CVE Catalog

CVE-2026-64264

MediumCVSS 5.5
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.15%

5th percentile - higher than 5% of all known CVEs

Summary

In the Linux kernel fuse-uring subsystem, a vulnerability exists where the EFAULT error is overwritten. After a copy_from_user() failure, fuse_uring_commit() sets err to a positive residual, causing fuse_uring_req_end() to overwrite -EFAULT with a positive value, masking the error.

Risk Assessment

An attacker could send a crafted request that is incorrectly treated as valid, leading to undefined behavior or data leakage.

Recommendation

Apply the Linux kernel patch that assigns err = -EFAULT before jumping to the out label in fuse_uring_commit().

Other vulnerabilities in Linux kernel

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Original NVD description (English source)

In the Linux kernel, the following vulnerability has been resolved: fuse-uring: fix EFAULT clobber in fuse_uring_commit copy_from_user() returns the number of bytes not copied as an unsigned residual on failure (1..sizeof(struct fuse_out_header)). fuse_uring_commit stores that residual in ssize_t err, sets req->out.h.error to -EFAULT, then jumps to out: with err still holding the positive residual. err = copy_from_user(&req->out.h, &ent->headers->in_out, sizeof(req->out.h)); if (err) { req->out.h.error = -EFAULT; goto out; /* err is the positive residual */ } ... out: fuse_uring_req_end(ent, req, err); fuse_uring_req_end() then runs if (error) req->out.h.error = error; which overwrites the just-assigned -EFAULT with the positive residual. FUSE callers such as fuse_simple_request() test err < 0 to detect failure, so the positive value is interpreted as success and the caller proceeds with an uninitialised or partial req->out.args. Fix by assigning err = -EFAULT in the failure branch before jumping to out, so fuse_uring_req_end() receives a negative errno and sets req->out.h.error to -EFAULT.

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