CVE-2026-89789

In the Linux kernel, the following vulnerability has been resolved: gtp: add synchronize_net() in gtp_newlink() error path to prevent use-after-free gtp_newlink()'s error path frees tid_hash and addr_hash without waiting for an RCU grace period after clearing sk_user_data. A concurrent gtp_encap_recv() in softirq may still hold the gtp_dev pointer obtained via rcu_dereference_sk_user_data() and access the freed memory. BUG: KASAN: slab-use-after-free in gtp0_pdp_find+0x1f6/0x200 (gtp.c:152) Call Trace: <IRQ> gtp0_pdp_find+0x1f6/0x200 gtp_encap_recv+0x527/0x24b0 udp_queue_rcv_one_skb+0x75f/0xc10 Add synchronize_net() before the kfree calls in out_hashtable, which covers all error paths from both gtp_encap_enable() and gtp_create_sockets().

CVSS 3.1

7.8CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS

0.2% chance of exploitation in the next 30 days; higher than 5% of CVEs (scores of 2026-10-25)

Published

2026-09-16

Modified

2026-10-19

Record from

the NVD, synced 2026-10-19

References

• https://git.kernel.org/stable/c/3ca3da5c305caa873ddb81e8c6b118143f6dd3d1
• https://git.kernel.org/stable/c/6f815c2fb6ab20385f81c353cdad0ea3b88132af
• https://git.kernel.org/stable/c/7677eb2cbf2cc7446de474c01a6b06277c0051e5
• https://git.kernel.org/stable/c/8d85498016a5bb56339734a14c276209fa65bafc
• https://git.kernel.org/stable/c/d989e22ae9802c52c56ad4284d0caf26696cf6ae

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