CVE-2026-31694

Summary

In the Linux kernel, the following vulnerability has been resolved: fuse: reject oversized dirents in page cache fuse_add_dirent_to_cache() computes a serialized dirent size from the server-controlled namelen field and copies the dirent into a single page-cache page. The existing logic only checks whether the dirent fits in the remaining space of the current page and advances to a fresh page if not. It never checks whether the dirent itself exceeds PAGE_SIZE. As a result, a malicious FUSE server can return a dirent with namelen=4095, producing a serialized record size of 4120 bytes. On 4 KiB page systems this causes memcpy() to overflow the cache page by 24 bytes into the following kernel page. Reject dirents that cannot fit in a single page before copying them into the readdir cache.

• CVE-2026-31694-POCExploit

  Linux kernel FUSE readdir cache out-of-bounds write (CVE-2026-31694): a malicious FUSE server overflows a page-cache page by 24 bytes. PoC plus an unprivileged local-root exploit via /etc/passwd page-cache corruption. Run only inside a VM.