5.5

CVE-2021-47223: linux NULL Pointer Dereference

CVSS: 5.5v3.1MediumAnalyzed
AliasesUBUNTU-CVE-2021-47223DEBIAN-CVE-2021-47223
Published 21-05-2024Last modified 11-05-2026
Open JSON

Vulnerability summary

CVE-2021-47223 is a medium (CVSS 5.5) NULL Pointer Dereference vulnerability in linux. EPSS estimates a 0.24% chance of exploitation in the next 30 days, higher than 13.7% of scored vulnerabilities.

Overall risk
22/100
0100
Low · default modelHow is this calculated?
CVSS score
5.5/10
010
Medium · v3.1 (NVD)
EPSS score
0.24%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 1 · Related 1
SUSE-SU-2025:0565-1

Timeline

  1. 21-05-2024
    PublishedVulnerability first disclosed.
  2. 11-05-2026
    Last modifiedVulnerability information updated.

Description

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.

CVSS metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.24%

Chance of exploitation in the next 30 days

Percentile

14%

Versus all other CVEs

30-day change

0.00 pp

From 0.24% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.24%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Ubuntu85 products
  • linux< 4.15.0-156.163 | < 5.4.0-81.91
  • linux-allwinner-5.19All versions (No fix recorded)
  • linux-aws< 4.15.0-1111.118 | < 5.4.0-1055.58
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11All versions (No fix recorded)
Linux2 products
  • linux≥ 11538d039ac6efcf4f1a6c536e1b87cd3668a9fd, < ad7feefe7164892db424c45687472db803d87f79 | ≥ 11538d039ac6efcf4f1a6c536e1b87cd3668a9fd, < 24a6e55f17aa123bc1fc54b7d3c410b41bc16530 | ≥ 11538d039ac6efcf4f1a6c536e1b87cd3668a9fd, < a2241e62f6b4a774d8a92048fdf59c45f6c2fe5c | ≥ 11538d039ac6efcf4f1a6c536e1b87cd3668a9fd, < fe0448a3fad365a747283a00a1d1ad5e8d6675b7 | ≥ 11538d039ac6efcf4f1a6c536e1b87cd3668a9fd, < abb02e05cb1c0a30dd873a29f33bc092067dc35d | ≥ 11538d039ac6efcf4f1a6c536e1b87cd3668a9fd, < 58e2071742e38f29f051b709a5cca014ba51166f | 4.11
  • linux_kernel≥ 4.11, < 4.14.238 | ≥ 4.15, < 4.19.196 | ≥ 4.20, < 5.4.128 | ≥ 5.5, < 5.10.46 | ≥ 5.11, < 5.12.13 | 5.13:rc1 | 5.13:rc2 | 5.13:rc3 | 5.13:rc4 | 5.13:rc5 | 5.13:rc6
Debian1 product
  • linux< 5.10.46-1

3 vendors · 88 products

References

10 links