CVE-2023-3609 remediation guide
Linux Kernel, linux kernel, debian linux
A use-after-free vulnerability in the Linux kernel's net/sched: cls_u32 component can be exploited to achieve local privilege escalation. If tcf_change_indev() fails, u32_set_parms() will immediately return an error after incrementing or decrementing the reference counter in tcf_bind_filter(). If an attacker can control the reference counter and set it to zero, they can cause the reference to be freed, leading to a use-after-free vulnerability. We recommend upgrading past commit 04c55383fa5689357bcdd2c8036725a55ed632bc.
Identify the affected asset
Confirm whether Linux Kernel, linux kernel, debian linux is installed, record the deployed version and installation path, and identify exposed interfaces.
- Record the product name, package or appliance identifier, and installed version.
- Identify internet-facing, administrative, API, and internal access paths.
- Preserve the pre-change configuration and relevant service logs.
Validate the affected-version match
Compare the deployed version with the affected range: >= 4.14.0 < 4.14.322, >= 4.15.0 < 4.19.291, >= 4.20.0 < 5.4.248, >= 5.5.0 < 5.10.185, >= 5.11.0 < 5.15.118, >= 5.16.0 < 6.1.35, >= 6.2.0 < 6.3.9, >= 4.14 < 6.4, 6.4, 10.0, 11.0. Treat incomplete inventory results as unresolved.
Prioritize with independent signals
The CVSS severity warrants an early asset and exposure review. Combine this signal with asset criticality, exposure, compensating controls, and business impact.
Apply supported remediation
Follow the vendor advisory or supported update path. Current fixed-version status: 6.4. Preserve configuration and rollback material before change.
Verify the result
Confirm the resulting version, service health, authentication and access paths, monitoring coverage, and relevant security logs.
- Confirm the expected version and package state.
- Run a functional health check for critical service paths.
- Review authentication, error, application, and security monitoring logs.
- Reassess exposure if the supported fix cannot be applied.
Operational boundary
This page does not replace the vendor advisory, support contract, change-management process, or recovery plan. Do not infer that an asset is unaffected from an incomplete inventory query or a missing fixed-version field.