Vulnerability-Lookup

OPENSUSE-SU-2026:20252-1

Vulnerability from csaf_opensuse - Published: 2026-02-18 16:14 - Updated: 2026-02-18 16:14

Summary

Security update for the Linux Kernel (Live Patch 1 for SUSE Linux Enterprise 16)

Severity

Important

Notes

Title of the patch: Security update for the Linux Kernel (Live Patch 1 for SUSE Linux Enterprise 16)

Description of the patch: This update for the SUSE Linux Enterprise kernel 6.12.0-160000.6.1 fixes one security issue The following security issue was fixed: - CVE-2025-40186: tcp: Don't call reqsk_fastopen_remove() in tcp_conn_request() (bsc#1253439).

Patchnames: openSUSE-Leap-16.0-297

CVE-2025-40186

7 (High)


                
                  CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

Recommended 3 products

Product	Version	Remediation
Unresolved product id: openSUSE Leap 16.0:kernel-livepatch-6_12_0-160000_6-default-4-160000.1.1.ppc64le	—	Vendor Fix
Unresolved product id: openSUSE Leap 16.0:kernel-livepatch-6_12_0-160000_6-default-4-160000.1.1.s390x	—	Vendor Fix
Unresolved product id: openSUSE Leap 16.0:kernel-livepatch-6_12_0-160000_6-default-4-160000.1.1.x86_64	—	Vendor Fix

Threats

Impact important

References

7 references

URL	Category
https://www.suse.com/support/security/rating/	external
https://ftp.suse.com/pub/projects/security/csaf/o…	self
https://bugzilla.suse.com/1253439	self
https://www.suse.com/security/cve/CVE-2025-40186/	self
https://www.suse.com/security/cve/CVE-2025-40186	external
https://bugzilla.suse.com/1253438	external
https://bugzilla.suse.com/1253439	external

