CVE-2026-4247— FreeBSD 安全漏洞

TCP: remotely exploitable DoS vector (mbuf leak)

When a challenge ACK is to be sent tcp_respond() constructs and sends the challenge ACK and consumes the mbuf that is passed in. When no challenge ACK should be sent the function returns and leaks the mbuf. If an attacker is either on path with an established TCP connection, or can themselves establish a TCP connection, to an affected FreeBSD machine, they can easily craft and send packets which meet the challenge ACK criteria and cause the FreeBSD host to leak an mbuf for each crafted packet in excess of the configured rate limit settings i.e. with default settings, crafted packets in excess of the first 5 sent within a 1s period will leak an mbuf. Technically, off-path attackers can also exploit this problem by guessing the IP addresses, TCP port numbers and in some cases the sequence numbers of established connections and spoofing packets towards a FreeBSD machine, but this is harder to do effectively.

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在移除最后引用时对内存的释放不恰当(内存泄露)

FreeBSD 安全漏洞

FreeBSD是FreeBSD基金会的一套类Unix操作系统。 FreeBSD存在安全漏洞，该漏洞源于tcp_respond函数在不应发送挑战ACK时返回并泄漏mbuf，可能导致攻击者通过发送特制数据包使主机泄漏mbuf。

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