Impact

When calling DefaultHttpHeaders.set with an iterator of values (as opposed to a single given value), header value validation was not performed, allowing malicious header values in the iterator to perform HTTP Response Splitting.

Patches

The necessary validation was added in Netty 4.1.86.Final.

Workarounds

Integrators can work around the issue by changing the DefaultHttpHeaders.set(CharSequence, Iterator<?>) call, into a remove() call, and call add() in a loop over the iterator of values.

References

HTTP Response Splitting
CWE-113: Improper Neutralization of CRLF Sequences in HTTP Headers

For more information

If you have any questions or comments about this advisory:

• Open an issue in [example link to repo](https://github.com/netty/netty)
• Email us at netty-security@googlegroups.com