CVE-2023-3776: Use-after-free in Linux kernel's net/sched: cls_fw component

Vulnerability summary

CVE-2023-3776 is a high (CVSS 7.8) Use After Free vulnerability in debian debian_linux. EPSS estimates a 0.51% chance of exploitation in the next 30 days, higher than 43.4% of scored vulnerabilities.

Timeline

1. 21-07-2023
   PublishedVulnerability first disclosed.
2. 05-03-2025
   Last modifiedVulnerability information updated.

Description

A use-after-free vulnerability in the Linux kernel's net/sched: cls_fw component can be exploited to achieve local privilege escalation. If tcf_change_indev() fails, fw_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 0323bce598eea038714f941ce2b22541c46d488f.

• CWE-416Use After FreeThe product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.