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Fencer Vulns
high 7.5

CVE-2024-23185 json

Very large headers can cause resource exhaustion when parsing message.

published 2024-09-10 2 y ago modified 2026-06-17 4 mo ago also EUVD-2024-20704

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.3%
EPSS 1.3% chance of exploitation in 30 days, percentile 70%
public exploits
0
none known

Summary

Very large headers can cause resource exhaustion when parsing message. The message-parser normally reads reasonably sized chunks of the message. However, when it feeds them to message-header-parser, it starts building up "full_value" buffer out of the smaller chunks. The full_value buffer has no size limit, so large headers can cause large memory usage. It doesn't matter whether it's a single long header line, or a single header split into multiple lines. This bug exists in all Dovecot versions. Incoming mails typically have some size limits set by MTA, so even largest possible header size may still fit into Dovecot's vsz_limit. So attackers probably can't DoS a victim user this way. A user could APPEND larger mails though, allowing them to DoS themselves (although maybe cause some memory issues for the backend in general). One can implement restrictions on headers on MTA component preceding Dovecot. No publicly available exploits are known.

Patch / fix

  • dovecot dovecot 2.3.21.1
  • open-xchange dovecot 2.3.21.1
  • dovecot Debian 12 1:2.3.19.1+dfsg1-2.1+deb12u1
  • dovecot Debian 14, Debian 13 1:2.3.21.1+dfsg1-1

debian advisories DEBIAN-CVE-2024-23185

  • dovecot Ubuntu 20.04 LTS 1:2.3.7.2-1ubuntu3.7
  • dovecot Ubuntu 22.04 LTS 1:2.3.16+dfsg1-3ubuntu2.4
  • dovecot Ubuntu 24.04 LTS 1:2.3.21+dfsg1-2ubuntu6

ubuntu advisories UBUNTU-CVE-2024-23185

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • dovecot RHEL 8 1:2.3.16-6.el8_10
  • dovecot-mysql RHEL 8 1:2.3.16-6.el8_10
  • dovecot-pgsql RHEL 8 1:2.3.16-6.el8_10
  • dovecot-pigeonhole RHEL 8 1:2.3.16-6.el8_10
  • dovecot RHEL 9 1:2.3.16-11.el9_4.1
  • dovecot-mysql RHEL 9 1:2.3.16-11.el9_4.1
  • dovecot-pgsql RHEL 9 1:2.3.16-11.el9_4.1
  • dovecot-pigeonhole RHEL 9 1:2.3.16-11.el9_4.1

red hat advisories RHSA-2024:6973RHSA-2024:6529RHSA-2024:6465

  • dovecot23 SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +8 more 2.3.21.1-150200.76.1
  • dovecot23 SLES for SAP 15 SP4, SLES for SAP 15 SP3, SLES for SAP 15 SP2 +14 more 2.3.15-150200.65.1

suse advisories SUSE-SU-2026:4139-1SUSE-SU-2024:3118-1

  • dovecot24 openSUSE Tumbleweed 2.4.0-1.1
  • dovecot23 openSUSE Tumbleweed 2.3.21.1-1.1

opensuse advisories openSUSE-SU-2025:14715-1openSUSE-SU-2024:14274-1

  • dovecot AlmaLinux 8 1:2.3.16-6.el8_10
  • dovecot-mysql AlmaLinux 8 1:2.3.16-6.el8_10
  • dovecot-pgsql AlmaLinux 8 1:2.3.16-6.el8_10
  • dovecot-pigeonhole AlmaLinux 8 1:2.3.16-6.el8_10
  • dovecot AlmaLinux 9 1:2.3.16-11.el9_4.1
  • dovecot-mysql AlmaLinux 9 1:2.3.16-11.el9_4.1
  • dovecot-pgsql AlmaLinux 9 1:2.3.16-11.el9_4.1
  • dovecot-pigeonhole AlmaLinux 9 1:2.3.16-11.el9_4.1

almalinux advisories ALSA-2024:6973ALSA-2024:6529

  • dovecot Rocky Linux 8 1:2.3.16-6.el8_10
  • dovecot Rocky Linux 9 1:2.3.16-11.el9_4.1

rocky linux advisories RLSA-2024:6973RLSA-2024:6529

  • dovecot Alpine 3.24, Alpine 3.23, Alpine 3.22 +1 more 2.3.21.1-r0

alpine advisories ALPINE-CVE-2024-23185

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

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-2024-23185 updated cvss 6.8

dovecot: very large headers can cause resource exhaustion when parsing message

  • Red Hat Enterprise Linux 6 dovecot, dovecot-mysql, dovecot-pgsql, dovecot-pigeonhole Red Hat Enterprise Linux 7 dovecot, dovecot-mysql, dovecot-pgsql, dovecot-pigeonhole
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat CodeReady Linux Builder EUS (v.9.2) dovecot 2.3.16-8.el9_2.1
    fixed: vendor fix RHSA-2024:6465
  • Red Hat Enterprise Linux AppStream (v. 8) dovecot 2.3.16-6.el8_10, dovecot-mysql 2.3.16-6.el8_10, dovecot-pgsql 2.3.16-6.el8_10, dovecot-pigeonhole 2.3.16-6.el8_10
    fixed: vendor fix RHSA-2024:6973
  • Red Hat Enterprise Linux AppStream (v. 9) dovecot 2.3.16-11.el9_4.1, dovecot-mysql 2.3.16-11.el9_4.1, dovecot-pgsql 2.3.16-11.el9_4.1, dovecot-pigeonhole 2.3.16-11.el9_4.1
    fixed: vendor fix RHSA-2024:6529
  • Red Hat Enterprise Linux AppStream EUS (v.9.2) dovecot 2.3.16-8.el9_2.1, dovecot-mysql 2.3.16-8.el9_2.1, dovecot-pgsql 2.3.16-8.el9_2.1, dovecot-pigeonhole 2.3.16-8.el9_2.1
    fixed: vendor fix RHSA-2024:6465
  • Red Hat Enterprise Linux CRB (v. 8) dovecot 2.3.16-6.el8_10
    fixed: vendor fix RHSA-2024:6973
  • Red Hat Enterprise Linux CRB (v. 9) dovecot 2.3.16-11.el9_4.1
    fixed: vendor fix RHSA-2024:6529
  • Red Hat Enterprise Linux 10 dovecot
    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

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
2 y ago

Exploit prediction

1.29% chance of exploitation in the next 30 days, higher than 70% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Open-Xchange GmbH OX Dovecot Pro
  • open-xchange ox_dovecot_pro

Classification

Weakness
  • CWE-770 Allocation of Resources Without Limits or Throttling

References

Sources

Fencer Vulns 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.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.