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CVE-2021-26857 CISA KEV · Actively exploitedLinked to ransomware

Microsoft Exchange Server Remote Code Execution Vulnerability

CVSS score

7.8

EPSS probability

%95.8

Risk score

14.9

Published

5 y ago

OverviewPublic Exploits (0)NewsroomVulnerability Timeline
Official patch verified

Etkilenen ürün ve sürüm için yayımlanan güvenlik güncellemesini uygulayın.

Impact on My Inventory

Only the personal products you have added to your account are assessed; an organisation's inventory does not appear here.

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Vulnerability description

DayBreach CVE AI Research

CVE-2021-26857 has vendor, distribution, patch and security-source records on file. We can compare them and prepare an explanation linked to the evidence.

Microsoft Exchange Server Remote Code Execution Vulnerability

IMPACT: Affected Products and Software

Affected Products

The following products are affected by CVE-2021-26857 vulnerability. Where our threat engine knows the exact affected versions, they are listed below.

IDVENDORPRODUCTACTION
1microsoftMicrosoft Exchange Server 2010 Service Pack 3 View
2microsoftMicrosoft Exchange Server 2013 Cumulative Update 21 View
3microsoftMicrosoft Exchange Server 2013 Cumulative Update 22 View
4microsoftMicrosoft Exchange Server 2013 Cumulative Update 23 View
5microsoftMicrosoft Exchange Server 2013 Service Pack 1 View
6microsoftMicrosoft Exchange Server 2016 Cumulative Update 10 View
7microsoftMicrosoft Exchange Server 2016 Cumulative Update 11 View
8microsoftMicrosoft Exchange Server 2016 Cumulative Update 12 View
9microsoftMicrosoft Exchange Server 2016 Cumulative Update 13 View
10microsoftMicrosoft Exchange Server 2016 Cumulative Update 14 View
11microsoftMicrosoft Exchange Server 2016 Cumulative Update 15 View
12microsoftMicrosoft Exchange Server 2016 Cumulative Update 16 View
13microsoftMicrosoft Exchange Server 2016 Cumulative Update 17 View
14microsoftMicrosoft Exchange Server 2016 Cumulative Update 18 View
15microsoftMicrosoft Exchange Server 2016 Cumulative Update 19 View
16microsoftMicrosoft Exchange Server 2016 Cumulative Update 8 View
17microsoftMicrosoft Exchange Server 2016 Cumulative Update 9 View
18microsoftMicrosoft Exchange Server 2019 View
19microsoftMicrosoft Exchange Server 2019 Cumulative Update 1 View
20microsoftMicrosoft Exchange Server 2019 Cumulative Update 2 View
21microsoftMicrosoft Exchange Server 2019 Cumulative Update 3 View
22microsoftMicrosoft Exchange Server 2019 Cumulative Update 4 View
23microsoftMicrosoft Exchange Server 2019 Cumulative Update 5 View
24microsoftMicrosoft Exchange Server 2019 Cumulative Update 6 View
25microsoftMicrosoft Exchange Server 2019 Cumulative Update 7 View
26microsoftMicrosoft Exchange Server 2019 Cumulative Update 8 View
27microsoftexchange server View
28microsoftexchange server View
29microsoftexchange server View
30microsoftexchange server View
Total affected vendors: 1|Products: 30

RED HAT CSAF/VEX: Product Impact Check

Red Hat has not yet published a CSAF/VEX impact record for this CVE. This does not mean “not affected”.

SCORING: CVSS from Multiple Sources

CVSS Scores

The Common Vulnerability Scoring System is a standardised framework for assessing the severity of vulnerabilities in software and systems. We collect and display CVSS scores from several sources for each CVE.

SCOREVERSIONSEVERITYVECTORSOURCE
7.8CVSS V3_1HIGHCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:F/RL:O/RC:CCVE CNA
7.8CVSS V31HIGHCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:HNVD
6.8CVSS V2—AV:N/AC:M/Au:N/C:P/I:P/A:PNVD

Patch and Remediation Guide

Solution & Remediation Advisory

Patch verified

5 doğrulanmış yama veya düzeltilmiş sürüm kanıtı bulundu.

cvelist

Microsoft Exchange Server Remote Code Execution Vulnerability

Open source
nvd

NVD tarafından Patch olarak etiketlenmiş referans

Open source
nvd

NVD tarafından Patch olarak etiketlenmiş referans

Open source
reference

Microsoft Exchange Server Remote Code Execution Vulnerability

Open source
reference

Yama veya çözüm referansı

Open source
canonical

Apply updates per vendor instructions.

Confirm the affected product and version against the source evidence above.
Restrict access to internet-facing services and apply network segmentation.
Apply the official update named in the evidence only to the matching product and version.
Monitor server logs and network endpoints for signs of anomalous execution.

Public exploit and active exploitation status

Verified exploit intelligence

This CVE is marked as actively exploited in the CISA KEV catalogue, but no verified, downloadable public PoC or Metasploit module has been found yet. Evidence of active exploitation does not mean that public exploit code exists.

Weakness Classification and Attack Patterns (CWE & CAPEC)

CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2021-26857 is associated with the following CWEs:

CWE-502: Deserialization of Untrusted Data

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2021-26857 weaknesses.

CAPEC-66: SQL InjectionCAPEC-126: Path TraversalCAPEC-28: OS Command Injection

Attack Vector and Accessibility

ExposureYerel erişim
PermissionsGerekmiyor
UserGerekiyor

Official Sources and Advisories

Microsoft Exchange Server Remote Code Execution Vulnerabilitypatchhttps://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26857patchhttps://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-26857nvdCISA Known Exploited Vulnerabilities Catalogkev

CVSS Vector Radar Chart

7.8 / 10
Attack VectorLocalComplexityLowPrivilegesNoneUser Interact.RequiredConfidentialityLowIntegrityHighAvailabilityHigh

Vulnerability Scoring Details

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C
Attack VectorLocal
Attack ComplexityLow
Privileges RequiredNone required
User Interaction—
Confidentiality (Gizlilik)Low
Integrity (Bütünlük)High
Availability (Erişilebilirlik)High

Yama doğrulandı

5 doğrulanmış yama veya düzeltilmiş sürüm kanıtı bulundu.

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Weakness Type (CWE & CAPEC)

CWE-502

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