CVE-2026-89789 is a vulnerability in Linux Kernel
Published on September 16, 2026
gtp: add synchronize_net() in gtp_newlink() error path to prevent use-after-free
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().
Products Associated with CVE-2026-89789
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Affected Versions
Linux:- Version 459aa660eb1d8ce67080da1983bb81d716aa5a69 and below fcafb2b1430824bae4258c01a439ec97ca0c6973 is affected.
- Version 459aa660eb1d8ce67080da1983bb81d716aa5a69 and below 3ca3da5c305caa873ddb81e8c6b118143f6dd3d1 is affected.
- Version 459aa660eb1d8ce67080da1983bb81d716aa5a69 and below 6f815c2fb6ab20385f81c353cdad0ea3b88132af is affected.
- Version 459aa660eb1d8ce67080da1983bb81d716aa5a69 and below e3b9aa0773abd5d4ed90be41ce5306c146d5b09e is affected.
- Version 459aa660eb1d8ce67080da1983bb81d716aa5a69 and below fd8396cfecbd904468c71362f08aaa25f96d5337 is affected.
- Version 459aa660eb1d8ce67080da1983bb81d716aa5a69 and below 7677eb2cbf2cc7446de474c01a6b06277c0051e5 is affected.
- Version 459aa660eb1d8ce67080da1983bb81d716aa5a69 and below 8d85498016a5bb56339734a14c276209fa65bafc is affected.
- Version 459aa660eb1d8ce67080da1983bb81d716aa5a69 and below d989e22ae9802c52c56ad4284d0caf26696cf6ae is affected.
- Version 4.7 is affected.
- Before 4.7 is unaffected.
- Version 5.10.270, <= 5.10.* is unaffected.
- Version 5.15.221, <= 5.15.* is unaffected.
- Version 6.1.188, <= 6.1.* is unaffected.
- Version 6.6.157, <= 6.6.* is unaffected.
- Version 6.12.110, <= 6.12.* is unaffected.
- Version 6.18.52, <= 6.18.* is unaffected.
- Version 7.2.6, <= 7.2.* is unaffected.
- Version 7.3-rc1, <= * is unaffected.