CVE-2026-99139 (GCVE-0-2026-99139)

Vulnerability from cvelistv5 – Published: 2026-10-28 10:34 – Updated: 2026-10-28 10:34
VLAI
Title
tcp: fix use-after-free in do_tcp_getsockopt(TCP_CONGESTION)
Summary
In the Linux kernel, the following vulnerability has been resolved: tcp: fix use-after-free in do_tcp_getsockopt(TCP_CONGESTION) do_tcp_getsockopt() reads icsk->icsk_ca_ops->name without holding rcu_read_lock(). Since commit 0baf26b0fcd7 ("bpf: tcp: Support tcp_congestion_ops in bpf"), icsk_ca_ops can point to dynamically allocated BPF struct_ops memory that may be freed concurrently via setsockopt(TCP_CONGESTION), leading to a use-after-free. BUG: KASAN: slab-use-after-free in _copy_to_user+0x37/0x60 Read of size 16 at addr ffff888013505260 by task exploit/149 _copy_to_user+0x37/0x60 do_tcp_getsockopt+0x158a/0x2460 (net/ipv4/tcp.c:4585) tcp_getsockopt+0x91/0xf0 __sys_getsockopt+0xf7/0x170 Fix this by holding rcu_read_lock() around the ca_ops->name access, using READ_ONCE() to load icsk_ca_ops, and copying the name to a stack buffer before releasing the lock. Also annotate the relevant icsk_ca_ops stores with WRITE_ONCE() to fix the accompanying KCSAN data-race issue.
Severity
No CVSS data available.
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 7033 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 0baf26b0fcd74bbfcef53c5d5e8bad2b99c8d0d2 , < c1804ef016392dd91267d2207ee43b1de34302ca (git)
Affected: 0baf26b0fcd74bbfcef53c5d5e8bad2b99c8d0d2 , < a8e45471afa230c1431c26c8e99ec24377e3b514 (git)
Affected: 0baf26b0fcd74bbfcef53c5d5e8bad2b99c8d0d2 , < 5271b79b7ad68dcb222e893773f92bdabf7750f3 (git)
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Linux Linux Affected: 5.6
Unaffected: 0 , < 5.6 (semver)
Unaffected: 6.18.59 , ≤ 6.18.* (semver)
Unaffected: 7.2.13 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
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Show details on NVD website
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/ipv4/tcp.c",
            "net/ipv4/tcp_cong.c",
            "net/ipv4/tcp_dctcp.c",
            "net/ipv4/tcp_minisocks.c",
            "net/ipv4/tcp_output.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "c1804ef016392dd91267d2207ee43b1de34302ca",
              "status": "affected",
              "version": "0baf26b0fcd74bbfcef53c5d5e8bad2b99c8d0d2",
              "versionType": "git"
            },
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              "status": "affected",
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              "versionType": "git"
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        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/ipv4/tcp.c",
            "net/ipv4/tcp_cong.c",
            "net/ipv4/tcp_dctcp.c",
            "net/ipv4/tcp_minisocks.c",
            "net/ipv4/tcp_output.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.6"
            },
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              "versionType": "semver"
            },
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              "versionType": "semver"
            },
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              "status": "unaffected",
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              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
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              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.59",
                  "versionStartIncluding": "5.6",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.13",
                  "versionStartIncluding": "5.6",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "5.6",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: fix use-after-free in do_tcp_getsockopt(TCP_CONGESTION)\n\ndo_tcp_getsockopt() reads icsk-\u003eicsk_ca_ops-\u003ename without holding\nrcu_read_lock(). Since commit 0baf26b0fcd7 (\"bpf: tcp: Support\ntcp_congestion_ops in bpf\"), icsk_ca_ops can point to dynamically\nallocated BPF struct_ops memory that may be freed concurrently via\nsetsockopt(TCP_CONGESTION), leading to a use-after-free.\n\n  BUG: KASAN: slab-use-after-free in _copy_to_user+0x37/0x60\n  Read of size 16 at addr ffff888013505260 by task exploit/149\n   _copy_to_user+0x37/0x60\n   do_tcp_getsockopt+0x158a/0x2460 (net/ipv4/tcp.c:4585)\n   tcp_getsockopt+0x91/0xf0\n   __sys_getsockopt+0xf7/0x170\n\nFix this by holding rcu_read_lock() around the ca_ops-\u003ename access,\nusing READ_ONCE() to load icsk_ca_ops, and copying the name to a\nstack buffer before releasing the lock. Also annotate the relevant\nicsk_ca_ops stores with WRITE_ONCE() to fix the accompanying KCSAN\ndata-race issue."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-28T10:34:50.674Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
