# CVE-2026-53236: tcp: restrict SO_ATTACH_FILTER to priv users

Status: published. Published: 2026-06-25. Updated: 2026-11-10.

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

tcp: restrict SO_ATTACH_FILTER to priv users

This patch restricts the use of SO_ATTACH_FILTER (cBPF) on TCP sockets
to users with CAP_NET_ADMIN capability.

This blocks potential side-channel attack where an unprivileged application
attaches a filter to leak TCP sequence/acknowledgment numbers.

## Remediation

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67) — https://git.kernel.org/stable/c/3747de241a66ef2c7032d2cc2b826a47c5fa0f6a
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67) — https://git.kernel.org/stable/c/5d39580f68e6ddeedd15e587282207489dfb3da2
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67) — https://git.kernel.org/stable/c/82b3e7ce10c53fc12aab8904745603efc74f8c07
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67) — https://git.kernel.org/stable/c/c68517a3e18e20997808821c5559d0cba4d776c1
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67) — https://git.kernel.org/stable/c/ecfe9171b26ae3eed0cd8bab7a943e9e2c9e51ba
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67) — https://git.kernel.org/stable/c/ede69b8f6670600e534591664584f810d7c385f9

## Affected products and versions

- Linux / Linux: ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2; < 3747de241a66ef2c7032d2cc2b826a47c5fa0f6a (affected, git); ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2; < ecfe9171b26ae3eed0cd8bab7a943e9e2c9e51ba (affected, git); ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2; < 82b3e7ce10c53fc12aab8904745603efc74f8c07 (affected, git); ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2; < ede69b8f6670600e534591664584f810d7c385f9 (affected, git); ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2; < c68517a3e18e20997808821c5559d0cba4d776c1 (affected, git); ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2; < 5d39580f68e6ddeedd15e587282207489dfb3da2 (affected, git). Source: CNA: Linux
- Linux / Linux: 2.6.12 (affected); ≥ 0; < 2.6.12 (unaffected, semver); ≥ 6.1.176; ≤ 6.1.* (unaffected, semver); ≥ 6.6.143; ≤ 6.6.* (unaffected, semver); ≥ 6.12.94; ≤ 6.12.* (unaffected, semver); ≥ 6.18.36; ≤ 6.18.* (unaffected, semver); ≥ 7.0.13; ≤ 7.0.* (unaffected, semver); ≥ 7.1; ≤ * (unaffected, original_commit_for_fix). Source: CNA: Linux
- Siemens / SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0): ≥ V3.1.6; < * (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0): ≥ V3.1.7; < * (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0): ≥ V3.1.6; < * (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0): ≥ V3.1.7; < * (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0): ≥ V3.1.6; < * (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0): ≥ V3.1.7; < * (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0): ≥ V3.1.6; < * (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0): ≥ V3.1.7; < * (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIMATIC S7-1500 TM MFP - GNU/Linux subsystem: ≥ 0; < * (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0): ≥ V3.1.6; < * (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0): ≥ V3.1.7; < * (affected, custom). Source: ADP: siemens-SADP

## NVD configuration conditions

Affected CPE matches depend on the following AND/OR and negation conditions:

```json
[
  {
    "negate": false,
    "nodes": [
      {
        "cpeMatch": [
          {
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionEndExcluding": "6.1.176",
            "versionStartIncluding": "2.6.12.1",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionEndExcluding": "6.6.143",
            "versionStartIncluding": "6.2",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionEndExcluding": "6.12.94",
            "versionStartIncluding": "6.7",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionEndExcluding": "6.18.36",
            "versionStartIncluding": "6.13",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionEndExcluding": "7.0.13",
            "versionStartIncluding": "6.19",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.12:-:*:*:*:*:*:*",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.12:rc2:*:*:*:*:*:*",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.12:rc3:*:*:*:*:*:*",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.12:rc4:*:*:*:*:*:*",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.12:rc5:*:*:*:*:*:*",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:*",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:*",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:linux:linux_kernel:7.1:rc3:*:*:*:*:*:*",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:linux:linux_kernel:7.1:rc4:*:*:*:*:*:*",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:linux:linux_kernel:7.1:rc5:*:*:*:*:*:*",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:linux:linux_kernel:7.1:rc6:*:*:*:*:*:*",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:linux:linux_kernel:7.1:rc7:*:*:*:*:*:*",
            "vulnerable": true
          }
        ],
        "negate": false,
        "operator": "OR"
      }
    ],
    "operator": "OR"
  }
]
```

## Severity and prioritization

- CVSS 3.1: 5.5 (medium); CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H; source: NVD: nvd@nist.gov

- CISA KEV: No listing in collected sources

- EPSS: 0.13% as of 2026-11-09; percentile 2.24%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: Not reported

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://git.kernel.org/stable/c/3747de241a66ef2c7032d2cc2b826a47c5fa0f6a (CNA: Linux)

- https://git.kernel.org/stable/c/ecfe9171b26ae3eed0cd8bab7a943e9e2c9e51ba (CNA: Linux)

- https://git.kernel.org/stable/c/82b3e7ce10c53fc12aab8904745603efc74f8c07 (CNA: Linux)

- https://git.kernel.org/stable/c/ede69b8f6670600e534591664584f810d7c385f9 (CNA: Linux)

- https://git.kernel.org/stable/c/c68517a3e18e20997808821c5559d0cba4d776c1 (CNA: Linux)

- https://git.kernel.org/stable/c/5d39580f68e6ddeedd15e587282207489dfb3da2 (CNA: Linux)

- https://cert-portal.siemens.com/productcert/html/ssa-019113.html (ADP: siemens-SADP)

- https://cert-portal.siemens.com/productcert/html/ssa-457936.html (ADP: siemens-SADP)

- https://cert-portal.siemens.com/productcert/html/ssa-784472.html (ADP: siemens-SADP)

- https://git.kernel.org/stable/c/3747de241a66ef2c7032d2cc2b826a47c5fa0f6a (416baaa9-dc9f-4396-8d5f-8c081fb06d67; Patch)

- https://git.kernel.org/stable/c/5d39580f68e6ddeedd15e587282207489dfb3da2 (416baaa9-dc9f-4396-8d5f-8c081fb06d67; Patch)

- https://git.kernel.org/stable/c/82b3e7ce10c53fc12aab8904745603efc74f8c07 (416baaa9-dc9f-4396-8d5f-8c081fb06d67; Patch)

- https://git.kernel.org/stable/c/c68517a3e18e20997808821c5559d0cba4d776c1 (416baaa9-dc9f-4396-8d5f-8c081fb06d67; Patch)

- https://git.kernel.org/stable/c/ecfe9171b26ae3eed0cd8bab7a943e9e2c9e51ba (416baaa9-dc9f-4396-8d5f-8c081fb06d67; Patch)

- https://git.kernel.org/stable/c/ede69b8f6670600e534591664584f810d7c385f9 (416baaa9-dc9f-4396-8d5f-8c081fb06d67; Patch)

- https://cert-portal.siemens.com/productcert/html/ssa-019113.html (0b142b55-0307-4c5a-b3c9-f314f3fb7c5e)

- https://cert-portal.siemens.com/productcert/html/ssa-457936.html (0b142b55-0307-4c5a-b3c9-f314f3fb7c5e)

- https://cert-portal.siemens.com/productcert/html/ssa-784472.html (0b142b55-0307-4c5a-b3c9-f314f3fb7c5e)

## Provenance

- CNA: Linux: https://www.cve.org/CVERecord?id=CVE-2026-53236; retrieved 2026-11-10; source updated 2026-11-10

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-53236; retrieved 2026-11-06; source updated 2026-11-06

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-53236; retrieved 2026-11-10; source updated Not reported

Revision: 56b1cf5bbf14680a718d251d6501581db66fc3d4b83fb2272e2bc807e81e8d11

Canonical: https://y2.dev/cve/CVE-2026-53236

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