Vulnerability in Onlyoffice Document Server
CVE-2021-25831
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.115 (95.9th percentile), scored .
Moderate probability of exploitation in the next 30 days — watch for active exploitation reports. 96th percentile — 95.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.115 · newest: 0.115 · change: 0.000
Affected products
Public proof-of-concept exploits
References
- github.com/ONLYOFFICE/DocumentServer (Product)
- github.com/ONLYOFFICE/core (Product, Vendor Advisory)
- github.com/ONLYOFFICE/core/blob/v5.6.4.13/ASCOfficePPTXFile/Editor/BinaryFileRe… (Vendor Advisory)
- github.com/ONLYOFFICE/core/blob/v5.6.4.13/ASCOfficePPTXFile/Editor/BinaryFileRe… (Vendor Advisory)
- github.com/ONLYOFFICE/core/blob/v5.6.4.13/ASCOfficePPTXFile/PPTXFormat/Logic/Fi… (Vendor Advisory)
- github.com/merrychap/poc_exploits/tree/master/ONLYOFFICE/CVE-2021-25831 (Exploit, Vendor Advisory)
Frequently asked questions
- What is CVE-2021-25831?
- CVE-2021-25831 is a critical-severity vulnerability in Onlyoffice Document Server. CVSS score: 9.8/10. Published 2021-03-01.
- How severe is CVE-2021-25831?
- Critical severity. CVSS v3 base score is 9.8 out of 10.
- Is CVE-2021-25831 known to be exploited?
- 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.