hyper's HTTP header parser accepted, according to RFC 7230, illegal contents inside Content-Length headers.
Due to this, upstream HTTP proxies that ignore the header may still forward them along if it chooses to ignore the error.
To be vulnerable, hyper must be used as an HTTP/1 server and using an HTTP proxy upstream that ignores the header's contents
but still forwards it. Due to all the factors that must line up, an attack exploiting this vulnerability is unlikely.
hyper: Integer overflow in `hyper`'s parsing of the `Transfer-Encoding` header leads to data loss
When decoding chunk sizes that are too large, hyper's code would encounter an integer overflow. Depending on the situation,
this could lead to data loss from an incorrect total size, or in rarer cases, a request smuggling attack.
To be vulnerable, you must be using hyper for any HTTP/1 purpose, including as a client or server, and consumers must send
requests or responses that specify a chunk size greater than 18 exabytes. For a possible request smuggling attack to be possible,
any upstream proxies must accept a chunk size greater than 64 bits.
regex: Regexes with large repetitions on empty sub-expressions take a very long time to parse
The Rust Security Response WG was notified that the regex crate did not
properly limit the complexity of the regular expressions (regex) it parses. An
attacker could use this security issue to perform a denial of service, by
sending a specially crafted regex to a service accepting untrusted regexes. No
known vulnerability is present when parsing untrusted input with trusted
This issue has been assigned CVE-2022-24713. The severity of this vulnerability
is "high" when the regex crate is used to parse untrusted regexes. Other uses
of the regex crate are not affected by this vulnerability.
The regex crate features built-in mitigations to prevent denial of service
attacks caused by untrusted regexes, or untrusted input matched by trusted
regexes. Those (tunable) mitigations already provide sane defaults to prevent
attacks. This guarantee is documented and it's considered part of the crate's
Unfortunately a bug was discovered in the mitigations designed to prevent
untrusted regexes to take an arbitrary amount of time during parsing, and it's
possible to craft regexes that bypass such mitigations. This makes it possible
to perform denial of service attacks by sending specially crafted regexes to
services accepting user-controlled, untrusted regexes.
All versions of the regex crate before or equal to 1.5.4 are affected by this
issue. The fix is include starting from regex 1.5.5.
We recommend everyone accepting user-controlled regexes to upgrade immediately
to the latest version of the regex crate.
Unfortunately there is no fixed set of problematic regexes, as there are
practically infinite regexes that could be crafted to exploit this
vulnerability. Because of this, we do not recommend denying known problematic
We want to thank Addison Crump for responsibly disclosing this to us according
to the Rust security policy, and for helping review the fix.
We also want to thank Andrew Gallant for developing the fix, and Pietro Albini
for coordinating the disclosure and writing this advisory.