JSON

To clipboard

{
  "document": {
    "aggregate_severity": {
      "namespace": "https://www.suse.com/support/security/rating/",
      "text": "important"
    },
    "category": "csaf_security_advisory",
    "csaf_version": "2.0",
    "distribution": {
      "text": "Copyright 2024 SUSE LLC. All rights reserved.",
      "tlp": {
        "label": "WHITE",
        "url": "https://www.first.org/tlp/"
      }
    },
    "lang": "en",
    "notes": [
      {
        "category": "summary",
        "text": "Security update for the Linux Kernel (Live Patch 1 for SUSE Linux Enterprise 16)",
        "title": "Title of the patch"
      },
      {
        "category": "description",
        "text": "\nThis update for the SUSE Linux Enterprise kernel 6.12.0-160000.6.1 fixes one security issue\n\nThe following security issue was fixed:\n\n- CVE-2025-40186: tcp: Don\u0027t call reqsk_fastopen_remove() in tcp_conn_request() (bsc#1253439).\n",
        "title": "Description of the patch"
      },
      {
        "category": "details",
        "text": "openSUSE-Leap-16.0-297",
        "title": "Patchnames"
      },
      {
        "category": "legal_disclaimer",
        "text": "CSAF 2.0 data is provided by SUSE under the Creative Commons License 4.0 with Attribution (CC-BY-4.0).",
        "title": "Terms of use"
      }
    ],
    "publisher": {
      "category": "vendor",
      "contact_details": "https://www.suse.com/support/security/contact/",
      "name": "SUSE Product Security Team",
      "namespace": "https://www.suse.com/"
    },
    "references": [
      {
        "category": "external",
        "summary": "SUSE ratings",
        "url": "https://www.suse.com/support/security/rating/"
      },
      {
        "category": "self",
        "summary": "URL of this CSAF notice",
        "url": "https://ftp.suse.com/pub/projects/security/csaf/opensuse-su-2026_20252-1.json"
      },
      {
        "category": "self",
        "summary": "SUSE Bug 1253439",
        "url": "https://bugzilla.suse.com/1253439"
      },
      {
        "category": "self",
        "summary": "SUSE CVE CVE-2025-40186 page",
        "url": "https://www.suse.com/security/cve/CVE-2025-40186/"
      }
    ],
    "title": "Security update for the Linux Kernel (Live Patch 1 for SUSE Linux Enterprise 16)",
    "tracking": {
      "current_release_date": "2026-02-18T16:14:15Z",
      "generator": {
        "date": "2026-02-18T16:14:15Z",
        "engine": {
          "name": "cve-database.git:bin/generate-csaf.pl",
          "version": "1"
        }
      },
      "id": "openSUSE-SU-2026:20252-1",
      "initial_release_date": "2026-02-18T16:14:15Z",
      "revision_history": [
        {
          "date": "2026-02-18T16:14:15Z",
          "number": "1",
          "summary": "Current version"
        }
      ],
      "status": "final",
      "version": "1"
    }
  },
  "product_tree": {
    "branches": [
      {
        "branches": [
          {
            "branches": [
              {
                "category": "product_version",
                "name": "kernel-livepatch-6_12_0-160000_6-default-4-160000.1.1.ppc64le",
                "product": {
                  "name": "kernel-livepatch-6_12_0-160000_6-default-4-160000.1.1.ppc64le",
                  "product_id": "kernel-livepatch-6_12_0-160000_6-default-4-160000.1.1.ppc64le"
                }
              }
            ],
            "category": "architecture",
            "name": "ppc64le"
          },
          {
            "branches": [
              {
                "category": "product_version",
                "name": "kernel-livepatch-6_12_0-160000_6-default-4-160000.1.1.s390x",
                "product": {
                  "name": "kernel-livepatch-6_12_0-160000_6-default-4-160000.1.1.s390x",
                  "product_id": "kernel-livepatch-6_12_0-160000_6-default-4-160000.1.1.s390x"
