CVE & CISA-KEV Catalog

CVE-2026-40016

MEDIUM
5.3
CVSS v3
NVD

Description

Attacker can upload a malicious Sieve script over ManageSieve service (or locally) to bypass configured CPU time limits for Sieve up to 130 times of the configured limit. Attacker can use this to degrade server performance and bypass configured CPU time limits for Sieve scripts. Install fixed version, or alternatively prevent direct access to Sieve scripts via ManageSieve or local access. No publicly available exploits are known.

How to fix

Remediation Available
dovecotDebian
Fixed in:1:2.3.19.1+dfsg1-2.1+deb12u6CVE-2026-40016
Fixed in:1:2.4.1+dfsg1-6+deb13u6CVE-2026-40016
Fixed in:1:2.4.4+dfsg1-1CVE-2026-40016
dovecotUbuntu
Fixed in:1:2.3.16+dfsg1-3ubuntu2.9USN-8365-1
Fixed in:1:2.3.21+dfsg1-2ubuntu6.5USN-8365-1
Fixed in:1:2.4.1+dfsg1-5ubuntu4.2USN-8365-1
dovecot-coreUbuntu
Fixed in:1:2.3.16+dfsg1-3ubuntu2.9USN-8365-1
Fixed in:1:2.3.21+dfsg1-2ubuntu6.5USN-8365-1
Fixed in:1:2.4.1+dfsg1-5ubuntu4.2USN-8365-1

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork
Attack ComplexityHigh
Privileges RequiredLow
User InteractionNone
ScopeUnchanged

Impact

ConfidentialityNone
IntegrityNone
AvailabilityHigh

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

Exploit Intelligence

0.34%probability of exploitation in 30 days
26thpercentile

Low risk: more likely to be exploited than 26% of all known CVEs.

References

Related Vulnerabilities

Other CWE-400 (Resource Exhaustion) vulnerabilities, ordered by exploit likelihood. View all

CVESeverityCVSSEPSSExploitedFix
CVE-2023-44487High7.5100%KEVFix
CVE-2021-44228Critical10.0100%KEV + RansomFix
CVE-2011-3192High7.899%-Fix
CVE-2019-11478Medium5.395%-Fix
CVE-2024-25617Medium5.389%-Fix
CVE-2018-1000115High7.589%-Fix
Embed a live status badge for CVE-2026-40016
CVE-2026-40016 severity badge

Markdown

[![CVE-2026-40016](https://tridentstack.com/cve/badge/CVE-2026-40016.svg)](https://tridentstack.com/cve/CVE-2026-40016)

HTML

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-05-18.