A file extension handling issue was found in [core] module of ONLYOFFICE DocumentServer…
Priority MEDIUM 56Published · 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 v4.2.0.236-v5.6.4.13. An attacker must request the conversion of the crafted file from DOCT into DOCX format. Using the chain of two other bugs related to improper string handling, an attacker can achieve remote code execution on DocumentServer.
Why it matters now
EPSS 0.11763 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:*:*:*:*:*:*:*:* | 4.2.0.236 – 5.6.4.13 | Vulnerable | ONLYOFFICE |
- cpe:2.3:a:onlyoffice:document_server:*:*:*:*:*:*:*:* Versions 4.2.0.236 – 5.6.4.13 Vulnerable ·ONLYOFFICE
Remediation
No fixed version listed by the sources yet.
Timeline
- 2026-10-02 Threatist record created from CVE-2021-25830
- 2026-10-03 Alias added: GHSA-5mvf-vvh4-mj9c
References
Advisory 3
- https://github.com/ONLYOFFICE/core/blob/v5.6.4.13/ASCOfficePPTXFile/PPTXFormat/Logic/UniFill.cpp#L343
- 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
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-2021-25830 · CVE Program
- CVE-2021-25830 · NVD
- FIRST EPSS
- GHSA-5mvf-vvh4-mj9c · GitHub Advisory Database · CC BY 4.0
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