                }
              }
            ],
            "category": "architecture",
            "name": "s390x"
          },
          {
            "branches": [
              {
                "category": "product_version",
                "name": "kernel-livepatch-6_12_0-160000_6-default-4-160000.1.1.x86_64",
                "product": {
                  "name": "kernel-livepatch-6_12_0-160000_6-default-4-160000.1.1.x86_64",
                  "product_id": "kernel-livepatch-6_12_0-160000_6-default-4-160000.1.1.x86_64"
                }
              }
            ],
            "category": "architecture",
            "name": "x86_64"
          },
          {
            "branches": [
              {
                "category": "product_name",
                "name": "openSUSE Leap 16.0",
                "product": {
                  "name": "openSUSE Leap 16.0",
                  "product_id": "openSUSE Leap 16.0"
                }
              }
            ],
            "category": "product_family",
            "name": "SUSE Linux Enterprise"
          }
        ],
        "category": "vendor",
        "name": "SUSE"
      }
    ],
    "relationships": [
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "kernel-livepatch-6_12_0-160000_6-default-4-160000.1.1.ppc64le as component of openSUSE Leap 16.0",
          "product_id": "openSUSE Leap 16.0:kernel-livepatch-6_12_0-160000_6-default-4-160000.1.1.ppc64le"
        },
        "product_reference": "kernel-livepatch-6_12_0-160000_6-default-4-160000.1.1.ppc64le",
        "relates_to_product_reference": "openSUSE Leap 16.0"
      },
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "kernel-livepatch-6_12_0-160000_6-default-4-160000.1.1.s390x as component of openSUSE Leap 16.0",
          "product_id": "openSUSE Leap 16.0:kernel-livepatch-6_12_0-160000_6-default-4-160000.1.1.s390x"
        },
        "product_reference": "kernel-livepatch-6_12_0-160000_6-default-4-160000.1.1.s390x",
        "relates_to_product_reference": "openSUSE Leap 16.0"
      },
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "kernel-livepatch-6_12_0-160000_6-default-4-160000.1.1.x86_64 as component of openSUSE Leap 16.0",
          "product_id": "openSUSE Leap 16.0:kernel-livepatch-6_12_0-160000_6-default-4-160000.1.1.x86_64"
        },
        "product_reference": "kernel-livepatch-6_12_0-160000_6-default-4-160000.1.1.x86_64",
        "relates_to_product_reference": "openSUSE Leap 16.0"
      }
    ]
  },
  "vulnerabilities": [
    {
      "cve": "CVE-2025-40186",
      "ids": [
        {
          "system_name": "SUSE CVE Page",
          "text": "https://www.suse.com/security/cve/CVE-2025-40186"
        }
      ],
      "notes": [
        {
          "category": "general",
          "text": "In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: Don\u0027t call reqsk_fastopen_remove() in tcp_conn_request().\n\nsyzbot reported the splat below in tcp_conn_request(). [0]\n\nIf a listener is close()d while a TFO socket is being processed in\ntcp_conn_request(), inet_csk_reqsk_queue_add() does not set reqsk-\u003esk\nand calls inet_child_forget(), which calls tcp_disconnect() for the\nTFO socket.\n\nAfter the cited commit, tcp_disconnect() calls reqsk_fastopen_remove(),\nwhere reqsk_put() is called due to !reqsk-\u003esk.\n\nThen, reqsk_fastopen_remove() in tcp_conn_request() decrements the\nlast req-\u003ersk_refcnt and frees reqsk, and __reqsk_free() at the\ndrop_and_free label causes the refcount underflow for the listener\nand double-free of the reqsk.\n\nLet\u0027s remove reqsk_fastopen_remove() in tcp_conn_request().\n\nNote that other callers make sure tp-\u003efastopen_rsk is not NULL.\n\n[0]:\nrefcount_t: underflow; use-after-free.