What is CVE-2020-28023?

CVE-2020-28023 is a high-severity vulnerability in Exim, classified under Out-of-bounds Read. CVSS score: 7.5/10. Published 2021-05-06.

How severe is CVE-2020-28023?

High severity. CVSS v3 base score is 7.5 out of 10.

Is CVE-2020-28023 known to be exploited?

5 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Out-of-bounds Read in Exim

CVE-2020-28023

Exim 4 before 4.94.2 allows Out-of-bounds Read. smtp_setup_msg may disclose sensitive information from process memory to an unauthenticated SMTP client.

Vulnerability class: Buffer Overflow

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

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.

EPSS exploit prediction

EPSS: 0.026 (84.8th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 85th percentile — 84.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.026 · newest: 0.026 · change: 0.000

Affected products

Exim

Weakness classification (CWE)

CWE-125 — Out-of-bounds Read

Public proof-of-concept exploits

References

www.exim.org/static/doc/security/CVE-2020-qualys/CVE-2020-28023-SCHAD.txt (Third Party Advisory)

Frequently asked questions

What is CVE-2020-28023?: CVE-2020-28023 is a high-severity vulnerability in Exim, classified under Out-of-bounds Read. CVSS score: 7.5/10. Published 2021-05-06.
How severe is CVE-2020-28023?: High severity. CVSS v3 base score is 7.5 out of 10.
Is CVE-2020-28023 known to be exploited?: 5 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.