CVE-2026-64188 Linux vulnerability
In the Linux kernel, the following vulnerability has been resolved: net: qualcomm: rmnet: fix endpoint use-after-free in rmnet_dellink() rmnet_dellink() removes the endpoint from the hash table with hlist_del_init_rcu() and then immediately frees it with kfree(). However, RCU readers on the receive path (rmnet_rx_handler -> __rmnet_map_ingress_handler) may still hold a reference to the endpoint and dereference ep->egress_dev after the memory has been freed. The endpoint is a kmalloc-32 object, and the stale read at offset 8 corresponds to the egress_dev pointer. BUG: unable to handle page fault for address: ffffffffde942eef Oops: 0002 [#1] SMP NOPTI CPU: 1 UID: 0 PID: 137 Comm: poc_write Not tainted 7.0.0+ #4 PREEMPTLAZY RIP: 0010:rmnet_vnd_rx_fixup (rmnet_vnd.c:27) Call Trace: <TASK> __rmnet_map_ingress_handler (rmnet_handlers.c:48 rmnet_handlers.c:101) rmnet_rx_handler (rmnet_handlers.c:129 rmnet_handlers.c:235) __netif_receive_skb_core.constprop.0 (net/core/dev.c:6096) __netif_receive_skb_one_core (net/core/dev.c:6208) netif_receive_skb (net/core/dev.c:6467) tun_get_user (drivers/net/tun.c:1955) tun_chr_write_iter (drivers/net/tun.c:2003) vfs_write (fs/read_write.c:688) ksys_write (fs/read_write.c:740) </TASK> Add an rcu_head field to struct rmnet_endpoint and replace kfree() with kfree_rcu() so the endpoint memory remains valid through the RCU grace period. Also remove the rmnet_vnd_dellink() call and inline only the nr_rmnet_devs decrement, since rmnet_vnd_dellink() would set ep->egress_dev to NULL during the grace period, creating a data race with lockless readers.
Browse Linux security risksQuick answer
Linux should be reviewed and updated if it matches the affected versions. The recommended fix is to apply the vendor-supported patched version or the mitigation steps below, then retest the public website with Fixnx.
Who is affected
Affected versions
- < c4e676c3505c5058922dc1a6f1ded795f6758135
- < 9918698cf3aee4032e12bb42fd5a951dc465339b
- < 310b93246bfec7d4452507e0c15477377ed9f025
- < 1078ae8175777e80c9637996fb4a46c55f0ce576
- < 41e06fcc5df0774d212e70c5b503fc769492bce3
- < 8b17adf6d4fb6bf61fa4c3f58366a7c082799a71
- < f193e38cb257d033060b63f1cfd94af076b3a2ab
- < d00c953a8f69921f484b629801766da68f27f658
- 4.14
Fixed versions
- 5.10.260
- 5.15.211
- 6.1.177
- 6.6.144
- 6.12.95
- 6.18.37
- 7.0.14
- 7.1
How to fix it
CVE-2026-64188 affects Linux and involves memory-safety failure. A crafted input may corrupt memory, crash the process, or enable code execution in the affected context. Prioritize deployments that process untrusted input, expose the affected feature, or hold sensitive data. Upgrade Linux to 5.10.260, 5.15.211, 6.1.177, 6.6.144, 6.12.95, 6.18.37, 7.0.14, 7.1 or a later vendor-supported fixed release.
- Inventory every deployment, device, package, plugin, container, build, and environment that uses Linux.
- Compare the installed version with the recorded affected range: < c4e676c3505c5058922dc1a6f1ded795f6758135, < 9918698cf3aee4032e12bb42fd5a951dc465339b, < 310b93246bfec7d4452507e0c15477377ed9f025, < 1078ae8175777e80c9637996fb4a46c55f0ce576, < 41e06fcc5df0774d212e70c5b503fc769492bce3, < 8b17adf6d4fb6bf61fa4c3f58366a7c082799a71.
- Upgrade Linux to 5.10.260, 5.15.211, 6.1.177, 6.6.144, 6.12.95, 6.18.37, 7.0.14, 7.1 or a later vendor-supported fixed release.
- Until patched, limit untrusted files and peers, apply resource limits, and isolate the affected parser or service.
- Review configuration, roles, tokens, network paths, and exposed endpoints connected to Linux; remove access that is not required.
- Review application, system, proxy, and audit logs for requests and behavior linked to the affected feature and CVE.
- If exploitation is suspected, isolate affected assets, preserve evidence, rotate exposed credentials or keys, restore trusted data, and rebuild compromised systems before returning them to service.
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Verify the fix
- Confirm every affected asset now runs the fixed vendor-supported release or has the documented mitigation for CVE-2026-64188 in place.
- Use a safe regression test to confirm the affected memory-safety failure path no longer produces the vulnerable behavior.
- Confirm temporary access controls, endpoint restrictions, network blocks, and least-privilege settings remain effective after the update.
- Review post-remediation logs and rerun Fixnx plus the relevant package, dependency, firmware, browser, or product-specific security check.
- Document affected assets, versions, changes, validation evidence, reviewed logs, and any credential rotation, cleanup, or replacement completed.
Related categories
Related security risks
More published guidance from the same primary category.
Trusted references
FAQ
What is affected by CVE-2026-64188?
Linux versions listed as affected should be reviewed: < c4e676c3505c5058922dc1a6f1ded795f6758135, < 9918698cf3aee4032e12bb42fd5a951dc465339b, < 310b93246bfec7d4452507e0c15477377ed9f025, < 1078ae8175777e80c9637996fb4a46c55f0ce576, < 41e06fcc5df0774d212e70c5b503fc769492bce3, < 8b17adf6d4fb6bf61fa4c3f58366a7c082799a71, < f193e38cb257d033060b63f1cfd94af076b3a2ab, < d00c953a8f69921f484b629801766da68f27f658, 4.14.
What should I fix first?
Start with internet-facing sites, admin panels, login flows, plugins, themes, modules, packages, and systems that process user-controlled input or sensitive data.
How do I confirm the fix worked?
Apply the patched version or mitigation, clear caches where relevant, retest the affected workflow, and run a new Fixnx scan to verify public website exposure signals.
How are Fixnx security risk categories chosen?
Fixnx keeps one canonical risk page and assigns only broad, relevant categories such as ecosystem, technology area, or vulnerability class.