CVE-2026-41034Network attack vector

Authenticated memory disclosure via crafted XLS records

Published Apr 16, 2026 · Updated Apr 16, 2026

Out-of-bounds read in ONLYOFFICE DocumentServer before 9.3.0 allows remote authenticated users to disclose process memory through crafted XLS files. During XLS processing, the converter dereferences untrusted pointer-related record data, including pictFmla.cbBufInCtlStm, outside the intended buffer. A user able to submit a spreadsheet for conversion can obtain an information leak that weakens ASLR; no write or service interruption is reported.

CVSS severity5.0
Medium
EPSS probability0.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in ONLYOFFICE DocumentServer before 9.3.0 allows remote authenticated users to disclose process memory through crafted XLS files. During XLS processing, the converter dereferences untrusted pointer-related record data, including pictFmla.cbBufInCtlStm, outside the intended buffer. A user able to submit a spreadsheet for conversion can obtain an information leak that weakens ASLR; no write or service interruption is reported.

The record

CVE
CVE-2026-41034
Published
Apr 16, 2026
Updated
Apr 16, 2026
Vendor
Ascensio System SIA
Product
ONLYOFFICE Docs
Classifications
CWE-125, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 16, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 16, 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=0 <9.3.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Ascensio System SIA · ONLYOFFICE Docsversion=0 <9.3.0

Published CVSS scores

5.0MITRECVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/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.

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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

CWE-125Out-of-bounds Read
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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