Inefficient Regular Expression Complexity in marked
### Impact
_What kind of vulnerability is it?_
Denial of service.
The regular expression `block.def` may cause catastrophic backtracking against some strings.
PoC is the following.
```javascript
import * as marked from "marked";
marked.parse(`[x]:${' '.repeat(1500)}x ${' '.repeat(1500)} x`);
```
_Who is impacted?_
Anyone who runs untrusted markdown through marked and does not use a worker with a time limit.
### Patches
_Has the problem been patched?_
Yes
_What versions should users upgrade to?_
4.0.10
### Workarounds
_Is there a way for users to fix or remediate the vulnerability without upgrading?_
Do not run untrusted markdown through marked or run marked on a worker
https://marked.js.org/using_advanced#workers thread and set a reasonable time limit to prevent draining resources.
### References
_Are there any links users can visit to find out more?_
-
https://marked.js.org/using_advanced#workers
-
https://owasp.org/www-community/attacks/Regular_expression_Denial_of_Service_-_ReDoS
### For more information
If you have any questions or comments about this advisory:
* Open an issue in marked
https://github.com/markedjs/marked