\nWARNING: CPU: 12 PID: 5563 at lib/refcount.c:28 refcount_warn_saturate (lib/refcount.c:28)\nModules linked in:\nCPU: 12 UID: 0 PID: 5563 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full)\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025\nRIP: 0010:refcount_warn_saturate (lib/refcount.c:28)\nCode: ab e8 8e b4 98 ff 0f 0b c3 cc cc cc cc cc 80 3d a4 e4 d6 01 00 75 9c c6 05 9b e4 d6 01 01 48 c7 c7 e8 df fb ab e8 6a b4 98 ff \u003c0f\u003e 0b e9 03 5b 76 00 cc 80 3d 7d e4 d6 01 00 0f 85 74 ff ff ff c6\nRSP: 0018:ffffa79fc0304a98 EFLAGS: 00010246\nRAX: d83af4db1c6b3900 RBX: ffff9f65c7a69020 RCX: d83af4db1c6b3900\nRDX: 0000000000000000 RSI: 00000000ffff7fff RDI: ffffffffac78a280\nRBP: 000000009d781b60 R08: 0000000000007fff R09: ffffffffac6ca280\nR10: 0000000000017ffd R11: 0000000000000004 R12: ffff9f65c7b4f100\nR13: ffff9f65c7d23c00 R14: ffff9f65c7d26000 R15: ffff9f65c7a64ef8\nFS:  00007f9f962176c0(0000) GS:ffff9f65fcf00000(0000) knlGS:0000000000000000\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 0000200000000180 CR3: 000000000dbbe006 CR4: 0000000000372ef0\nCall Trace:\n \u003cIRQ\u003e\n tcp_conn_request (./include/linux/refcount.h:400 ./include/linux/refcount.h:432 ./include/linux/refcount.h:450 ./include/net/sock.h:1965 ./include/net/request_sock.h:131 net/ipv4/tcp_input.c:7301)\n tcp_rcv_state_process (net/ipv4/tcp_input.c:6708)\n tcp_v6_do_rcv (net/ipv6/tcp_ipv6.c:1670)\n tcp_v6_rcv (net/ipv6/tcp_ipv6.c:1906)\n ip6_protocol_deliver_rcu (net/ipv6/ip6_input.c:438)\n ip6_input (net/ipv6/ip6_input.c:500)\n ipv6_rcv (net/ipv6/ip6_input.c:311)\n __netif_receive_skb (net/core/dev.c:6104)\n process_backlog (net/core/dev.c:6456)\n __napi_poll (net/core/dev.c:7506)\n net_rx_action (net/core/dev.c:7569 net/core/dev.c:7696)\n handle_softirqs (kernel/softirq.c:579)\n do_softirq (kernel/softirq.c:480)\n \u003c/IRQ\u003e",
          "title": "CVE description"
        }
      ],
      "product_status": {
        "recommended": [
          "openSUSE Leap 16.0:kernel-livepatch-6_12_0-160000_6-default-4-160000.1.1.ppc64le",
          "openSUSE Leap 16.0:kernel-livepatch-6_12_0-160000_6-default-4-160000.1.1.s390x",
          "openSUSE Leap 16.0:kernel-livepatch-6_12_0-160000_6-default-4-160000.1.1.x86_64"
        ]
      },
      "references": [
        {
          "category": "external",
          "summary": "CVE-2025-40186",
          "url": "https://www.suse.com/security/cve/CVE-2025-40186"
        },
        {
          "category": "external",
          "summary": "SUSE Bug 1253438 for CVE-2025-40186",
          "url": "https://bugzilla.suse.com/1253438"
        },
        {
          "category": "external",
          "summary": "SUSE Bug 1253439 for CVE-2025-40186",
          "url": "https://bugzilla.suse.com/1253439"
        }
      ],
      "remediations": [
        {
          "category": "vendor_fix",
          "details": "To install this SUSE Security Update use the SUSE recommended installation methods like YaST online_update or \"zypper patch\".\n",
          "product_ids": [
            "openSUSE Leap 16.0:kernel-livepatch-6_12_0-160000_6-default-4-160000.1.1.ppc64le",
            "openSUSE Leap 16.0:kernel-livepatch-6_12_0-160000_6-default-4-160000.1.1.s390x",
            "openSUSE Leap 16.0:kernel-livepatch-6_12_0-160000_6-default-4-160000.1.1.x86_64"
          ]
        }
      ],
      "scores": [
        {
          "cvss_v3": {
            "baseScore": 7,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "products": [
            "openSUSE Leap 16.0:kernel-livepatch-6_12_0-160000_6-default-4-160000.1.1.ppc64le",
            "openSUSE Leap 16.0:kernel-livepatch-6_12_0-160000_6-default-4-160000.1.1.s390x",
            "openSUSE Leap 16.0:kernel-livepatch-6_12_0-160000_6-default-4-160000.1.1.x86_64"
          ]
        }
      ],
      "threats": [
        {
          "category": "impact",
          "date": "2026-02-18T16:14:15Z",
          "details": "important"
        }
      ],
      "title": "CVE-2025-40186"
    }
  ]
}

