CVE-2026-43198 (GCVE-0-2026-43198)

Vulnerability from cvelistv5 – Published: 2026-05-06 11:28 – Updated: 2026-05-08 12:41
VLAI?
Title
tcp: fix potential race in tcp_v6_syn_recv_sock()
Summary
In the Linux kernel, the following vulnerability has been resolved: tcp: fix potential race in tcp_v6_syn_recv_sock() Code in tcp_v6_syn_recv_sock() after the call to tcp_v4_syn_recv_sock() is done too late. After tcp_v4_syn_recv_sock(), the child socket is already visible from TCP ehash table and other cpus might use it. Since newinet->pinet6 is still pointing to the listener ipv6_pinfo bad things can happen as syzbot found. Move the problematic code in tcp_v6_mapped_child_init() and call this new helper from tcp_v4_syn_recv_sock() before the ehash insertion. This allows the removal of one tcp_sync_mss(), since tcp_v4_syn_recv_sock() will call it with the correct context.
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
Linux Linux Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < fe89b2f05b854847784f91127319172945c1fadd (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 7178e2a8027423b2af17ab95df73a749a5b72e5b (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 858d2a4f67ff69e645a43487ef7ea7f28f06deae (git)
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    Linux Linux Affected: 2.6.12
Unaffected: 0 , < 2.6.12 (semver)
Unaffected: 6.18.16 , ≤ 6.18.* (semver)
Unaffected: 6.19.6 , ≤ 6.19.* (semver)
Unaffected: 7.0 , ≤ * (original_commit_for_fix)
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{
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      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "include/net/inet_connection_sock.h",
            "include/net/tcp.h",
            "net/ipv4/syncookies.c",
            "net/ipv4/tcp_fastopen.c",
            "net/ipv4/tcp_ipv4.c",
            "net/ipv4/tcp_minisocks.c",
            "net/ipv6/tcp_ipv6.c",
            "net/mptcp/subflow.c",
            "net/smc/af_smc.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
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            "net/ipv4/syncookies.c",
            "net/ipv4/tcp_fastopen.c",
            "net/ipv4/tcp_ipv4.c",
            "net/ipv4/tcp_minisocks.c",
            "net/ipv6/tcp_ipv6.c",
            "net/mptcp/subflow.c",
            "net/smc/af_smc.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "version": "2.6.12"
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            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
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      "cpeApplicability": [
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      "descriptions": [
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: fix potential race in tcp_v6_syn_recv_sock()\n\nCode in tcp_v6_syn_recv_sock() after the call to tcp_v4_syn_recv_sock()\nis done too late.\n\nAfter tcp_v4_syn_recv_sock(), the child socket is already visible\nfrom TCP ehash table and other cpus might use it.\n\nSince newinet-\u003epinet6 is still pointing to the listener ipv6_pinfo\nbad things can happen as syzbot found.\n\nMove the problematic code in tcp_v6_mapped_child_init()\nand call this new helper from tcp_v4_syn_recv_sock() before\nthe ehash insertion.\n\nThis allows the removal of one tcp_sync_mss(), since\ntcp_v4_syn_recv_sock() will call it with the correct\ncontext."
        }
      ],
      "metrics": [
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          "cvssV3_1": {
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            "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"
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        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/fe89b2f05b854847784f91127319172945c1fadd"
        },
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        },
        {
          "url": "https://git.kernel.org/stable/c/858d2a4f67ff69e645a43487ef7ea7f28f06deae"
        }
      ],
      "title": "tcp: fix potential race in tcp_v6_syn_recv_sock()",
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        "engine": "bippy-1.2.0"
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    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-43198",
    "datePublished": "2026-05-06T11:28:05.569Z",
    "dateReserved": "2026-05-01T14:12:55.992Z",
    "dateUpdated": "2026-05-08T12:41:10.445Z",
    "state": "PUBLISHED"
  },
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  "vulnerability-lookup:meta": {
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      "date": "2026-05-09",
      "epss": "0.0004",
      "percentile": "0.12251"
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  }
}


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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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