What is CVE-2021-23909?

CVE-2021-23909 is a medium-severity vulnerability in Mercedes-Benz A 220, classified under Out-of-bounds Write. CVSS score: 6.3/10. Published 2021-05-13.

How severe is CVE-2021-23909?

Medium severity. CVSS v3 base score is 6.3 out of 10.

Buffer overflow in Mercedes-Benz A 220

CVE-2021-23909

An issue was discovered in HERMES 2.1 in the MBUX Infotainment System on Mercedes-Benz vehicles through 2021. The SH2 MCU allows remote code execution.

Vulnerability class: Buffer Overflow

Published 2021-05-13 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.3 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:H/A:H.

EPSS exploit prediction

EPSS: 0.024 (83.1th percentile), scored 2026-09-30.

Low probability of exploitation in the next 30 days, but still tracked. 83rd percentile — 83.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.024 · newest: 0.024 · change: 0.000

Affected products

Weakness classification (CWE)

CWE-787 — Out-of-bounds Write

References

media.daimler.com/marsMediaSite/en/instance/ko.xhtml (Third Party Advisory)
keenlab.tencent.com/en/2021/05/12/Tencent-Security-Keen-Lab-Experimental-Securi… (Third Party Advisory)
keenlab.tencent.com/en/whitepapers/Mercedes_Benz_Security_Research_Report_Final… (Exploit, Third Party Advisory)

Frequently asked questions

What is CVE-2021-23909?: CVE-2021-23909 is a medium-severity vulnerability in Mercedes-Benz A 220, classified under Out-of-bounds Write. CVSS score: 6.3/10. Published 2021-05-13.
How severe is CVE-2021-23909?: Medium severity. CVSS v3 base score is 6.3 out of 10.