CVE-2025-40186 (GCVE-0-2025-40186)

Vulnerability from cvelistv5 – Published: 2025-11-12 21:56 – Updated: 2026-08-05 12:08

Title

tcp: Don't call reqsk_fastopen_remove() in tcp_conn_request().

Summary

In the Linux kernel, the following vulnerability has been resolved: tcp: Don't call reqsk_fastopen_remove() in tcp_conn_request(). syzbot reported the splat below in tcp_conn_request(). [0] If a listener is close()d while a TFO socket is being processed in tcp_conn_request(), inet_csk_reqsk_queue_add() does not set reqsk->sk and calls inet_child_forget(), which calls tcp_disconnect() for the TFO socket. After the cited commit, tcp_disconnect() calls reqsk_fastopen_remove(), where reqsk_put() is called due to !reqsk->sk. Then, reqsk_fastopen_remove() in tcp_conn_request() decrements the last req->rsk_refcnt and frees reqsk, and __reqsk_free() at the drop_and_free label causes the refcount underflow for the listener and double-free of the reqsk. Let's remove reqsk_fastopen_remove() in tcp_conn_request(). Note that other callers make sure tp->fastopen_rsk is not NULL. [0]: refcount_t: underflow; use-after-free. WARNING: CPU: 12 PID: 5563 at lib/refcount.c:28 refcount_warn_saturate (lib/refcount.c:28) Modules linked in: CPU: 12 UID: 0 PID: 5563 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 RIP: 0010:refcount_warn_saturate (lib/refcount.c:28) Code: ab e8 8e b4 98 ff 0f 0b c3 cc cc cc cc cc 80 3d a4 e4 d6 01 00 75 9c c6 05 9b e4 d6 01 01 48 c7 c7 e8 df fb ab e8 6a b4 98 ff <0f> 0b e9 03 5b 76 00 cc 80 3d 7d e4 d6 01 00 0f 85 74 ff ff ff c6 RSP: 0018:ffffa79fc0304a98 EFLAGS: 00010246 RAX: d83af4db1c6b3900 RBX: ffff9f65c7a69020 RCX: d83af4db1c6b3900 RDX: 0000000000000000 RSI: 00000000ffff7fff RDI: ffffffffac78a280 RBP: 000000009d781b60 R08: 0000000000007fff R09: ffffffffac6ca280 R10: 0000000000017ffd R11: 0000000000000004 R12: ffff9f65c7b4f100 R13: ffff9f65c7d23c00 R14: ffff9f65c7d26000 R15: ffff9f65c7a64ef8 FS: 00007f9f962176c0(0000) GS:ffff9f65fcf00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000000180 CR3: 000000000dbbe006 CR4: 0000000000372ef0 Call Trace: <IRQ> tcp_conn_request (./include/linux/refcount.h:400 ./include/linux/refcount.h:432 ./include/linux/refcount.h:450 ./include/net/sock.h:1965 ./include/net/request_sock.h:131 net/ipv4/tcp_input.c:7301) tcp_rcv_state_process (net/ipv4/tcp_input.c:6708) tcp_v6_do_rcv (net/ipv6/tcp_ipv6.c:1670) tcp_v6_rcv (net/ipv6/tcp_ipv6.c:1906) ip6_protocol_deliver_rcu (net/ipv6/ip6_input.c:438) ip6_input (net/ipv6/ip6_input.c:500) ipv6_rcv (net/ipv6/ip6_input.c:311) __netif_receive_skb (net/core/dev.c:6104) process_backlog (net/core/dev.c:6456) __napi_poll (net/core/dev.c:7506) net_rx_action (net/core/dev.c:7569 net/core/dev.c:7696) handle_softirqs (kernel/softirq.c:579) do_softirq (kernel/softirq.c:480) </IRQ>

Severity

8.1 (High)


