[showdoc/showdoc] Cross-site Scripting in ShowDoc

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

References

• https://nvd.nist.gov/vuln/detail/CVE-2022-0962
• https://github.com/star7th/showdoc/commit/3caa32334db0c277b84e993eaca2036f5d1dbef8
• https://huntr.dev/bounties/7ebe3e5f-2c86-44de-b83e-2ddb6bbda908
• https://github.com/advisories/GHSA-pccm-j6vj-jwwf