Skip to content
Noroxi
NVD / CVE Program· CNA OX

CVE-2024-23185: Very large headers can cause resource exhaustion when parsing message.

Noroxi assessment

Priority: Monitor (action score 30/100)

  • 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: 1.2% (FIRST EPSS); higher than 70.5% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: dovecot (AlmaLinux:8) 1:2.3.16-6.el8_10; dovecot-devel (AlmaLinux:8) 1:2.3.16-6.el8_10; dovecot-mysql (AlmaLinux:8) 1:2.3.16-6.el8_10.

Low priority for now. Upgrade to dovecot (AlmaLinux:8) 1:2.3.16-6.el8_10; dovecot-devel (AlmaLinux:8) 1:2.3.16-6.el8_10; dovecot-mysql (AlmaLinux:8) 1:2.3.16-6.el8_10 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

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.

HighCVSS 7.5 · v3.1—No exploit Fix available
Published
Sep 10, 2024
Updated
Jun 17, 2026
EPSS
1.2% · 70th percentile

Report tools

JSON

Action score

30

Monitor

Low priority for now.

CVSS
30 / 40 · 7.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 1.2%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · OX
7.5
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

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

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2024-23185

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

One daily email digest (06:00 UTC); connect a webhook for KEV listings and weaponized exploits instantly.

Your free account also gets you

Running WordPress? Scan your site free with WP Lens

  • Stack alerts: add the products and versions you run, get the new CVEs that affect them
  • Uptime monitoring: 1 site, instant email when it goes down
  • Add your domain: subdomains and takeover risk scanned every week (1 domain)
  • 10 scans an hour on the security tools (3 a day without an account), an API key and MCP
  • All your scans in one panel: findings, what changed in the last scan, a report per domain or per client (PDF, share link)
All free tools

Sign up with email · Have an account? Sign in

Free account, no card. Unfollow any time.

Don't want an account? Get "Exploited this week" by email every MondayDon't want an account? RSS feed for open-xchange gmbh records

Running WordPress? Scan your site free with WP Lens

Is your version affected? Check it

Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

We use this product, ask for help

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.

VendorProduct
open-xchangeox dovecot pro

Versions reported by the vendor

Affected version ranges reported by the assigning authority (OX). Independent of NVD's CPE analysis and usually ahead of it.

  • Open-Xchange GmbH OX Dovecot Pro

    • up to and including 2.3.21affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
AlmaLinux:8dovecotbefore 1:2.3.16-6.el8_101:2.3.16-6.el8_10
AlmaLinux:8dovecot-develbefore 1:2.3.16-6.el8_101:2.3.16-6.el8_10
AlmaLinux:8dovecot-mysqlbefore 1:2.3.16-6.el8_101:2.3.16-6.el8_10
AlmaLinux:8dovecot-pgsqlbefore 1:2.3.16-6.el8_101:2.3.16-6.el8_10
AlmaLinux:8dovecot-pigeonholebefore 1:2.3.16-6.el8_101:2.3.16-6.el8_10
AlmaLinux:9dovecotbefore 1:2.3.16-11.el9_4.11:2.3.16-11.el9_4.1
AlmaLinux:9dovecot-develbefore 1:2.3.16-11.el9_4.11:2.3.16-11.el9_4.1
AlmaLinux:9dovecot-mysqlbefore 1:2.3.16-11.el9_4.11:2.3.16-11.el9_4.1
AlmaLinux:9dovecot-pgsqlbefore 1:2.3.16-11.el9_4.11:2.3.16-11.el9_4.1
AlmaLinux:9dovecot-pigeonholebefore 1:2.3.16-11.el9_4.11:2.3.16-11.el9_4.1
Alpine:v3.21dovecotbefore 2.3.21.1-r02.3.21.1-r0
Debian:11dovecotbefore 1:2.3.13+dfsg1-2+deb11u21:2.3.13+dfsg1-2+deb11u2
Debian:12dovecotbefore 1:2.3.19.1+dfsg1-2.1+deb12u11:2.3.19.1+dfsg1-2.1+deb12u1
Debian:13dovecotbefore 1:2.3.21.1+dfsg1-11:2.3.21.1+dfsg1-1
openSUSE:Leap 15.5dovecot23before 2.3.15-150200.65.12.3.15-150200.65.1
openSUSE:Tumbleweeddovecot23before 2.3.21.1-1.12.3.21.1-1.1
Red Hat:enterprise_linux:8::appstreamdovecotbefore 1:2.3.16-6.el8_101:2.3.16-6.el8_10
Red Hat:enterprise_linux:8::appstreamdovecot-debuginfobefore 1:2.3.16-6.el8_101:2.3.16-6.el8_10
Red Hat:enterprise_linux:8::appstreamdovecot-debugsourcebefore 1:2.3.16-6.el8_101:2.3.16-6.el8_10
Red Hat:enterprise_linux:8::appstreamdovecot-mysqlbefore 1:2.3.16-6.el8_101:2.3.16-6.el8_10
Red Hat:enterprise_linux:8::appstreamdovecot-mysql-debuginfobefore 1:2.3.16-6.el8_101:2.3.16-6.el8_10
Red Hat:enterprise_linux:8::appstreamdovecot-pgsqlbefore 1:2.3.16-6.el8_101:2.3.16-6.el8_10
Red Hat:enterprise_linux:8::appstreamdovecot-pgsql-debuginfobefore 1:2.3.16-6.el8_101:2.3.16-6.el8_10
Red Hat:enterprise_linux:8::appstreamdovecot-pigeonholebefore 1:2.3.16-6.el8_101:2.3.16-6.el8_10