                        
                          CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Assigner

Linux mitre root Scorecard

References

8 references

URL	Tags
https://git.kernel.org/stable/c/e359b742eac1eac75…
https://git.kernel.org/stable/c/ff6a8883f96a5bc74…
https://git.kernel.org/stable/c/eb85ad5f23268d64b…
https://git.kernel.org/stable/c/643a94b0cf767325e…
https://git.kernel.org/stable/c/422c1c173c39bbbae…
https://git.kernel.org/stable/c/c11ace909e8731182…
https://git.kernel.org/stable/c/64dc47a13aa3d9daf…
https://git.kernel.org/stable/c/2e7cbbbe3d61c6360…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 7ec092a91ff351dcde89c23e795b73a328274db6 , < e359b742eac1eac75cff4e38ee2e8cea492acd9b (git) Affected: a4378dedd6e07e62f2fccb17d78c9665718763d0 , < ff6a8883f96a5bc74241ce5b3d431a6dcfa2124d (git) Affected: 33a4fdf0b4a25f8ce65380c3b0136b407ca57609 , < eb85ad5f23268d64b037bfb545cbcba3752f90c7 (git) Affected: 17d699727577814198d744d6afe54735c6b54c99 , < 643a94b0cf767325e953591c212be2eb826b9d7f (git) Affected: dfd06131107e7b699ef1e2a24ed2f7d17c917753 , < 422c1c173c39bbbae1e0eaaf8aefe40b2596233b (git) Affected: fa4749c065644af4db496b338452a69a3e5147d9 , < c11ace909e873118295e9eb22dc8c58b0b50eb32 (git) Affected: 45c8a6cc2bcd780e634a6ba8e46bffbdf1fc5c01 , < 64dc47a13aa3d9daf7cec29b44dca8e22a6aea15 (git) Affected: 45c8a6cc2bcd780e634a6ba8e46bffbdf1fc5c01 , < 2e7cbbbe3d61c63606994b7ff73c72537afe2e1c (git) Affected: ae313d14b45eca7a6bb29cb9bf396d977e7d28fb (git) Affected: 5.4.300 , < 5.4.301 (semver) Affected: 5.10.245 , < 5.10.246 (semver) Affected: 5.15.194 , < 5.15.195 (semver) Affected: 6.1.154 , < 6.1.157 (semver) Affected: 6.6.108 , < 6.6.113 (semver) Affected: 6.12.49 , < 6.12.54 (semver) Affected: 6.16.9 , < 6.17 (semver)
Linux	Linux	Affected: 6.17 Unaffected: 0 , < 6.17 (semver) Unaffected: 5.4.301 , ≤ 5.4.* (semver) Unaffected: 5.10.246 , ≤ 5.10.* (semver) Unaffected: 5.15.195 , ≤ 5.15.* (semver) Unaffected: 6.1.157 , ≤ 6.1.* (semver) Unaffected: 6.6.113 , ≤ 6.6.* (semver) Unaffected: 6.12.54 , ≤ 6.12.* (semver) Unaffected: 6.17.4 , ≤ 6.17.* (semver) Unaffected: 6.18 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/ipv4/tcp_input.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "e359b742eac1eac75cff4e38ee2e8cea492acd9b",
              "status": "affected",
              "version": "7ec092a91ff351dcde89c23e795b73a328274db6",
              "versionType": "git"
            },
            {
              "lessThan": "ff6a8883f96a5bc74241ce5b3d431a6dcfa2124d",
              "status": "affected",
              "version": "a4378dedd6e07e62f2fccb17d78c9665718763d0",
              "versionType": "git"
            },
            {
              "lessThan": "eb85ad5f23268d64b037bfb545cbcba3752f90c7",
              "status": "affected",
              "version": "33a4fdf0b4a25f8ce65380c3b0136b407ca57609",
              "versionType": "git"
            },
            {
              "lessThan": "643a94b0cf767325e953591c212be2eb826b9d7f",
              "status": "affected",
              "version": "17d699727577814198d744d6afe54735c6b54c99",
              "versionType": "git"
            },
            {
              "lessThan": "422c1c173c39bbbae1e0eaaf8aefe40b2596233b",
              "status": "affected",
              "version": "dfd06131107e7b699ef1e2a24ed2f7d17c917753",
              "versionType": "git"
            },
            {
              "lessThan": "c11ace909e873118295e9eb22dc8c58b0b50eb32",
              "status": "affected",
              "version": "fa4749c065644af4db496b338452a69a3e5147d9",
              "versionType": "git"
            },
            {
              "lessThan": "64dc47a13aa3d9daf7cec29b44dca8e22a6aea15",
              "status": "affected",
              "version": "45c8a6cc2bcd780e634a6ba8e46bffbdf1fc5c01",
              "versionType": "git"
            },
            {
              "lessThan": "2e7cbbbe3d61c63606994b7ff73c72537afe2e1c",
              "status": "affected",
              "version": "45c8a6cc2bcd780e634a6ba8e46bffbdf1fc5c01",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "ae313d14b45eca7a6bb29cb9bf396d977e7d28fb",
              "versionType": "git"
            },
            {
              "lessThan": "5.4.301",
              "status": "affected",
              "version": "5.4.300",
