ONLYOFFICE all versions as of 2021-11-08 is vulnerable to Improper Input Validation.

published 2023-01-23 3y ago modified 2026-06-17 4mo ago also EUVD-2021-30381

cvss: 5.3; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 1.0%; EPSS 1.0% chance of exploitation in 30 days, percentile 63%
public exploits: 0; none known

ONLYOFFICE all versions as of 2021-11-08 is vulnerable to Improper Input Validation. A lack of input validation can allow an attacker to spoof the names of users who interact with a document, if the document id is known.

Is CVE-2021-43448 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: partial
Assessed: last yr. (2025-04-02)

Exploit prediction

1.03% chance of exploitation in the next 30 days, higher than 63% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

labs.nettitude.com https://labs.nettitude.com/blog/exploiting-onlyoffice-web-sockets-for-unauthenticated-remote-code-execution/ referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CISA ADP	3.1	5.3	CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N
NVD	3.1	5.3	CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N
CNA	3.1	5.3	CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N

Classification

Weakness

CWE-20 Improper Input Validation

References

labs.nettitude.com /blog/exploiting-onlyoffice-web-sockets-for-unauthenticated-remote-code-execution/
exploit, mitigation, third-party-advisory
onlyoffice.com /
product, vendor-advisory
github.com /ONLYOFFICE/server
third-party-advisory

Sources

CVE List CVE-2021-43448
NVD CVE-2021-43448

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.