According to the updated description, this stored cross‑site scripting flaw resides in Deer‑Flow's artifacts API, allowing an attacker to upload malicious HTML or script content that is rendered in the browser when other users view the artifacts. The injected code can execute in the victim’s browser context, potentially compromising their session, stealing credentials, or enabling arbitrary JavaScript execution.

Bytedance Inc. Deer‑Flow instances running any version prior to the commit identified as 5dbb362 are affected. No further version granularity is supplied, so all releases before that patch are considered vulnerable.

The CVSS base score of 5.1 indicates moderate severity. The EPSS score of approximately 0.035% reflects a very low exploitation probability, and the vulnerability is not listed in the CISA KEV catalog. The likely attack vector is through the artifact upload API; an attacker can submit malicious content that is later rendered to end users in the browser. Because the attack requires only an upload privilege and the content is stored and rendered without adequate sanitization, exploitation is feasible even without privileged access.