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          "url": "https://git.kernel.org/stable/c/c1804ef016392dd91267d2207ee43b1de34302ca"
        },
        {
          "url": "https://git.kernel.org/stable/c/a8e45471afa230c1431c26c8e99ec24377e3b514"
        },
        {
          "url": "https://git.kernel.org/stable/c/5271b79b7ad68dcb222e893773f92bdabf7750f3"
        }
      ],
      "title": "tcp: fix use-after-free in do_tcp_getsockopt(TCP_CONGESTION)",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-99139",
    "datePublished": "2026-10-28T10:34:50.674Z",
    "dateReserved": "2026-09-25T10:25:14.395Z",
    "dateUpdated": "2026-10-28T10:34:50.674Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-99139",
      "date": "2026-10-29",
      "epss": "0.00167",
      "percentile": "0.05899"
    },
    "microsoft_vex": {
      "current_release_date": "2026-10-29T01:05:21.000Z",
      "cve": "CVE-2026-99139",
      "id": "msrc_CVE-2026-99139",
      "initial_release_date": "2026-10-29T01:05:21.000Z",
      "product_status:known_affected": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "tcp: fix use-after-free in do_tcp_getsockopt(TCP_CONGESTION)",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-99139.json",
      "version": "1"
    },
    "nvd": {
      "cve": {
        "affected": [
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            "affectedData": [
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                "product": "Linux",
                "programFiles": [
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                  "net/ipv4/tcp_cong.c",
                  "net/ipv4/tcp_dctcp.c",
                  "net/ipv4/tcp_minisocks.c",
                  "net/ipv4/tcp_output.c"
                ],
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                    "versionType": "git"
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                ]
              },
              {
                "defaultStatus": "affected",
                "product": "Linux",
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                  "net/ipv4/tcp_minisocks.c",
                  "net/ipv4/tcp_output.c"
                ],
                "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                "vendor": "Linux",
                "versions": [
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                    "status": "unaffected",
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                    "versionType": "semver"
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                    "version": "6.18.59",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "7.2.*",
                    "status": "unaffected",
                    "version": "7.2.13",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "*",
                    "status": "unaffected",
                    "version": "7.3",
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                  }
                ]
              }
            ],
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          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: fix use-after-free in do_tcp_getsockopt(TCP_CONGESTION)\n\ndo_tcp_getsockopt() reads icsk-\u003eicsk_ca_ops-\u003ename without holding\nrcu_read_lock(). Since commit 0baf26b0fcd7 (\"bpf: tcp: Support\ntcp_congestion_ops in bpf\"), icsk_ca_ops can point to dynamically\nallocated BPF struct_ops memory that may be freed concurrently via\nsetsockopt(TCP_CONGESTION), leading to a use-after-free.\n\n  BUG: KASAN: slab-use-after-free in _copy_to_user+0x37/0x60\n  Read of size 16 at addr ffff888013505260 by task exploit/149\n   _copy_to_user+0x37/0x60\n   do_tcp_getsockopt+0x158a/0x2460 (net/ipv4/tcp.c:4585)\n   tcp_getsockopt+0x91/0xf0\n   __sys_getsockopt+0xf7/0x170\n\nFix this by holding rcu_read_lock() around the ca_ops-\u003ename access,\nusing READ_ONCE() to load icsk_ca_ops, and copying the name to a\nstack buffer before releasing the lock. Also annotate the relevant\nicsk_ca_ops stores with WRITE_ONCE() to fix the accompanying KCSAN\ndata-race issue."
          }
        ],
        "id": "CVE-2026-99139",
        "lastModified": "2026-10-28T11:17:33.850",
        "metrics": {},
        "published": "2026-10-28T11:17:33.850",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/5271b79b7ad68dcb222e893773f92bdabf7750f3"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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          },
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            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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          }
        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    }
  }
}



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