CVE-2020-14954Network attack vector

Protocol response injection via retained STARTTLS data

Published Jun 21, 2020 · Updated Aug 4, 2024

Response injection in Mutt before 1.14.4 and NeoMutt before 2020-06-19 allows man-in-the-middle attackers to forge mail-protocol responses. After a STARTTLS acknowledgment, connection readers retain bytes following the line terminator and later process them as authenticated TLS-session responses. The attacker must intercept an IMAP, POP3, or SMTP connection during STARTTLS negotiation; injected replies can falsify protocol state or mimic a mailbox session.

CVSS severity5.9
Medium
EPSS probability2.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Response injection in Mutt before 1.14.4 and NeoMutt before 2020-06-19 allows man-in-the-middle attackers to forge mail-protocol responses. After a STARTTLS acknowledgment, connection readers retain bytes following the line terminator and later process them as authenticated TLS-session responses. The attacker must intercept an IMAP, POP3, or SMTP connection during STARTTLS negotiation; injected replies can falsify protocol state or mimic a mailbox session.

The record

CVE
CVE-2020-14954
Published
Jun 21, 2020
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-74, T1557
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 21, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.9NIST NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:P/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
T1557Adversary-in-the-Middle

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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