Previous versions of tracing-subscriber were vulnerable to ANSI escape sequence injection attacks. Untrusted user input containing ANSI escape sequences could be injected into terminal output when logged, potentially allowing attackers to:

• Manipulate terminal title bars
• Clear screens or modify terminal display
• Potentially mislead users through terminal manipulation

In isolation, impact is minimal, however security issues have been found in terminal emulators that enabled an attacker to use ANSI escape sequences via logs to exploit vulnerabilities in the terminal emulator.

This was patched in PR #3368 to escape ANSI control characters from user input.

In the unique reclaim path of BytesMut::reserve, the condition

if v_capacity >= new_cap + offset

uses an unchecked addition. When new_cap + offset overflows usize in release builds, this condition may incorrectly pass, causing self.cap to be set to a value that exceeds the actual allocated capacity. Subsequent APIs such as spare_capacity_mut() then trust this corrupted cap value and may create out-of-bounds slices, leading to UB.

This behavior is observable in release builds (integer overflow wraps), whereas debug builds panic due to overflow checks.

PoC

use bytes::*;

fn main() {
    let mut a = BytesMut::from(&b"hello world"[..]);
    let mut b = a.split_off(5);

    // Ensure b becomes the unique owner of the backing storage
    drop(a);

    // Trigger overflow in new_cap + offset inside reserve
    b.reserve(usize::MAX - 6);

    // This call relies on the corrupted cap and may cause UB & HBO
    b.put_u8(b'h');
}

Workarounds

Users of BytesMut::reserve are only affected if integer overflow checks are configured to wrap. When integer overflow is configured to panic, this issue does not apply.

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.

The h2 crate, used internally by hyper, had a flaw that would accept and queue empty DATA frames without limit. If streams were not actively drained, this could lead to unbounded memory usage, or a panic if the length overflows.

Low severity.

Patched in v0.4.16.