Use After Free in Linux

CVE-2024-36971

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.

Vulnerability class: Use-After-Free

EPSS: 0.027 (84.9th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

Affected products

Weakness classification (CWE)

CISA KEV (Known Exploited Vulnerabilities)

This CVE is on the CISA KEV catalog, added on . CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.

BOD 22-01 due date: .

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

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2024-36971?
CVE-2024-36971 is a high-severity vulnerability in Linux, classified under Use After Free. CVSS score: 7.8/10. Published 2024-06-10.
How severe is CVE-2024-36971?
High severity. CVSS v3 base score is 7.8 out of 10.
Is CVE-2024-36971 known to be exploited?
Yes. CVE-2024-36971 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2024-08-07), indicating it is being actively exploited. 6 public proof-of-concept repositories are indexed.