+26

Same product

open-xchange gmbh: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-42007An attacker that has valid credentials can use a Sieve script with the editheader extension to trigger a use-after-free in the mail editing
    36Monitor
  • CVE-2026-42391An unauthenticated attacker can send an IMAP ID command with a very large number of parameters before logging in, which causes memory and CP
    30Monitor
  • CVE-2026-33605An unauthenticated attacker can crash the ManageSieve login process by sending a small malformed command before authenticating.
    30Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2024-25584Sep 6, 2024 · Dovecot accepts dot LF DOT LF symbol as end of DATA command.
    21Monitor
  • ← EarlierCVE-2024-23184Sep 10, 2024 · Having a large number of address headers (From, To, Cc, Bcc, etc.) becomes excessively CPU intensive.
    20Monitor
  • Later →CVE-2025-30189Oct 31, 2025 · When cache is enabled, some passdb/userdb drivers incorrectly cache all users with same cache key, causing wrong cached information to be us
    29Monitor

Remediation

Which version to upgrade to

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

Product / packageFixed versionSource
almalinux:dovecot1:2.3.16-11.el9_4.1 · AlmaLinux:9Package registry (OSV)
almalinux:dovecot-devel1:2.3.16-11.el9_4.1 · AlmaLinux:9Package registry (OSV)
almalinux:dovecot-mysql1:2.3.16-11.el9_4.1 · AlmaLinux:9Package registry (OSV)
almalinux:dovecot-pgsql1:2.3.16-11.el9_4.1 · AlmaLinux:9Package registry (OSV)
almalinux:dovecot-pigeonhole1:2.3.16-11.el9_4.1 · AlmaLinux:9Package registry (OSV)
alpine:dovecot2.3.21.1-r0 · Alpine:v3.21Package registry (OSV)
debian:dovecot1:2.3.19.1+dfsg1-2.1+deb12u1 · Debian:12Package registry (OSV)
opensuse:dovecot232.3.15-150200.65.1 · openSUSE:Leap 15.5Package registry (OSV)
red hat:dovecot1:2.3.16-8.el9_2.1 · Red Hat:rhel_eus:9.2::appstreamPackage registry (OSV)
red hat:dovecot-debuginfo1:2.3.16-8.el9_2.1 · Red Hat:rhel_eus:9.2::appstreamPackage registry (OSV)
red hat:dovecot-debugsource1:2.3.16-8.el9_2.1 · Red Hat:rhel_eus:9.2::appstreamPackage registry (OSV)
red hat:dovecot-devel1:2.3.16-8.el9_2.1 · Red Hat:rhel_eus:9.2::crbPackage registry (OSV)
red hat:dovecot-mysql1:2.3.16-8.el9_2.1 · Red Hat:rhel_eus:9.2::appstreamPackage registry (OSV)
red hat:dovecot-mysql-debuginfo1:2.3.16-8.el9_2.1 · Red Hat:rhel_eus:9.2::appstreamPackage registry (OSV)
red hat:dovecot-pgsql1:2.3.16-8.el9_2.1 · Red Hat:rhel_eus:9.2::appstreamPackage registry (OSV)
red hat:dovecot-pgsql-debuginfo1:2.3.16-8.el9_2.1 · Red Hat:rhel_eus:9.2::appstreamPackage registry (OSV)
red hat:dovecot-pigeonhole1:2.3.16-8.el9_2.1 · Red Hat:rhel_eus:9.2::appstreamPackage registry (OSV)
red hat:dovecot-pigeonhole-debuginfo1:2.3.16-8.el9_2.1 · Red Hat:rhel_eus:9.2::appstreamPackage registry (OSV)
rocky linux:dovecot1:2.3.16-11.el9_4.1 · Rocky Linux:9Package registry (OSV)
suse:dovecot232.3.15-150200.65.1 · SUSE:Linux Enterprise Module for Server Applications 15 SP5Package 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.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

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

No commit or PR link among the references.

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.

  • CVE-2024-231840 days apartHaving a large number of address headers (From, To, Cc, Bcc, etc.) becomes excessively CPU intensive.
    20Monitor

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.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-770 · Allocation of Resources Without Limits or Throttling

CVSS vector

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

nvd-secondary

Attack context

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

Change log

  1. Fix✗ → ✓

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

References

Show all references (3 more)

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

All records