CVE-2020-28018

Exim 4 before 4.94.2 allows Use After Free in smtp_reset in certain situations that may be common for builds with OpenSSL.

Published: 2021-05-06 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2020-28018 is rated High Risk (68.7/100): CVSS Critical severity, with high exploitation likelihood (EPSS 65.91%, 99th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2020-28018

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-04-19 78.67% 65.91% -12.75%
2 2026-04-07 76.46% 78.67% +2.21%
3 2026-03-05 — 76.46% —

Full EPSS history (33 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2020-28018

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]
7.5 2.0 HIGH
AV:N/AC:L/Au:N/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 6.4 [email protected]

Weakness enumeration for CVE-2020-28018

OS Trackers for CVE-2020-28018

vendor priority summary link
alpine critical CVE-2020-28018: 1 source package rows (exim); 20 state rows across 7 repos (3.17-community, 3.18-community, 3.19-community, 3.20-community, 3.21-community, 3.22-community, edge-community); fixed 8, open 12. https://security.alpinelinux.org/vuln/CVE-2020-28018
debian unimportant CVE-2020-28018 unimportant priority: Debian including 1 source packages (exim4), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2020-28018
gentoo high CVE-2020-28018: 1 GLSA(s) (202105-01), 1 atom(s) (mail-mta/exim); latest impact high. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2020-28018
ubuntu medium CVE-2020-28018 medium priority: Ubuntu including 1 source packages (exim4), 9 status rows across 9 suites (bionic, focal, groovy, hirsute, impish, jammy, trusty, upstream, xenial): released 6, not-affected 2, needs-triage 1. https://ubuntu.com/security/CVE-2020-28018

Affected software / configurations for CVE-2020-28018

Vendor Product Version Raw CPE
exim exim >= 4.90, < 4.94.2 cpe:2.3:a:exim:exim:*:*:*:*:*:*:*:*

References for CVE-2020-28018

cvelogic Threat Intelligence