Use After Free in Linux

CVE-2021-47259

In the Linux kernel, the following vulnerability has been resolved: NFS: Fix use-after-free in nfs4_init_client() KASAN reports a use-after-free when attempting to mount two different exports through two different NICs that belong to the same server. Olga was able to hit this with kernels starting somewhere between 5.7 and 5.10, but I traced the patch that introduced the clear_bit() call to 4.13. So something must have changed in the refcounting of the clp pointer to make this call to nfs_put_client() the very last one.

Vulnerability class: Use-After-Free

Published · last modified .

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.

EPSS exploit prediction

EPSS: 0.007 (52.1th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 52nd percentile — 52.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2021-47259: held from 0.007 to 0.007.

EPSS over last 30 days · oldest: 0.007 · newest: 0.007 · change: +0.000

Affected products

  • Linux — versions 8dcbec6d20eb881ba368d0aebc3a8a678aebb1da, 4.13, 0
  • Linux Kernel — versions 5.13

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2021-47259?
CVE-2021-47259 is a high-severity vulnerability in Linux, classified under Use After Free. CVSS score: 7.8/10. Published 2024-05-21.
How severe is CVE-2021-47259?
High severity. CVSS v3 base score is 7.8 out of 10.