CVE-2021-26858
HIGHCVSS 7.8/10Actively ExploitedEPSS 89.51%
Last modified
CVE-2021-26858 is a high-severity vulnerability rated 7.8/10 on the CVSS scale. Microsoft Exchange Server Remote Code Execution Vulnerability. CISA has confirmed active exploitation in the wild. EPSS estimates a 89.51% chance of exploitation in the next 30 days.
Description
Microsoft Exchange Server Remote Code Execution Vulnerability
Metrics
Exploitation Status
This vulnerability is listed in CISA’s Known Exploited Vulnerabilities catalog, confirming active exploitation in the wild. Federal agencies must remediate by .
Affected Software
| Vendor | Product | Versions | Update |
|---|---|---|---|
| Microsoft | Exchange Server | 2013 | Cumulative Update 21 |
| Microsoft | Exchange Server | 2016 | Cumulative Update 10 |
| Microsoft | Exchange Server | 2019 | — |
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-26858Patch, Vendor Advisory
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26858Patch, Vendor Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-26858US Government Resource
Timeline
- Published
- Last Modified
- Status
- Analyzed
Frequently Asked Questions
What is CVE-2021-26858?
Microsoft Exchange Server Remote Code Execution Vulnerability
How severe is CVE-2021-26858?
CVE-2021-26858 has a CVSS score of 7.8/10 (HIGH severity). The EPSS model estimates a 89.51% probability of exploitation in the next 30 days. This vulnerability is listed in CISA's Known Exploited Vulnerabilities catalog.
How do I fix CVE-2021-26858?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.
How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
- Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
- PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
- AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.
Related CVEs from 2021
- CVE-2021-26843An issue was discovered in sthttpd through 2.27.1. On system…7.5
- CVE-2021-26844A cross-site scripting (XSS) vulnerability in Power Admin PA…5.4
- CVE-2021-26845Information Exposure vulnerability in Hitachi ABB Power Grid…7.5
- CVE-2021-26854Microsoft Exchange Server Remote Code Execution Vulnerabilit…6.6
- CVE-2021-26855Microsoft Exchange Server Remote Code Execution Vulnerabilit…9.1
- CVE-2021-26857Microsoft Exchange Server Remote Code Execution Vulnerabilit…7.8
- CVE-2021-26859Microsoft Power BI Information Disclosure Vulnerability7.7
- CVE-2021-26860Windows App-V Overlay Filter Elevation of Privilege Vulnerab…7.8
- CVE-2021-26861Windows Graphics Component Remote Code Execution Vulnerabili…7.8
- CVE-2021-26862Windows Installer Elevation of Privilege Vulnerability7
- CVE-2021-26863Windows Win32k Elevation of Privilege Vulnerability7
- CVE-2021-26864Windows Virtual Registry Provider Elevation of Privilege Vul…8.4
Are you affected by CVE-2021-26858?
Run a free Strix scan to check your systems for this vulnerability.
Scan your code nowSource: NVD / NIST