A file extension handling issue was found in [core] module of ONLYOFFICE DocumentServer…
Priority MEDIUM 55Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- No fix listed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA.
Summary
A file extension handling issue was found in [core] module of ONLYOFFICE DocumentServer v4.0.0-9-v5.6.3. An attacker must request the conversion of the crafted file from PPTT into PPTX format. Using the chain of two other bugs related to improper string handling, a remote attacker can obtain remote code execution on DocumentServer.
Why it matters now
EPSS 0.11503 96th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix No fix listed No fixed version in the sources yet
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | — | all versions | — | No fix listed | CNA |
- — Vendor— Affected all versions Fixed in — No fix listed CNA
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:onlyoffice:document_server:*:*:*:*:*:*:*:* | 4.0.0-9 – 5.6.3 | Vulnerable | ONLYOFFICE |
- cpe:2.3:a:onlyoffice:document_server:*:*:*:*:*:*:*:* Versions 4.0.0-9 – 5.6.3 Vulnerable ·ONLYOFFICE
Remediation
No fixed version listed by the sources yet.
Timeline
- 2026-10-02 Threatist record created from CVE-2021-25831
- 2026-10-03 Alias added: GHSA-m252-hx7q-7p3h
References
Advisory 4
- https://github.com/ONLYOFFICE/core
- https://github.com/ONLYOFFICE/core/blob/v5.6.4.13/ASCOfficePPTXFile/Editor/BinaryFileReaderWriter.cpp#L241
- https://github.com/ONLYOFFICE/core/blob/v5.6.4.13/ASCOfficePPTXFile/Editor/BinaryFileReaderWriter.cpp#L1918
- https://github.com/ONLYOFFICE/core/blob/v5.6.4.13/ASCOfficePPTXFile/PPTXFormat/Logic/Fills/BlipFill.cpp#L328
More ONLYOFFICE Document Server vulnerabilities
- TI-2021-02273 Path traversal in ONLYOFFICE Document Server enables code execution KEVCVSS 3.1CRITICAL 9.8
- TI-2023-14162 An out of bounds memory access vulnerability in ONLYOFFICE DocumentServer 4.0.3 through… CVSS 3.1CRITICAL 9.8
- TI-2023-14161 A use after free issue discovered in ONLYOFFICE DocumentServer 4.0.3 through 7.3.2 allows… CVSS 3.1CRITICAL 9.8
- TI-2023-14163 Memory Exhaustion vulnerability in ONLYOFFICE Document Server 4.0.3 through 7.3.2 allows… CVSS 3.1HIGH 7.5
- TI-2021-07886 A file extension handling issue was found in [server] module of ONLYOFFICE DocumentServer… CVSS 3.1CRITICAL 9.8
- TI-2023-25368 Path Traversal vulnerability in ONLYOFFICE Document Server before v8.0.1 allows a remote… CVSS 3.1MEDIUM 6.7
Sources
- CVE-2021-25831 · CVE Program
- CVE-2021-25831 · NVD
- FIRST EPSS
- GHSA-m252-hx7q-7p3h · GitHub Advisory Database · CC BY 4.0
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