Vulnerability-Lookup

GHSA-83J6-PC2M-JHG5

Vulnerability from github – Published: 2026-09-03 15:32 – Updated: 2026-09-04 06:31

Details

In the Linux kernel, the following vulnerability has been resolved:

bpf: Check sk_state before sk_protocol in bpf_tcp_*_syncookie

bpf_tcp_gen_syncookie and bpf_tcp_check_syncookie accept a socket pointer 'sk' with argument type ARG_PTR_TO_BTF_ID_SOCK_COMMON. However, they access sk->sk_protocol without validating whether 'sk' represents a full socket.

Fix this issue by checking sk->sk_state != TCP_LISTEN before inspecting sk->sk_protocol in both bpf_tcp_gen_syncookie and bpf_tcp_check_syncookie. Since mini-sockets are never in the TCP_LISTEN state, the condition short-circuits and prevents dereferencing fullsock-specific fields.

Severity

7.3 (High)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-80738"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-03T13:06:12Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Check sk_state before sk_protocol in bpf_tcp_*_syncookie\n\nbpf_tcp_gen_syncookie and bpf_tcp_check_syncookie accept a socket pointer\n\u0027sk\u0027 with argument type ARG_PTR_TO_BTF_ID_SOCK_COMMON. However, they access\nsk-\u003esk_protocol without validating whether \u0027sk\u0027 represents a full socket.\n\nFix this issue by checking sk-\u003esk_state != TCP_LISTEN before inspecting\nsk-\u003esk_protocol in both bpf_tcp_gen_syncookie and bpf_tcp_check_syncookie.\nSince mini-sockets are never in the TCP_LISTEN state, the condition\nshort-circuits and prevents dereferencing fullsock-specific fields.",
  "id": "GHSA-83j6-pc2m-jhg5",
  "modified": "2026-09-04T06:31:20Z",
  "published": "2026-09-03T15:32:15Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-80738"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/23f682083aa3fbc0c49667818efd6979a8bc5ac2"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/31a420a822ff92e2090bd5d65efe8e34e2d6d9b8"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-80738 (GCVE-0-2026-80738)

Vulnerability from cvelistv5 – Published: 2026-09-03 08:21 – Updated: 2026-09-04 04:58

Title

bpf: Check sk_state before sk_protocol in bpf_tcp_*_syncookie

Summary

In the Linux kernel, the following vulnerability has been resolved: bpf: Check sk_state before sk_protocol in bpf_tcp_*_syncookie bpf_tcp_gen_syncookie and bpf_tcp_check_syncookie accept a socket pointer 'sk' with argument type ARG_PTR_TO_BTF_ID_SOCK_COMMON. However, they access sk->sk_protocol without validating whether 'sk' represents a full socket. Fix this issue by checking sk->sk_state != TCP_LISTEN before inspecting sk->sk_protocol in both bpf_tcp_gen_syncookie and bpf_tcp_check_syncookie. Since mini-sockets are never in the TCP_LISTEN state, the condition short-circuits and prevents dereferencing fullsock-specific fields.

Severity

7.3 (High)


