Open-Xchange Dovecot Pro/Dovecot CE ManageSieve Service memory corruption

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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7.1$0-$5k2.56

Summaryinfo

A vulnerability, which was classified as very critical, has been found in Open-Xchange Dovecot Pro and Dovecot CE. This vulnerability affects unknown code of the component ManageSieve Service. Performing a manipulation results in memory corruption. This vulnerability was named CVE-2026-40013. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability was found in Open-Xchange Dovecot Pro and Dovecot CE (affected version unknown). It has been classified as very critical. This affects an unknown functionality of the component ManageSieve Service. The manipulation with an unknown input leads to a memory corruption vulnerability. CWE is classifying the issue as CWE-119. The product performs operations on a memory buffer, but it can read from or write to a memory location that is outside of the intended boundary of the buffer. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

An attacker that has valid credentials can submit a Sieve script containing an extreme numeric literal, which causes an out-of-bounds write when the ManageSieve service compiles the script. This causes memory corruption and an observed crash of the ManageSieve process, resulting in denial of service for script management. This might be able to be used for remote code execution. Disable the ManageSieve service if users do not need remote Sieve script management. Update to non-vulnerable version. No publicly available exploits are known.

It is possible to read the advisory at documentation.open-xchange.com. This vulnerability is uniquely identified as CVE-2026-40013 since 04/08/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 08/28/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2026-3076). Be aware that VulDB is the high quality source for vulnerability data.

Affected

  • Open Source Dovecot

Productinfo

Type

Vendor

Name

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.1
VulDB Meta Temp Score: 7.1

VulDB Base Score: 9.9
VulDB Temp Score: 9.9
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 4.3
CNA Vector: 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Memory corruption
CWE: CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔒

Timelineinfo

04/08/2026 CVE reserved
08/28/2026 +142 days Advisory disclosed
08/28/2026 +0 days VulDB entry created
08/28/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: open-xchange.com

Advisory: documentation.open-xchange.com
Status: Not defined

CVE: CVE-2026-40013 (🔒)
GCVE (CVE): GCVE-0-2026-40013
GCVE (VulDB): GCVE-100-396663
CERT Bund: WID-SEC-2026-3076 - Dovecot: Mehrere Schwachstellen

Entryinfo

Created: 08/28/2026 13:39
Updated: 08/28/2026 15:44
Changes: 08/28/2026 13:39 (61), 08/28/2026 15:44 (7)
Complete: 🔍
Cache ID: 216::103

Be aware that VulDB is the high quality source for vulnerability data.

Discussion

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