CVE-2024-36971: Android Kernel Remote Code Execution Vulnerability

Vulnerability summary

CVE-2024-36971 is a high (CVSS 7.8) Use After Free vulnerability in Android Kernel. It is known to be exploited: CISA lists it, first on 07-08-2024. EPSS estimates a 2.70% chance of exploitation in the next 30 days, higher than 85.9% of scored vulnerabilities.

Timeline

1. 10-06-2024
   PublishedVulnerability first disclosed.
2. 07-08-2024
   Added to CISA KEVExploitedAndroid Kernel Remote Code Execution Vulnerability
3. 28-08-2024
   CISA remediation dueDeadline passedApply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
4. 05-08-2026
   Last modifiedVulnerability information updated.

Description

In the Linux kernel, the following vulnerability has been resolved: net: fix __dst_negative_advice() race __dst_negative_advice() does not enforce proper RCU rules when sk->dst_cache must be cleared, leading to possible UAF. RCU rules are that we must first clear sk->sk_dst_cache, then call dst_release(old_dst). Note that sk_dst_reset(sk) is implementing this protocol correctly, while __dst_negative_advice() uses the wrong order. Given that ip6_negative_advice() has special logic against RTF_CACHE, this means each of the three ->negative_advice() existing methods must perform the sk_dst_reset() themselves. Note the check against NULL dst is centralized in __dst_negative_advice(), there is no need to duplicate it in various callbacks. Many thanks to Clement Lecigne for tracking this issue. This old bug became visible after the blamed commit, using UDP sockets.

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 Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.