What is CVE-2018-21027?

CVE-2018-21027 is a critical-severity vulnerability in Boa, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. CVSS score: 9.8/10. Published 2019-10-11.

How severe is CVE-2018-21027?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Buffer overflow in Boa

CVE-2018-21027

Boa through 0.94.14rc21 allows remote attackers to trigger an out-of-memory (OOM) condition because malloc is mishandled.

Vulnerability class: Buffer Overflow

Published 2019-10-11 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.024 (83.2th percentile), scored 2026-09-30.

Low probability of exploitation in the next 30 days, but still tracked. 83rd percentile — 83.2% 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-119 — Improper Restriction of Operations within the Bounds of a Memory Buffer

References

github.com/gpg/boa/pull/1 (Third Party Advisory)
github.com/gpg/boa/pull/1/commits/e139b87835994d007fbd64eead6c1455d7b8cf4e (Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2018-21027?: CVE-2018-21027 is a critical-severity vulnerability in Boa, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. CVSS score: 9.8/10. Published 2019-10-11.
How severe is CVE-2018-21027?: Critical severity. CVSS v3 base score is 9.8 out of 10.