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CVE-2026-90104: NFSv4.1: zero referring call lists before decoding

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-17 · updated 2026-10-30

Description

In the Linux kernel, the following vulnerability has been resolved: NFSv4.1: zero referring call lists before decoding decode_cb_sequence_args() allocates csa_rclists with kmalloc_objs(), so each referring_call_list starts uninitialized. decode_rc_list() assigns rcl_refcalls only when rcl_nrefcalls is nonzero. A valid list with zero referring calls therefore leaves the pointer uninitialized, and nfs4_callback_sequence() later passes stale slab contents to kfree(). Allocate csa_rclists with kzalloc_objs() so every rcl_refcalls member is NULL from the beginning, including valid empty referring call lists.

Affected products

• Linux: 2.6.31 — fixed in 7.3

How to fix

Upgrade to a fixed version: Linux 7.3. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/7510a5b9edec9d9536a4e69f10edfb2592e6cf7f
• https://git.kernel.org/stable/c/810f6b3a29ac96fdc16909132b31627dae6824c2
• https://git.kernel.org/stable/c/8fa4804fe62ca4155a2d8fc2789d630376cbf2fc
• https://git.kernel.org/stable/c/ed54460caf5b5aa65ec03c9a6032d831f39f19f5
• https://git.kernel.org/stable/c/f31f3c042e024aef437cda42f0424ae8d4594b6c
• https://git.kernel.org/stable/c/f4d23937e1c41995c2f54af26c89b5e48a41c299

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