HHVM supports the use of an "admin" server which accepts administrative requests over HTTP. One of those request handlers, dump-pcre-cache, can be used to output cached regular expressions from the current execution context into a file. The handler takes a parameter which specifies where on the filesystem to write this data. The parameter is not validated, allowing a malicious user to overwrite arbitrary files where the user running HHVM has write access. This issue affects HHVM versions prior to 4.56.2, all versions between 4.57.0 and 4.78.0, as well as 4.79.0, 4.80.0, 4.81.0, 4.82.0, and 4.83.0.
The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.
| Link | Tags |
|---|---|
| https://hhvm.com/blog/2020/11/12/security-update.html | vendor advisory |
| https://github.com/facebook/hhvm/commit/abe0b29e4d3a610f9bc920b8be4ad8403364c2d4 | third party advisory patch |
| https://www.facebook.com/security/advisories/cve-2019-3556 | broken link |