CVE Catalog

CVE-2025-40210

HighCVSS 7.5
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.33%

25th percentile - higher than 25% of all known CVEs

Summary

In the Linux kernel, the NFS server (NFSD) removed the limit on operations per NFSv4 COMPOUND request, allowing an attacker to specify an arbitrarily large operation count. This causes massive memory allocation (e.g., 1.2 TB) and system crash.

Risk Assessment

The organization risks a DoS attack via crafted NFSv4 COMPOUND requests, exhausting memory and crashing the NFS server.

Recommendation

Update the Linux kernel to a version containing the fix for CVE-2025-40210 (restoring the 200-operation limit).

Other vulnerabilities in Linux kernel

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Original NVD description (English source)

In the Linux kernel, the following vulnerability has been resolved: Revert "NFSD: Remove the cap on number of operations per NFSv4 COMPOUND" I've found that pynfs COMP6 now leaves the connection or lease in a strange state, which causes CLOSE9 to hang indefinitely. I've dug into it a little, but I haven't been able to root-cause it yet. However, I bisected to commit 48aab1606fa8 ("NFSD: Remove the cap on number of operations per NFSv4 COMPOUND"). Tianshuo Han also reports a potential vulnerability when decoding an NFSv4 COMPOUND. An attacker can place an arbitrarily large op count in the COMPOUND header, which results in: [ 51.410584] nfsd: vmalloc error: size 1209533382144, exceeds total pages, mode:0xdc0(GFP_KERNEL|__GFP_ZERO), nodemask=(null),cpuset=/,mems_allowed=0 when NFSD attempts to allocate the COMPOUND op array. Let's restore the operation-per-COMPOUND limit, but increased to 200 for now.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS