What’s Vulnerable › Vulnerabilities

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

• Severity: medium (CVSS 5.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-06-25 · updated 2026-10-15

Description

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.

Affected products

• Linux kernel: from 2.6.12.1 before 6.1.176; from 6.2 before 6.6.143; from 6.7 before 6.12.94; from 6.13 before 6.18.36; from 6.19 before 7.0.13; 2.6.12, 2.6.12-rc2, 2.6.12-rc3, 2.6.12-rc4, 2.6.12-rc5, 7.1-rc1 (+6) — fixed in 6.1.176, 6.12.94, 6.18.36, 6.6.143, 7.0.13

How to fix

Upgrade to a fixed version: Linux kernel 6.1.176, 6.12.94, 6.18.36, 6.6.143. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/3747de241a66ef2c7032d2cc2b826a47c5fa0f6a
• https://git.kernel.org/stable/c/5d39580f68e6ddeedd15e587282207489dfb3da2
• https://git.kernel.org/stable/c/82b3e7ce10c53fc12aab8904745603efc74f8c07
• https://git.kernel.org/stable/c/c68517a3e18e20997808821c5559d0cba4d776c1
• https://git.kernel.org/stable/c/ecfe9171b26ae3eed0cd8bab7a943e9e2c9e51ba
• https://git.kernel.org/stable/c/ede69b8f6670600e534591664584f810d7c385f9
• https://cert-portal.siemens.com/productcert/html/ssa-019113.html
• https://cert-portal.siemens.com/productcert/html/ssa-457936.html
• https://cert-portal.siemens.com/productcert/html/ssa-784472.html

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