Local privilege escalation via cls_fw use-after-free
Published Jul 21, 2023 · Updated Mar 5, 2025
Use-after-free in Linux kernel cls_fw before 6.5 allows local users to gain elevated privileges through traffic-control configuration. In fw_set_parms(), a tcf_change_indev() failure returns after tcf_bind_filter() changes the reference count, allowing a controlled zero count to free a still-referenced object. Local low-privileged access and control of the classifier reference-count path are required; successful exploitation grants elevated kernel privileges.
Summary
What happened
Use-after-free in Linux kernel cls_fw before 6.5 allows local users to gain elevated privileges through traffic-control configuration. In fw_set_parms(), a tcf_change_indev() failure returns after tcf_bind_filter() changes the reference count, allowing a controlled zero count to free a still-referenced object. Local low-privileged access and control of the classifier reference-count path are required; successful exploitation grants elevated kernel privileges.
The record
- CVE
- CVE-2023-3776
- Published
- Jul 21, 2023
- Updated
- Mar 5, 2025
- Vendor
- The Linux Kernel Organization
- Product
- Linux Kernel
- Classifications
- CWE-416, T1068
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Jul 21, 2023CVE publishedPublication date reported by the CVE source.
- Mar 5, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=2.6 <6.5
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Public exploit references
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Technologies
Your stack
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Your stack
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