NVD / CVE Program· CNA mitre

CVE-2020-28896: Mutt before 2.0.2 and NeoMutt before 2020-11-20 did not ensure that $ssl_force_tls was processed if an IMAP server's initial server response

Noroxi assessment

Priority: Monitor (action score 22/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 2.3% (FIRST EPSS); higher than 83.5% of all records.
Anyone who can reach it over the internet can trigger it. No account or password is required. A user must open a link or visit a page. Special conditions such as timing or configuration are required.
Fixed version: mutt (AlmaLinux:8) 5:2.0.7-1.el8; mutt (Debian:12) 2.0.2-1; neomutt (Debian:12) 20201120+dfsg.1-1.

Low priority for now. Upgrade to mutt (AlmaLinux:8) 5:2.0.7-1.el8; mutt (Debian:12) 2.0.2-1; neomutt (Debian:12) 20201120+dfsg.1-1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

Mutt before 2.0.2 and NeoMutt before 2020-11-20 did not ensure that $ssl_force_tls was processed if an IMAP server's initial server response was invalid. The connection was not properly closed, and the code could continue attempting to authenticate. This could result in authentication credentials being exposed on an unencrypted connection, or to a machine-in-the-middle.

MediumCVSS 5.3 · v3.1—No exploit Fix available

Published: Nov 23, 2020
Updated: Jun 16, 2026
EPSS: 2.3% · 83th percentile
CWE: CWE-287

Report tools

JSON

Action score

Monitor

Low priority for now.

CVSS: 21 / 40 · 5.3 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 1 / 30 · 2.3%

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Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

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Noroxi analysis

What does it mean in your environment?

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
mutt	mutt	cpe:2.3:a:mutt:mutt
neomutt	neomutt	cpe:2.3:a:neomutt:neomutt
debian	debian linux	cpe:2.3:o:debian:debian_linux

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

debian debian linux9.0
mutt muttbefore 2.0.2
neomutt neomuttbefore 2020-11-20

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
AlmaLinux:8	mutt	before 5:2.0.7-1.el8	5:2.0.7-1.el8
Debian:12	mutt	before 2.0.2-1	2.0.2-1
Debian:12	neomutt	before 20201120+dfsg.1-1	20201120+dfsg.1-1
Debian:9	mutt	before 1.7.2-1+deb9u4	1.7.2-1+deb9u4
openSUSE:Leap 15.1	mutt	before 1.10.1-lp151.2.6.1	1.10.1-lp151.2.6.1
openSUSE:Leap 15.1	neomutt	before 20201120-lp152.2.3.1	20201120-lp152.2.3.1
openSUSE:Leap 15.2	mutt	before 1.10.1-lp152.3.6.1	1.10.1-lp152.3.6.1
openSUSE:Tumbleweed	mutt	before 2.0.7-2.2	2.0.7-2.2
openSUSE:Tumbleweed	neomutt	before 20210205-3.3	20210205-3.3
Red Hat:enterprise_linux:8::appstream	mutt	before 5:2.0.7-1.el8	5:2.0.7-1.el8
Red Hat:enterprise_linux:8::appstream	mutt-debuginfo	before 5:2.0.7-1.el8	5:2.0.7-1.el8
Red Hat:enterprise_linux:8::appstream	mutt-debugsource	before 5:2.0.7-1.el8	5:2.0.7-1.el8
Rocky Linux:8	mutt	before 5:2.0.7-1.el8	5:2.0.7-1.el8
SUSE:HPE Helion OpenStack 8	mutt	before 1.10.1-55.18.1	1.10.1-55.18.1
SUSE:Linux Enterprise Module for Basesystem 15 SP1	mutt	before 1.10.1-3.11.1	1.10.1-3.11.1
SUSE:Linux Enterprise Point of Sale 11 SP3	mutt	before 1.5.17-42.56.1	1.5.17-42.56.1
SUSE:Package Hub 15 SP1	neomutt	before 20201120-bp151.3.3.1	20201120-bp151.3.3.1
SUSE:Package Hub 15 SP2	neomutt	before 20201120-bp152.2.3.1	20201120-bp152.2.3.1

Same product

mutt: all records

Other highest-scoring records for the same primary product.

