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Apexward Pulse
Type Vulnerability

Onlyoffice · Path traversal

ONLYOFFICE Docs Server Path Traversal Vulnerability

1 sourceCVE-2021-3199

At a glance

High
Suggested 24-hour window, counted from the last update
ActiveConfirmed in-the-wild exploitation
Evidence-weighted, not popularity
Signal

Actively exploited in the wild — prioritise confirming exposure.

Why High

High rather than Critical: exposure is scored at a default because we cannot see your systems or suppliers. If you run or depend on Onlyoffice Document Server, treat it as Critical.

Briefing

There is no written leader briefing for this story yet. These questions come from the facts we hold.

Questions to ask IT

  • Do we run Onlyoffice Document Server, and is every instance on version 5.6.3 or later?
  • Is any of it reachable from the internet?
  • Have we checked whether it has already been used against us?
  • If it is still not patched, what mitigation is in place, and what is holding the fix up?

Next steps

  1. Confirm exposure and remediation status for affected products

Summary

  • ONLYOFFICE Docs contains a path traversal vulnerability that can occur when JWT is used, via a /.. Sequence in an image upload parameter and could allow for remote code execution.
  • CVE-2021-3199 is confirmed as exploited in the wild (US known-exploited catalogue).

Products and services involved

10 reports

Part of Gartner Report: The Attack Path is Closing Faster than Most Teams Can Patch

All 10 reports in this story

Pulse

Last checked 3d ago · Recheck overdue since 6 Nov 2026, 09:35 UK time

  1. Story8 Oct 2026, 20:02 UK time · 8 Oct

    Linked reporting from CISA (official authority).

    Read source (CISA Known Exploited Vulnerabilities)
  2. Update5 Nov 2026, 09:35 UK time · 3d ago

    held at 8.2%; ranking metadata was updated.

2 entries so far. The timeline chart appears once this story has more history.

Sources

How we know

Statements extracted from sources. Higher confidence means stronger corroboration.

  • ConfirmedHeadline90% confidence

    ONLYOFFICE Docs Server Path Traversal Vulnerability

  • ConfirmedSummary fact75% confidence

    ONLYOFFICE Docs contains a path traversal vulnerability that can occur when JWT is used, via a /.. Sequence in an image upload parameter and could allow for remote code execution.

  • ConfirmedCVE identifier95% confidence

    Event involves CVE-2021-3199

  • ConfirmedKnown-exploited catalogue98% confidence

    CVE-2021-3199 is confirmed as exploited in the wild (US known-exploited catalogue)

  • ConfirmedEstimated attack likelihood95% confidence

    CVE-2021-3199 has an estimated ~8.2% chance of attack in 30 days (94.8th percentile) as of 2026-10-08 — probability signal, not confirmed exploitation