[showdoc/showdoc] Cross-site Scripting in ShowDoc

ShowDoc prior to 2.10.4 is vulnerable to stored cross-site scripting via .webmv file upload.

References

• https://nvd.nist.gov/vuln/detail/CVE-2022-0964
• https://github.com/star7th/showdoc/commit/3caa32334db0c277b84e993eaca2036f5d1dbef8
• https://huntr.dev/bounties/dbe39998-8eb7-46ea-997f-7b27f6f16ea0
• https://github.com/advisories/GHSA-xm3x-787m-p66r