CVE-2026-27858
7.5 · HIGHAttacker can send a specifically crafted message before authentication that causes managesieve to allocate large amount of memory.
Overview
CVE-2026-27858 is a high-severity vulnerability. It was published on March 27, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).
This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical description
Attacker can send a specifically crafted message before authentication that causes managesieve to allocate large amount of memory.
Attacker can force managesieve-login to be unavailable by repeatedly crashing the process. Protect access to managesieve protocol, or install fixed version. No publicly available exploits are known.
Remediation
Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
References
How CyberStrike helps
Reason, not just scan
It reasons through your app's logic the way a human pentester would, so it finds flaws signature scanners miss.
Learn moreVerified findings
Every finding is proven exploitable before you see it, which cuts the false positives that bury real risk.
Learn moreAI-driven DAST and SAST
Probe running apps and read source from one engine, so issues are caught before and after they ship.
Learn moreOpen source
Read exactly how it tests and what it reports. CyberStrike is open source and in early access.
View the repo
Frequently asked questions
What is CVE-2026-27858?
CVE-2026-27858 is a high-severity vulnerability. It was published on March 27, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).
How severe is CVE-2026-27858?
This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2026-27858?
Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-27858?
CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-27858 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.
Related HIGH CVEs from 2026
View all- 8.9CVE-2026-23527
H3 is a minimal H(TTP) framework built for high performance and portability. Prior to 1.15.5, there
View details - 8.9CVE-2026-24772
OpenProject is an open-source, web-based project management software. To enable the real time collab
View details - 8.9CVE-2026-27169
OpenSift is an AI study tool that sifts through large datasets using semantic search and generative
View details - 8.9CVE-2026-25737
Budibase is a low code platform for creating internal tools, workflows, and admin panels. In 3.24.0
View details - 8.9CVE-2026-30934
FileBrowser Quantum is a free, self-hosted, web-based file manager. Prior to 1.3.1-beta and 1.2.2-st
View details - 8.9CVE-2026-31889
Shopware is an open commerce platform. Prior to 6.6.10.15 and 6.7.8.1, a vulnerability in the Shopwa
View details - 8.9CVE-2026-39328
ChurchCRM is an open-source church management system. Prior to 7.1.0, a stored cross-site scripting
View details - 8.9CVE-2025-40899
A Stored Cross-Site Scripting vulnerability was discovered in the Assets and Nodes functionality due
View details - 8.9CVE-2026-40487
Postiz is an AI social media scheduling tool. Prior to version 2.21.6, a file upload validation bypa
View details - 8.9CVE-2026-5921
A server-side request forgery (SSRF) vulnerability was identified in GitHub Enterprise Server that a
View details - 8.9CVE-2026-38949
Cross-Site Scripting (XSS) vulnerability exists in HTMLy version 3.1.1 in the content creation funct
View details - 8.9CVE-2026-5787
An Improper Certificate Validation in Ivanti EPMM before versions 12.6.1.1, 12.7.0.1, and 12.8.0.1 a
View details