cbcvebase.
CVE-2025-21710
published 2025-02-27

CVE-2025-21710: In the Linux kernel, the following vulnerability has been resolved: tcp: correct handling of extreme memory squeeze Testing with iperf3 using the "pasta"…

PriorityP421medium5.5CVSS 3.1
AVLACLPRLUINSUCNINAH
EPSS
0.26%
17.9th percentile
In the Linux kernel, the following vulnerability has been resolved: tcp: correct handling of extreme memory squeeze Testing with iperf3 using the "pasta" protocol splicer has revealed a problem in the way tcp handles window advertising in extreme memory squeeze situations. Under memory pressure, a socket endpoint may temporarily advertise a zero-sized window, but this is not stored as part of the socket data. The reasoning behind this is that it is considered a temporary setting which shouldn't influence any further calculations. However, if we happen to stall at an unfortunate value of the current window size, the algorithm selecting a new value will consistently fail to advertise a non-zero window once we have freed up enough memory. This means that this side's notion of the current window size is different from the one last advertised to the peer, causing the latter to not send any data to resolve the sitution. The problem occurs on the iperf3 server side, and the socket in question is a completely regular socket with the default settings for the fedora40 kernel. We do not use SO_PEEK or SO_RCVBUF on the socket. The following excerpt of a logging session, with own comments added, shows more in detail what is happening: // tcp_v4_rcv(->) // tcp_rcv_established(->) [520139222]: ==== Activating log @ net/ipv4/tcp_input.c/tcp_data_queue()/5257 ==== [520139222]: tcp_data_queue(->) [520139222]: DROPPING skb [265600160..265665640], reason: SKB_DROP_REASON_PROTO_MEM [rcv_nxt 265600160, rcv_wnd 262144, snt_ack 265469200, win_now 131184] [copied_seq 259909392->260034360 (124968), unread 5565800, qlen 85, ofoq 0] [OFO queue: gap: 65480, len: 0] [520139222]: tcp_data_queue(39222]: __tcp_transmit_skb(->) [tp->rcv_wup: 265469200, tp->rcv_wnd: 262144, tp->rcv_nxt 265600160] [520139222]: tcp_select_window(->) [520139222]: (inet_csk(sk)->icsk_ack.pending & ICSK_ACK_NOMEM) ? --> TRUE [tp->rcv_wup: 265469200, tp->rcv_wnd: 262144, tp->rcv_nxt 265600160] returning 0 [520139222

Affected

12 ranges
VendorProductVersion rangeFixed in
debianlinux< linux 6.12.13-1 (forky)linux 6.12.13-1 (forky)
linuxlinux
linuxlinux>= e2142825c120d4317abf7160a0fc34b3de532586 < b01e7ceb35dcb7ffad413da657b78c3340a09039b01e7ceb35dcb7ffad413da657b78c3340a09039
linuxlinux>= e2142825c120d4317abf7160a0fc34b3de532586 < 1dd823a46e25ffde1492c391934f69a9e5eb574f1dd823a46e25ffde1492c391934f69a9e5eb574f
linuxlinux>= e2142825c120d4317abf7160a0fc34b3de532586 < b4055e2fe96f4ef101d8af0feb056d78d77514ffb4055e2fe96f4ef101d8af0feb056d78d77514ff
linuxlinux>= e2142825c120d4317abf7160a0fc34b3de532586 < 8c670bdfa58e48abad1d5b6ca1ee843ca91f73038c670bdfa58e48abad1d5b6ca1ee843ca91f7303
linuxlinux_kernel>= 0 < 6.12.13-16.12.13-1
linuxlinux_kernel>= 0 < 6.12.13-16.12.13-1
linuxlinux_kernel>= 0 < 6.8.0-64.676.8.0-64.67
linuxlinux_kernel>= 6.13 < 6.13.26.13.2
linuxlinux_kernel>= 6.6 < 6.6.766.6.76
linuxlinux_kernel>= 6.7 < 6.12.136.12.13

CVSS provenance

nvdv3.15.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
osv7.8HIGH
vendor_ubuntu7.8HIGH
vendor_debian5.5LOW
vendor_redhat5.5MEDIUM
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