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CVE-2021-3199 is a directory traversal vulnerability in the image upload endpoint of ONLYOFFICE Document Server before version 5.6.3. When JSON Web Token (JWT) is used, a parent-directory traversal sequence in an image upload parameter can enable unauthorized writes and lead to remote code execution. Versions 5.1.5 through 5.6.2 are explicitly identified as affected, and successful exploitation has been reported in the wild.
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No public exploit code observed for this vulnerability.
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Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
19 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A path traversal flaw in ONLYOFFICE Docs involving an image-upload parameter when JWT is used, potentially allowing remote code execution. CISA added it to KEV following exploitation attributed to Flax Typhoon.
A known exploited vulnerability added to CISA's catalog in connection with the reported Chinese government-linked intrusion activity. The content does not describe its technical mechanism or affected product.
An ONLYOFFICE Document Server vulnerability successfully exploited in the reported activity, with applicability dependent on JWT usage. A fixed release is available.
A directory traversal vulnerability in the /upload endpoint of ONLYOFFICE Document Server versions before 5.6.3 can lead to remote code execution when JWT is used. The traversal is triggered through a /.. sequence in an image upload parameter. Public proof-of-concept exploit scripts are referenced.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.