CISA Adds ONLYOFFICE Docs Path Traversal to KEV
Tech GuruQuick Answer
CISA added CVE-2021-3199 affecting ONLYOFFICE Docs to KEV on October 8, confirming known exploitation. Inventory potentially affected deployments, validate versions against vendor guidance, apply supported mitigation by October 11, and retain investigation evidence.
Confirm Scope And Apply The Supported Fix
What to do now: Inventory ONLYOFFICE Docs, validate exact versions and exposure against vendor guidance, apply supported mitigation or discontinue use by 2026-10-11, and preserve triage evidence.
Last verified: 2026-10-09 UTC. Recheck the authoritative advisory and supported distribution channel before changing production.
Scope And Authority
| Product scope | ONLYOFFICE Docs |
|---|---|
| Advisory | CISA KEV: CVE-2021-3199 |
| CVE | CVE-2021-3199 |
| CISA KEV date added | 2026-10-08 |
| CISA catalog release timestamp | 2026-10-08 20:09:18.9833 UTC |
| Affected versions | CISA identifies ONLYOFFICE Docs for CVE-2021-3199 but does not enumerate affected versions in the KEV row; establish applicability from the linked vendor or project guidance. |
| Fixed version | Apply vendor mitigations under CISA BOD 26-04 guidance by 2026-10-11, or discontinue use if mitigations are unavailable |
| CVSS base score | Not provided by the authority |
| CVSS severity | Not provided by the authority |
| Exploitation status | Known exploited: confirmed by CISA KEV addition on 2026-10-08; no exploitation claim is inferred. |
What Changed
CISA added CVE-2021-3199 to the Known Exploited Vulnerabilities Catalog on 2026-10-08. 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.
What To Validate Now
- Inventory. Locate ONLYOFFICE Docs deployments, versions, enabled features, exposure paths, owners, and dependent services.
- Establish applicability. CISA identifies ONLYOFFICE Docs for CVE-2021-3199 but does not state affected versions in the KEV row. Use the linked vendor or project guidance; do not infer applicability from the product name alone.
- Remediate. Apply mitigations under the linked vendor guidance and CISA BOD 26-04 by 2026-10-11, or discontinue use if mitigations are unavailable.
- Validate. Confirm the resulting version or managed-service state, exercise representative functionality and recovery paths, monitor for regressions, and document exceptions.
- Retain evidence. Preserve asset and owner identifiers, the applicability decision, before-and-after versions, change approval, installation output, validation results, and any exception or rollback record.
Operational Cautions
CISA requires forensic triage for this entry. Known ransomware campaign use is listed as Unknown; do not infer ransomware use beyond that field. Preserve inventory, exposure, remediation, and incident-review evidence.
Evidence To Retain
- Exact product, release stream, package or application version, enabled feature, environment, and accountable owner.
- UTC timestamps, authority revision, approved change record, installer or package-manager output, and resulting version.
- Relevant logs and monitoring evidence, test results, exceptions, compensating controls, and rollback decisions.
Related TechGeeks Resources
Authoritative References
Correction policy: If the authority changes affected versions, fixed versions, severity, exploitation information, mitigations, or required action, TechGeeks will update this notice and its verification date.