CVE-2018-14354An issue was discovered in Mutt before 1.10.1 and NeoMutt before 2018-07-16.
41Plan
CVE-2018-14362An issue was discovered in Mutt before 1.10.1 and NeoMutt before 2018-07-16.
40Plan
CVE-2018-14359An issue was discovered in Mutt before 1.10.1 and NeoMutt before 2018-07-16.
40Plan

Published before and after this one in the same product

← EarlierCVE-2020-14154Jun 15, 2020 · Mutt before 1.14.3 proceeds with a connection even if, in response to a GnuTLS certificate prompt, the user rejects an expired intermediate
19Monitor
← EarlierCVE-2020-14954Jun 21, 2020 · Mutt before 1.14.4 and NeoMutt before 2020-06-19 have a STARTTLS buffering issue that affects IMAP, SMTP, and POP3.
24Monitor
Later →CVE-2021-3181Jan 19, 2021 · rfc822.c in Mutt through 2.0.4 allows remote attackers to cause a denial of service (mailbox unavailability) by sending email messages with
27Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
almalinux:mutt	5:2.0.7-1.el8 · AlmaLinux:8	Package registry (OSV)
debian:mutt	2.0.2-1 · Debian:12	Package registry (OSV)
debian:neomutt	20201120+dfsg.1-1 · Debian:12	Package registry (OSV)
opensuse:mutt	1.10.1-lp151.2.6.1 · openSUSE:Leap 15.1	Package registry (OSV)
opensuse:neomutt	20201120-lp152.2.3.1 · openSUSE:Leap 15.1	Package registry (OSV)
red hat:mutt	5:2.0.7-1.el8 · Red Hat:enterprise_linux:8::appstream	Package registry (OSV)
red hat:mutt-debuginfo	5:2.0.7-1.el8 · Red Hat:enterprise_linux:8::appstream	Package registry (OSV)
red hat:mutt-debugsource	5:2.0.7-1.el8 · Red Hat:enterprise_linux:8::appstream	Package registry (OSV)
rocky linux:mutt	5:2.0.7-1.el8 · Rocky Linux:8	Package registry (OSV)
suse:mutt	1.5.17-42.56.1 · SUSE:Linux Enterprise Point of Sale 11 SP3	Package registry (OSV)
suse:neomutt	20201120-bp151.3.3.1 · SUSE:Package Hub 15 SP1	Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

Anyone who can reach it over the internet can trigger it.
No account or password is required.
A user must open a link or visit a page.
Special conditions such as timing or configuration are required.

If successful

Confidentiality: high · data can be read
Integrity: none
Availability: none

Attack vector: Network
Attack complexity: High
Privileges required: None
User interaction: Required
Scope: Unchanged
Confidentiality impact: High
Integrity impact: None
Availability impact: None

Weakness class (CWE)

CWE-287 · Improper Authentication

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N

nvd-primary

Root cause

Authentication is added route by route instead of being enforced in one place. When a route added later bypasses the shared middleware, the session check never runs for it.

The bug in code

The whole CWE-287 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1app.use("/admin", requireSession, adminRouter);
2

3// Route added later skips the middleware
4app.post("/admin-api/config", updateConfig);

Fixed

1const admin = express.Router();
2admin.use(requireSession, requireRole("admin"));
3

4admin.post("/config", updateConfig);
5app.use("/admin", admin);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Attack patterns (CAPEC)

ATT&CK techniques

Change log

Fix✗ → ✓Sep 28, 2026, 10:48 PM UTC

For records you follow, these changes also arrive as notifications. →

References

github.com/neomutt/neomutt/commit/9c36717a3e2af1f2c1b7242035455ec8112b4b06

Show all references (5 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records