              "versionType": "semver"
            },
            {
              "lessThan": "5.10.246",
              "status": "affected",
              "version": "5.10.245",
              "versionType": "semver"
            },
            {
              "lessThan": "5.15.195",
              "status": "affected",
              "version": "5.15.194",
              "versionType": "semver"
            },
            {
              "lessThan": "6.1.157",
              "status": "affected",
              "version": "6.1.154",
              "versionType": "semver"
            },
            {
              "lessThan": "6.6.113",
              "status": "affected",
              "version": "6.6.108",
              "versionType": "semver"
            },
            {
              "lessThan": "6.12.54",
              "status": "affected",
              "version": "6.12.49",
              "versionType": "semver"
            },
            {
              "lessThan": "6.17",
              "status": "affected",
              "version": "6.16.9",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/ipv4/tcp_input.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.17"
            },
            {
              "lessThan": "6.17",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.4.*",
              "status": "unaffected",
              "version": "5.4.301",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.246",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.195",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.157",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.113",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.54",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.17.*",
              "status": "unaffected",
              "version": "6.17.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.18",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.4.301",
                  "versionStartIncluding": "5.4.300",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.246",
                  "versionStartIncluding": "5.10.245",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.195",
                  "versionStartIncluding": "5.15.194",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.157",
                  "versionStartIncluding": "6.1.154",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.113",
                  "versionStartIncluding": "6.6.108",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.54",
                  "versionStartIncluding": "6.12.49",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.17.4",
                  "versionStartIncluding": "6.17",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18",
                  "versionStartIncluding": "6.17",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "6.16.9",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: Don\u0027t call reqsk_fastopen_remove() in tcp_conn_request().\n\nsyzbot reported the splat below in tcp_conn_request(). [0]\n\nIf a listener is close()d while a TFO socket is being processed in\ntcp_conn_request(), inet_csk_reqsk_queue_add() does not set reqsk-\u003esk\nand calls inet_child_forget(), which calls tcp_disconnect() for the\nTFO socket.\n\nAfter the cited commit, tcp_disconnect() calls reqsk_fastopen_remove(),\nwhere reqsk_put() is called due to !reqsk-\u003esk.\n\nThen, reqsk_fastopen_remove() in tcp_conn_request() decrements the\nlast req-\u003ersk_refcnt and frees reqsk, and __reqsk_free() at the\ndrop_and_free label causes the refcount underflow for the listener\nand double-free of the reqsk.\n\nLet\u0027s remove reqsk_fastopen_remove() in tcp_conn_request().\n\nNote that other callers make sure tp-\u003efastopen_rsk is not NULL.\n\n[0]:\nrefcount_t: underflow; use-after-free.