CyberRota Analysis
AI-GeneratedUnbound versions 1.22.0 through 1.26.1, when compiled with DNS-over-QUIC support, contain a use-after-free vulnerability that can be exploited by an attacker who can send queries to the server. This flaw allows the attacker to trigger retransmissions from freed memory, potentially causing the server to crash after a series of crafted queries. Organizations using affected versions of Unbound should prioritize patching this vulnerability to mitigate the risk of service disruption.
Original NVD Description
NLnet Labs Unbound 1.22.0 up to and including 1.26.1, has a use-after-free vulnerability when compiled for DNS-over-QUIC support with '--with-libngtcp2'. Each DoQ stream owns an output buffer that holds the DNS response. ngtcp2's retransmission buffer keeps a shallow pointer into the output buffer for as long as a STREAM frame may be resent. On a client RESET_STREAM, the output buffer is freed but ngtcp2 still holds the matching retransmission entries. The next PTO timeout makes ngtcp2 re-encode the STREAM frame and copy from the freed buffer. A malicious actor that can query Unbound over DoQ and that withholds ACKs, sends RESET_STREAM, and waits for PTO, reaches this use-after-free with no privilege. This leads to retransmissions against freed memory and eventually an abnormal server exit under a 20-query spray.
Related CVEs
Other vulnerabilities affecting the same vendor(s)