665
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/c0af3fd150fdc43821df3bb77e5ec74faf4dfc7a
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/d68c9287b3ca0d6faadc61fbcb18d1a6b5493321
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/ec23855274a73906b02f0d124fefd9cb3c008b1d
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/sctp/sm_statefuns.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "c0af3fd150fdc43821df3bb77e5ec74faf4dfc7a",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            },
            {
              "lessThan": "854c053c71459f8db7ef07db9cfa4eec5f5206f2",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            },
            {
              "lessThan": "965e21ea16acb394d5e5801998ca9b0adc669665",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            },
            {
              "lessThan": "1cd246b214dc9acf4e2f11d58c035e1e672fe7d2",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            },
            {
              "lessThan": "d68c9287b3ca0d6faadc61fbcb18d1a6b5493321",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            },
            {
              "lessThan": "ec23855274a73906b02f0d124fefd9cb3c008b1d",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            },
            {
              "lessThan": "6df536c5acbc0abd6f119d02e24f4a2ed97707f4",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            },
            {
              "lessThan": "4498467a8af06cfa3d71cb04bd7c4170dec8f449",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/sctp/sm_statefuns.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "2.6.12"
            },
            {
              "lessThan": "2.6.12",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.271",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.222",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.189",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.158",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.112",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.55",
              "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\nsctp: discard the rest of the packet on a stale-cookie error\n\nWhen an association is in COOKIE-ECHOED state and the peer sends a\nbundled [ERROR(Stale Cookie)][DATA] packet from one of its non-primary\naddresses, processing the ERROR chunk takes the non-fatal stale-cookie\nretry path sctp_sf_do_5_2_6_stale(), which queues\nSCTP_CMD_DEL_NON_PRIMARY while keeping the association alive.\nsctp_cmd_del_non_primary() removes every non-primary transport -\nincluding the very transport this packet arrived on, which is still\nreferenced by the receive lookup and shared by all chunks of the\npacket via chunk-\u003etransport.\n\nsctp_assoc_rm_peer() does redirect asoc-\u003epeer.last_data_from away from\nthe removed transport, but right afterwards the bundled DATA chunk\nmakes sctp_assoc_bh_rcv() re-register\nasoc-\u003epeer.last_data_from = chunk-\u003etransport unconditionally, undoing\nthe redirection with the just-removed transport.\n\nOnce the packet is done, the receive reference is dropped and the\ntransport is RCU-freed, while the surviving association keeps the\ndangling last_data_from.  A later FWD-TSN (or the delayed SACK timer)\nmakes sctp_gen_sack() dereference it (-\u003eparam_flags and friends), and\nsctp_make_sack()/sctp_outq_select_transport() may write to the freed\nobject and link it into the live transport list.  This is a\nuse-after-free triggerable by any malicious SCTP peer (or a local\nunprivileged user acting as one) with no capabilities required:\n\n  BUG: KASAN: slab-use-after-free in sctp_do_sm+0x498a/0x5660\n  Read of size 4 at addr ffff88800e1e356c by task poc/115\n  Call Trace: sctp_do_sm \u003c- sctp_assoc_bh_rcv \u003c- sctp_inq_push \u003c-\n              sctp_rcv \u003c- ip_protocol_deliver_rcu \u003c- ip_rcv\n  Allocated: sctp_transport_new \u003c- sctp_assoc_add_peer \u003c-\n             sctp_process_init (INIT-ACK processing)\n  Freed: kfree \u003c- sctp_transport_destroy_rcu \u003c- rcu_core\n         (call_rcu queued by sctp_transport_put at end of sctp_rcv)\n  The buggy address is located 364 bytes inside of freed 1024-byte\n  region [ffff88800e1e3400, ffff88800e1e3800), cache kmalloc-1k\n\nNote that commit 03a9d10ecf71 (\"sctp: drop a chunk if its transport\nwas removed\") only covers the window between the receive lookup and\nthe chunk processing (e.g. an ASCONF DEL-IP racing the socket backlog);\nhere the transport is removed *while* the packet is being processed,\nby an earlier chunk of the same packet, so the drop in sctp_inq_push()\ndoes not reach this path.  Verified with the bundled [ERROR(Stale\nCookie)][DATA] + FWD-TSN reproducer: the KASAN report above still\nfires with that commit applied, and is gone with this patch on top.\n\nFix it by discarding the rest of the packet on this path, as suggested\nby Xin.  After the stale-cookie ERROR has sent the association back to\nCOOKIE-WAIT and removed the non-primary transports, the remaining\nchunks of the packet can only run against the restarted handshake\nwhile referencing the removed arrival transport through\nchunk-\u003etransport: besides the last_data_from registration above,\nsctp_cmd_setup_t2() and the sctp_make_*() reply builders would also\ncopy that pointer into association-lifetime state that\nsctp_assoc_rm_peer() has already sanitized.  Let the peer retransmit\nthem, in line with what sctp_inq_push() does for chunks whose\ntransport was removed before processing."
    }
  ],
  "id": "CVE-2026-98548",
  "lastModified": "2026-10-24T14:16:46.943",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 9.8,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-10-18T16:17:06.767",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/1cd246b214dc9acf4e2f11d58c035e1e672fe7d2"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/4498467a8af06cfa3d71cb04bd7c4170dec8f449"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/6df536c5acbc0abd6f119d02e24f4a2ed97707f4"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/854c053c71459f8db7ef07db9cfa4eec5f5206f2"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/965e21ea16acb394d5e5801998ca9b0adc669665"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/c0af3fd150fdc43821df3bb77e5ec74faf4dfc7a"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/d68c9287b3ca0d6faadc61fbcb18d1a6b5493321"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/ec23855274a73906b02f0d124fefd9cb3c008b1d"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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