On Windows, configuring a named pipe server with pipe_mode will force ServerOptions::reject_remote_clients as false.

This drops any intended explicit configuration for the reject_remote_clients that may have been set as true previously.

The default setting of reject_remote_clients is normally true meaning the default is also overridden as false.

Workarounds

Ensure that pipe_mode is set first after initializing a ServerOptions. For example:

let mut opts = ServerOptions::new();
opts.pipe_mode(PipeMode::Message);
opts.reject_remote_clients(true);

When a Some(...) value was passed to the properties argument of either of these functions, a use-after-free would result.

In practice this would nearly always result in OpenSSL treating the properties as an empty string (due to CString::drop's behavior).

The maintainers thank quitbug for reporting this vulnerability to us.

Impact

When user-provided input is provided to any type that parses with the RFC 2822 format, a denial of service attack via stack exhaustion is possible. The attack relies on formally deprecated and rarely-used features that are part of the RFC 2822 format used in a malicious manner. Ordinary, non-malicious input will never encounter this scenario.

Patches

A limit to the depth of recursion was added in v0.3.47. From this version, an error will be returned rather than exhausting the stack.

Workarounds

Limiting the length of user input is the simplest way to avoid stack exhaustion, as the amount of the stack consumed would be at most a factor of the length of the input.

During message encoding, hickory-proto's BinEncoder stores pointers to labels that are candidates for name compression in a Vec<(usize, Vec<u8>)>. The name compression logic then searches for matches with a linear scan.

A malicious message with many records can both introduce many candidate labels, and invoke this linear scan many times. This can amplify CPU exhaustion in DoS attacks.

This is similar to CVE-2024-8508.

We recommend all affected users update to hickory-proto 0.26.1 for the fix.

The NSEC3 closest-encloser proof validation in hickory-net's DnssecDnsHandle walks from the QNAME up to the SOA owner name, building a list of candidate encloser names. The iterator used assumes the QNAME is a descendant of the SOA owner, terminating only when the current candidate equals the SOA name. When the SOA in a response's authority section is not an ancestor of the QNAME, the loop stalls at the DNS root and never terminates, repeatedly calling Name::base_name() and pushing newly allocated Name and hashed-name entries into the candidate Vec.

The bug is reachable by any caller of DnssecDnsHandle — including the resolver, recursor, and client — when built with the dnssec-ring or dnssec-aws-lc-rs feature and configured to perform DNSSEC validation. It is triggered while validating a NoData or NXDomain response whose authority section contains an SOA record from a zone other than an ancestor of the QNAME, on a code path that requires NSEC3 closest-encloser proof. In practice this can be reached through an insecure CNAME chain that crosses zone boundaries into a DNSSEC-signed zone returning NoData, but the minimum condition is just a mismatched SOA owner on a response requiring NSEC3 validation.

A debug_assert_ne!(name, Name::root()) guards the loop body, so debug builds abort with a panic on the first iteration past the root. Release builds compile the assertion out and run the loop unbounded, allocating until the process exhausts available memory (OOM). A reachable upstream attacker who can return such a response can therefore crash a debug-built validator or exhaust memory on a release-built one.

We recommend all affected users update to hickory-net 0.26.1 for the fix.