CVE-2020-7957Network attack vector

Mailbox denial of service via snippet-generation crash

Published Feb 12, 2020 · Updated Aug 4, 2024

Improper input validation in Dovecot Core 2.3.9 allows remote attackers to make a recipient's mailbox unreadable via crafted email. Snippet generation crashes when a large message spans multiple parser body blocks, the initial blocks lack a complete snippet, and the input ends with “>”. The crafted message must reach IMAP or LMTP snippet processing, after which mail can remain stuck in delivery or the recipient can lose access to all messages.

CVSS severity5.3
Medium
EPSS probability1.88%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in Dovecot Core 2.3.9 allows remote attackers to make a recipient's mailbox unreadable via crafted email. Snippet generation crashes when a large message spans multiple parser body blocks, the initial blocks lack a complete snippet, and the input ends with “>”. The crafted message must reach IMAP or LMTP snippet processing, after which mail can remain stuck in delivery or the recipient can lose access to all messages.

The record

CVE
CVE-2020-7957
Published
Feb 12, 2020
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-20, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 12, 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

5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
3.1Open-XchangeCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L
3.1MITRECVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L
5.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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-20Improper Input Validation
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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