CVE-2025-38089: linux kernel Null Dereference — Exploit

Description

In the Linux kernel, the following vulnerability has been resolved: sunrpc: handle SVC_GARBAGE during svc auth processing as auth error tianshuo han reported a remotely-triggerable crash if the client sends a kernel RPC server a specially crafted packet. If decoding the RPC reply fails in such a way that SVC_GARBAGE is returned without setting the rq_accept_statp pointer, then that pointer can be dereferenced and a value stored there. If it's the first time the thread has processed an RPC, then that pointer will be set to NULL and the kernel will crash. In other cases, it could create a memory scribble. The server sunrpc code treats a SVC_GARBAGE return from svc_authenticate or pg_authenticate as if it should send a GARBAGE_ARGS reply. RFC 5531 says that if authentication fails that the RPC should be rejected instead with a status of AUTH_ERR. Handle a SVC_GARBAGE return as an AUTH_ERROR, with a reason of AUTH_BADCRED instead of returning GARBAGE_ARGS in that case. This sidesteps the whole problem of touching the rpc_accept_statp pointer in this situation and avoids the crash.

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CVSS v3.1 Score

5.5

MEDIUM

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

Weakness Type (CWE)

CWE-476 CWE-476

Affected Products

Vendor	Product	Versions
linux	linux_kernel	6.3.4 — 6.4
linux	linux_kernel	6.4.1 — 6.6.95
linux	linux_kernel	6.7 — 6.12.35
linux	linux_kernel	6.13 — 6.15.4
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All

References

Advisories & Patches

https://git.kernel.org/stable/c/353e75b55e583635bf71cde6abcec274dba05edd https://git.kernel.org/stable/c/599c489eea793821232a2f69a00fa57d82b0ac98 https://git.kernel.org/stable/c/94d10a4dba0bc482f2b01e39f06d5513d0f75742 https://git.kernel.org/stable/c/c90459cd58bb421d275337093d8e901e0ba748dd https://github.com/keymaker-arch/NFSundown

Exploits

https://github.com/keymaker-arch/NFSundown

Other References

https://www.openwall.com/lists/oss-security/2025/07/02/2 http://www.openwall.com/lists/oss-security/2025/07/02/2

Frequently Asked Questions

What is CVE-2025-38089? +

In the Linux kernel, the following vulnerability has been resolved: sunrpc: handle SVC_GARBAGE during svc auth processing as auth error tianshuo han reported a remotely-triggerable crash if the client sends a kernel RPC server a specially crafted packet. If decoding the RPC reply fails in such a way that SVC_GARBAGE is returned without setting the rq_accept_statp pointer, then that pointer can be dereferenced and a value stored there. If it's the first time the thread has processed an RPC, then that pointer will be set to NULL and the kernel will crash. In other cases, it could create a memory scribble. The server sunrpc code treats a SVC_GARBAGE return from svc_authenticate or pg_authenticate as if it should send a GARBAGE_ARGS reply. RFC 5531 says that if authentication fails that the RPC should be rejected instead with a status of AUTH_ERR. Handle a SVC_GARBAGE return as an AUTH_ERROR, with a reason of AUTH_BADCRED instead of returning GARBAGE_ARGS in that case. This sidesteps the whole problem of touching the rpc_accept_statp pointer in this situation and avoids the crash. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2025-38089? +

CVE-2025-38089 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2025-38089? +

CVE-2025-38089 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-38089? +

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.

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