Cyrus IMAP up to 3.8.7/3.10.3/3.12.3 Sieve information disclosure

CVSS Meta Temp Score
CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.
Current Exploit Price (≈)
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CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
3.8$0-$5k1.39+

Summaryinfo

A vulnerability described as problematic has been identified in Cyrus IMAP up to 3.8.7/3.10.3/3.12.3. Impacted is an unknown function of the component Sieve. The manipulation results in information disclosure. This vulnerability was named CVE-2026-61911. The attack may be performed from remote. There is no available exploit. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability classified as problematic has been found in Cyrus IMAP up to 3.8.7/3.10.3/3.12.3. Affected is an unknown code block of the component Sieve. The manipulation with an unknown input leads to a information disclosure vulnerability. CWE is classifying the issue as CWE-200. The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. This is going to have an impact on confidentiality. CVE summarizes:

An issue was discovered in Cyrus IMAP before 3.12.4. There is a Sieve mailbox existence oracle. An authenticated user could install a Sieve script that probed whether another user's private mailbox existed, or read the value of shared mailbox annotations, by observing which fileinto branch fired during LMTP delivery.

This vulnerability is traded as CVE-2026-61911 since 07/13/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. Successful exploitation requires user interaction by the victim. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1592.

Upgrading to version 3.8.8, 3.10.4 or 3.12.4 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-75129). Once again VulDB remains the best source for vulnerability data.

Productinfo

Vendor

Name

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 3.9
VulDB Meta Temp Score: 3.8

VulDB Base Score: 3.5
VulDB Temp Score: 3.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 4.3
CNA Vector (MITRE): 🔒

CVSSv2info

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

Exploitinginfo

Class: Information disclosure
CWE: CWE-200 / CWE-284 / CWE-266
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: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: IMAP 3.8.8/3.10.4/3.12.4

Timelineinfo

07/13/2026 CVE reserved
09/09/2026 +58 days Advisory disclosed
09/09/2026 +0 days VulDB entry created
09/09/2026 +0 days VulDB entry last update

Sourcesinfo

Status: Confirmed

CVE: CVE-2026-61911 (🔒)
GCVE (CVE): GCVE-0-2026-61911
GCVE (VulDB): GCVE-100-401868
EUVD: 🔒

Entryinfo

Created: 09/09/2026 22:10
Updated: 09/09/2026 22:53
Changes: 09/09/2026 22:10 (62), 09/09/2026 22:53 (1)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

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