CVE-2024-27397: netfilter: nf_tables: use timestamp to check for set element timeout

Vulnerability summary

CVE-2024-27397 is a high (CVSS 7.8) Use After Free vulnerability in linux. EPSS estimates a 0.26% chance of exploitation in the next 30 days, higher than 18.4% of scored vulnerabilities.

Timeline

1. 09-05-2024
   PublishedVulnerability first disclosed.
2. 15-10-2026
   Last modifiedVulnerability information updated.

Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: use timestamp to check for set element timeout Add a timestamp field at the beginning of the transaction, store it in the nftables per-netns area. Update set backend .insert, .deactivate and sync gc path to use the timestamp, this avoids that an element expires while control plane transaction is still unfinished. .lookup and .update, which are used from packet path, still use the current time to check if the element has expired. And .get path and dump also since this runs lockless under rcu read size lock. Then, there is async gc which also needs to check the current time since it runs asynchronously from a workqueue.

• 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 Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.