CVE-2026-89789 (CVSS 7.8)

Description

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().

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CVSS v3.1 Score

7.8

HIGH

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

EPSS — Exploit Prediction

0.0021

Probability of exploitation

0.11%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

References

Other 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 https://git.kernel.org/stable/c/e3b9aa0773abd5d4ed90be41ce5306c146d5b09e https://git.kernel.org/stable/c/fcafb2b1430824bae4258c01a439ec97ca0c6973 https://git.kernel.org/stable/c/fd8396cfecbd904468c71362f08aaa25f96d5337

Frequently Asked Questions

What is 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(). It has a CVSS v3.1 base score of 7.8 (HIGH).

How severe is CVE-2026-89789? +

CVE-2026-89789 has a CVSS v3.1 score of 7.8 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0021, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-89789? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

CVE-2026-89789