NULL pointer dereference in Linux

CVE-2021-47223

In the Linux kernel, the following vulnerability has been resolved: net: bridge: fix vlan tunnel dst null pointer dereference This patch fixes a tunnel_dst null pointer dereference due to lockless access in the tunnel egress path. When deleting a vlan tunnel the tunnel_dst pointer is set to NULL without waiting a grace period (i.e. while it's still usable) and packets egressing are dereferencing it without checking. Use READ/WRITE_ONCE to annotate the lockless use of tunnel_id, use RCU for accessing tunnel_dst and make sure it is read only once and checked in the egress path. The dst is already properly RCU protected so we don't need to do anything fancy than to make sure tunnel_id and tunnel_dst are read only once and checked in the egress path.

Published · last modified .

CVSS v3 metric

CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.002 (13.2th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 13th percentile — 13.2% 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-2021-47223: held from 0.002 to 0.002.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000

Affected products

  • Linux — versions 11538d039ac6efcf4f1a6c536e1b87cd3668a9fd, 4.11, 0
  • Linux Kernel — versions 5.13

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2021-47223?
CVE-2021-47223 is a medium-severity vulnerability in Linux, classified under NULL Pointer Dereference. CVSS score: 5.5/10. Published 2024-05-21.
How severe is CVE-2021-47223?
Medium severity. CVSS v3 base score is 5.5 out of 10.