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Fencer Intel
low 3.1

CVE-2020-7957 json

The IMAP and LMTP components in Dovecot 2.3.9 before 2.3.9.3 mishandle snippet generation when many characters must be read to compute the…

published 6y ago modified 4mo ago also EUVD-2020-28877

cvss
3.1
version 3.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.9%
EPSS 1.9% chance of exploitation in 30 days, percentile 79%
public exploits
0
none known

Summary

The IMAP and LMTP components in Dovecot 2.3.9 before 2.3.9.3 mishandle snippet generation when many characters must be read to compute the snippet and a trailing > character exists. This causes a denial of service in which the recipient cannot read all of their messages.

Patch / fix

  • dovecot dovecot 2.3.9.3
  • dovecot24 openSUSE Tumbleweed 2.4.0-1.1
  • dovecot23 openSUSE Tumbleweed 2.3.16-1.6

opensuse advisories openSUSE-SU-2025:14715-1openSUSE-SU-2024:10726-1

  • dovecot Alpine 3.10, Alpine 3.9, Alpine 3.8 2.3.10.1-r0
  • dovecot Alpine 3.24, Alpine 3.23, Alpine 3.22 +11 more 2.3.9.3-r0

alpine advisories ALPINE-CVE-2020-7957

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • dovecot Arch Linux 2.3.9.3-1

arch linux advisories AVG-1097

Is CVE-2020-7957 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2020-7957 updated cvss 5.3

dovecot: specially crafted email can cause mailbox to have permanently unaccessible mail

  • Red Hat Enterprise Linux 5 dovecot Red Hat Enterprise Linux 6 dovecot, dovecot-mysql, dovecot-pgsql, dovecot-pigeonhole Red Hat Enterprise Linux 7 dovecot, dovecot-mysql, dovecot-pgsql, dovecot-pigeonhole Red Hat Enterprise Linux 8 dovecot, dovecot-mysql, dovecot-pgsql, dovecot-pigeonhole
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

1.88% chance of exploitation in the next 30 days, higher than 79% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • openwall.com http://www.openwall.com/lists/oss-security/2020/02/12/2 referenced PoC, tagged "exploit" by a source, unverified
  • dovecot.org https://dovecot.org/pipermail/dovecot-news/2020-February/000430.html referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.0 3.1 CVSS:3.0/AC:H/AV:N/A:L/C:N/I:N/PR:N/S:U/UI:R
NVD 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
CNA 3.0 3.1 CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P

Classification

Weakness
  • CWE-20 Improper Input Validation

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.