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

Assigner

Linux mitre root

References

2 references

URL	Tags
https://git.kernel.org/stable/c/23f682083aa3fbc0c…
https://git.kernel.org/stable/c/31a420a822ff92e20…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 399040847084a69f345e0a52fd62f04654e0fce3 , < 23f682083aa3fbc0c49667818efd6979a8bc5ac2 (git) Affected: 399040847084a69f345e0a52fd62f04654e0fce3 , < 31a420a822ff92e2090bd5d65efe8e34e2d6d9b8 (git)
Linux	Linux	Affected: 5.2 Unaffected: 0 , < 5.2 (semver) Unaffected: 7.1.9 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/core/filter.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "23f682083aa3fbc0c49667818efd6979a8bc5ac2",
              "status": "affected",
              "version": "399040847084a69f345e0a52fd62f04654e0fce3",
              "versionType": "git"
            },
            {
              "lessThan": "31a420a822ff92e2090bd5d65efe8e34e2d6d9b8",
              "status": "affected",
              "version": "399040847084a69f345e0a52fd62f04654e0fce3",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/core/filter.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.2"
            },
            {
              "lessThan": "5.2",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.9",
                  "versionStartIncluding": "5.2",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "5.2",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Check sk_state before sk_protocol in bpf_tcp_*_syncookie\n\nbpf_tcp_gen_syncookie and bpf_tcp_check_syncookie accept a socket pointer\n\u0027sk\u0027 with argument type ARG_PTR_TO_BTF_ID_SOCK_COMMON. However, they access\nsk-\u003esk_protocol without validating whether \u0027sk\u0027 represents a full socket.\n\nFix this issue by checking sk-\u003esk_state != TCP_LISTEN before inspecting\nsk-\u003esk_protocol in both bpf_tcp_gen_syncookie and bpf_tcp_check_syncookie.\nSince mini-sockets are never in the TCP_LISTEN state, the condition\nshort-circuits and prevents dereferencing fullsock-specific fields."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.3,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The flaw is in bpf_tcp_gen_syncookie/bpf_tcp_check_syncookie BPF helpers invoked only from locally loaded and attached TC clsact or XDP programs via bpf(); per kernel CNA guidance BPF/tc paths are Local even when later triggered by ingress packets.\nAC:L - An attacker who loads the BPF program fully controls passing bpf_skc_lookup_tcp() results (request_sock/TCP_NEW_SYN_RECV or timewait sockets) into the syncookie helpers and can reliably trigger the bad sk_protocol read with crafted SYN/ACK traffic; no uncontrollable races or rare layout are required.\nPR:L - Exploitation requires bpf(BPF_PROG_LOAD) (CAP_BPF, obtainable in user namespaces) plus attaching TC/XDP hooks (CAP_NET_ADMIN via unshare -Urn); no init-namespace root is needed, matching CNA guidance for namespace-reachable net/BPF capabilities.\nUI:N - No victim mount, login, or cooperative action is required; once the attacker loads and attaches their BPF program, sending network packets from their own processes deterministically reaches the vulnerable helper on each matching lookup.\nS:U - Impact is confined to kernel heap disclosure/type confusion within the host kernel security domain; it does not cross VM, container runtime, IOMMU, or other security-authority boundaries.\nC:H - Casting a mini-socket to struct sock and reading sk_protocol performs a fixed-offset out-of-bounds read (~300+ bytes past request_sock/inet_timewait_sock) into adjacent slab memory, leaking kernel heap contents including pointers usable for further local exploitation.\nI:H - This is type confusion between ARG_PTR_TO_BTF_ID_SOCK_COMMON mini-sockets and full struct sock fields; per CNA guidance type confusion is rated High integrity impact even though the immediate bug is a read, because mis-typed socket pointers corrupt the kernel\u0027s object model.\nA:L - The primary impact is information disclosure; while the out-of-bounds u16 read usually stays within the slab page, reads near allocation boundaries or under KASAN can fault and oops the kernel, giving at least Low availability impact when uncertain."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-04T04:58:23.870Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/23f682083aa3fbc0c49667818efd6979a8bc5ac2"
        },
        {
          "url": "https://git.kernel.org/stable/c/31a420a822ff92e2090bd5d65efe8e34e2d6d9b8"
        }
      ],
      "title": "bpf: Check sk_state before sk_protocol in bpf_tcp_*_syncookie",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-80738",
    "datePublished": "2026-09-03T08:21:53.143Z",
    "dateReserved": "2026-08-26T14:34:25.789Z",
    "dateUpdated": "2026-09-04T04:58:23.870Z",
    "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.

Detection rules are retrieved from Rulezet.

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.
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GHSA-83J6-PC2M-JHG5

CVE-2026-80738 (GCVE-0-2026-80738)

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