CVE-2024-36971

Linux, linux_kernel

Published 10 Jun 2024 · updated 17 Jun 2026 · Analyzed

7.8 High · CVSS 3.1, NVD

Exploited in the wild

CISA added this to its Known Exploited Vulnerabilities catalog on 7 Aug 2024, with a remediation deadline of 28 Aug 2024 for US federal agencies.

Required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

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.

References