\nWARNING: CPU: 12 PID: 5563 at lib/refcount.c:28 refcount_warn_saturate (lib/refcount.c:28)\nModules linked in:\nCPU: 12 UID: 0 PID: 5563 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full)\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025\nRIP: 0010:refcount_warn_saturate (lib/refcount.c:28)\nCode: ab e8 8e b4 98 ff 0f 0b c3 cc cc cc cc cc 80 3d a4 e4 d6 01 00 75 9c c6 05 9b e4 d6 01 01 48 c7 c7 e8 df fb ab e8 6a b4 98 ff \u003c0f\u003e 0b e9 03 5b 76 00 cc 80 3d 7d e4 d6 01 00 0f 85 74 ff ff ff c6\nRSP: 0018:ffffa79fc0304a98 EFLAGS: 00010246\nRAX: d83af4db1c6b3900 RBX: ffff9f65c7a69020 RCX: d83af4db1c6b3900\nRDX: 0000000000000000 RSI: 00000000ffff7fff RDI: ffffffffac78a280\nRBP: 000000009d781b60 R08: 0000000000007fff R09: ffffffffac6ca280\nR10: 0000000000017ffd R11: 0000000000000004 R12: ffff9f65c7b4f100\nR13: ffff9f65c7d23c00 R14: ffff9f65c7d26000 R15: ffff9f65c7a64ef8\nFS:  00007f9f962176c0(0000) GS:ffff9f65fcf00000(0000) knlGS:0000000000000000\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 0000200000000180 CR3: 000000000dbbe006 CR4: 0000000000372ef0\nCall Trace:\n \u003cIRQ\u003e\n tcp_conn_request (./include/linux/refcount.h:400 ./include/linux/refcount.h:432 ./include/linux/refcount.h:450 ./include/net/sock.h:1965 ./include/net/request_sock.h:131 net/ipv4/tcp_input.c:7301)\n tcp_rcv_state_process (net/ipv4/tcp_input.c:6708)\n tcp_v6_do_rcv (net/ipv6/tcp_ipv6.c:1670)\n tcp_v6_rcv (net/ipv6/tcp_ipv6.c:1906)\n ip6_protocol_deliver_rcu (net/ipv6/ip6_input.c:438)\n ip6_input (net/ipv6/ip6_input.c:500)\n ipv6_rcv (net/ipv6/ip6_input.c:311)\n __netif_receive_skb (net/core/dev.c:6104)\n process_backlog (net/core/dev.c:6456)\n __napi_poll (net/core/dev.c:7506)\n net_rx_action (net/core/dev.c:7569 net/core/dev.c:7696)\n handle_softirqs (kernel/softirq.c:579)\n do_softirq (kernel/softirq.c:480)\n \u003c/IRQ\u003e"
        }
      ],
      "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 - The vulnerable code is in the TCP/IP stack\u0027s inbound SYN-processing path (tcp_v6_rcv \u2192 tcp_rcv_state_process \u2192 tcp_conn_request), triggered by a received TCP Fast Open SYN packet from a remote peer.\nAC:H - Triggering requires the listener socket to transition out of TCP_LISTEN (a local close()/shutdown()) at the exact moment an inbound TFO SYN is being processed; a remote attacker cannot control the timing of that close, so success depends on conditions beyond their control.\nPR:N - The TFO SYN is processed pre-connection with no authentication; an unauthenticated remote attacker needs no privileges to reach tcp_conn_request().\nUI:N - The bug is triggered purely by network packet processing racing with a listener close; no victim interaction is required.\nS:U - The corruption stays within the kernel\u0027s own memory/security authority (request_sock slab and listener refcount); no VM/IOMMU/sandbox boundary is crossed.\nC:H - The refcount underflow yields a use-after-free/double-free of a request_sock, giving an attacker control over freed-object contents that can be leveraged to read adjacent kernel memory.\nI:H - The double-free/UAF is a heap-corruption primitive that can be groomed into an arbitrary-write / control-flow-hijack, so integrity impact is high.\nA:H - The refcount underflow and double-free reliably corrupt kernel memory and crash the kernel (oops/panic in softirq context), a high availability impact."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:08:24.563Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/e359b742eac1eac75cff4e38ee2e8cea492acd9b"
        },
        {
          "url": "https://git.kernel.org/stable/c/ff6a8883f96a5bc74241ce5b3d431a6dcfa2124d"
        },
        {
          "url": "https://git.kernel.org/stable/c/eb85ad5f23268d64b037bfb545cbcba3752f90c7"
        },
        {
          "url": "https://git.kernel.org/stable/c/643a94b0cf767325e953591c212be2eb826b9d7f"
        },
        {
          "url": "https://git.kernel.org/stable/c/422c1c173c39bbbae1e0eaaf8aefe40b2596233b"
        },
        {
          "url": "https://git.kernel.org/stable/c/c11ace909e873118295e9eb22dc8c58b0b50eb32"
        },
        {
          "url": "https://git.kernel.org/stable/c/64dc47a13aa3d9daf7cec29b44dca8e22a6aea15"
        },
        {
          "url": "https://git.kernel.org/stable/c/2e7cbbbe3d61c63606994b7ff73c72537afe2e1c"
        }
      ],
      "title": "tcp: Don\u0027t call reqsk_fastopen_remove() in tcp_conn_request().",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-40186",
    "datePublished": "2025-11-12T21:56:29.033Z",
    "dateReserved": "2025-04-16T07:20:57.177Z",
    "dateUpdated": "2026-08-05T12:08:24.563Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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.

Action not permitted

OPENSUSE-SU-2026:20252-1

CVE-2025-40186 (GCVE-0-2025-40186)

Tags

Sightings

Nomenclature

Related by attack behaviour