In versions prior 0.11.3 it's possible to make from_slice panic by feeding it certain malformed input. It's never documented that from_slice (and from_bytes which wraps it) can panic, and its' return type (Result<Self, DecodeError>) suggests otherwise.

In practice, from_slice/from_bytes is frequently used in networking code (for example in rust-libp2p) and is being called with unsanitized data from untrusted sources. This can allow attackers to cause DoS by causing an unexpected panic in the network client's code.

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 regexes.

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.

Overview

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 API.

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.

Affected versions

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.

Mitigations

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 regexes.

Acknowledgements

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.

When this function was passed an empty string, openssl would attempt to call strlen on it, reading arbitrary memory until it reached a NUL byte.

The Tungstenite crate through 0.20.0 for Rust allows remote attackers to cause a denial of service (minutes of CPU consumption) via an excessive length of an HTTP header in a client handshake. The length affects both how many times a parse is attempted (e.g., thousands of times) and the average amount of data for each parse attempt (e.g., millions of bytes).