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CVE-2026-23460: net/rose: fix NULL pointer dereference in rose_transmit_link on reconnect

• Severity: medium (CVSS 5.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-04-03 · updated 2026-07-24
• Weakness: CWE-476

Description

In the Linux kernel, the following vulnerability has been resolved: net/rose: fix NULL pointer dereference in rose_transmit_link on reconnect syzkaller reported a bug [1], and the reproducer is available at [2]. ROSE sockets use four sk->sk_state values: TCP_CLOSE, TCP_LISTEN, TCP_SYN_SENT, and TCP_ESTABLISHED. rose_connect() already rejects calls for TCP_ESTABLISHED (-EISCONN) and TCP_CLOSE with SS_CONNECTING (-ECONNREFUSED), but lacks a check for TCP_SYN_SENT. When rose_connect() is called a second time while the first connection attempt is still in progress (TCP_SYN_SENT), it overwrites rose->neighbour via rose_get_neigh(). If that returns NULL, the socket is left with rose->state == ROSE_STATE_1 but rose->neighbour == NULL. When the socket is subsequently closed, rose_release() sees ROSE_STATE_1 and calls rose_write_internal() -> rose_transmit_link(skb, NULL), causing a NULL pointer dereference. Per connect(2), a second connect() while a connection is already in progress should return -EALREADY. Add this missing check for TCP_SYN_SENT to complete the state validation in rose_connect(). [1] https://syzkaller.appspot.com/bug?extid=d00f90e0af54102fb271 [2] https://gist.github.com/mrpre/9e6779e0d13e2c66779b1653fef80516

Affected products

• Linux kernel: from 2.6.12.1 before 5.10.253; from 5.11 before 5.15.203; from 5.16 before 6.1.167; from 6.2 before 6.6.130; from 6.7 before 6.12.78; from 6.13 before 6.18.20 — fixed in 5.10.253, 5.15.203, 6.1.167, 6.12.78, 6.18.20, 6.19.10

How to fix

Upgrade to a fixed version: Linux kernel 5.10.253, 5.15.203, 6.1.167, 6.12.78. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/0c3e8bff808f17ad37a51d8e719eed22c7863120
• https://git.kernel.org/stable/c/0c9fb70a206a8734e10468ecc24d57c7596cf64e
• https://git.kernel.org/stable/c/508f49ccbe0329641bb681f7d0052bb4e5943252
• https://git.kernel.org/stable/c/a12254050e3050f1011cd24f3b880a6882d0139d
• https://git.kernel.org/stable/c/a753844d2a8136f090123c8fb1ff6c7f6ee7c2b3
• https://git.kernel.org/stable/c/c2ab74c12932e52cfa1e7e4582d42b0c8bec96c7
• https://git.kernel.org/stable/c/c85fe6580e86947ca07907ebf4363a73c156fda7
• https://git.kernel.org/stable/c/e1f0a18c9564cdb16523c802e2c6fe5874e3d944

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