CVE-2021-26859Network attack vector

Report-server credential disclosure via remote file path

Published Mar 11, 2021 · Updated Aug 19, 2026

Information disclosure in Microsoft Power BI Report Server allows remote authenticated users to obtain report-server credentials. An internal API for large PBIX-file requests accepts a caller-supplied file-path property, causing Reporting Services to write a temporary file to a remote path and send the service account's NTLM credential material. Exploitation requires authenticated API access and control of the remote destination; the disclosed hash must then be cracked to recover the service credentials.

CVSS severity7.7
High
EPSS probability3.04%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in Microsoft Power BI Report Server allows remote authenticated users to obtain report-server credentials. An internal API for large PBIX-file requests accepts a caller-supplied file-path property, causing Reporting Services to write a temporary file to a remote path and send the service account's NTLM credential material. Exploitation requires authenticated API access and control of the remote destination; the disclosed hash must then be cracked to recover the service credentials.

The record

CVE
CVE-2021-26859
Published
Mar 11, 2021
Updated
Aug 19, 2026
Vendor
Microsoft
Product
Power BI Report Server
Classifications
T1187
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 11, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 19, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=15.0.0.0 <1.8.7485.35104
  2. Affected versionversion=15.0.0.0 <1.9.7675.15620

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Microsoft · Power BI Report Serverversion=15.0.0.0 <1.8.7485.35104; version=15.0.0.0 <1.9.7675.15620

Published CVSS scores

7.7MicrosoftCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
4.0NVDAV:N/AC:L/Au:S/C:P/I:N/A:N
6.5NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1187Forced Authentication

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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