Heap overflow in FUSE_LISTXATTR
FreeBSD-SA-26:20.fusefs · CVE-2026-45252
Our decision for FreeSense
FreeBSD corrected this on 2026-05-20, before the FreeBSD source pin of every FreeSense version.
- Advisory: corrected 2026-05-20
- FreeSense 1.0 pin: e004ff15f87e (2026-08-03)
- FreeSense 1.1 pin: a52c50b4b7c2 (2026-10-04)
- FreeSense 1.2 pin: a52c50b4b7c2 (2026-10-04)
By FreeSense version
| Version | Status | FreeBSD pin |
|---|---|---|
| FreeSense 1.01.0.7 · frozen, no further fixes | FixedFreeBSD pin of 2026-08-03 | 2026-08-03e004ff15 |
| FreeSense 1.11.1.9 | FixedFreeBSD pin of 2026-10-04 | 2026-10-04a52c50b4 |
| FreeSense 1.21.2.0-DEVELOPMENT | FixedFreeBSD pin of 2026-10-04 | 2026-10-04a52c50b4 |
Workaround
No workaround is available, but systems that do not load the fusefs kernel module or set vfs.usermount=1 are unaffected.
What FreeBSD says
When a fusefs file system implements extended attributes, the kernel may send a FUSE_LISTXATTR message to the userspace daemon to retrieve the list of extended attributes for a given file. The FUSE protocol requires the daemon to return a packed list of NUL-terminated strings. The fusefs kernel module calls strlen() on this daemon-supplied buffer without first verifying that the entire list is NUL-terminated.
Impact
If a malicious daemon sends a non-NUL-terminated list, the fusefs kernel module may read beyond the end of one heap-allocated buffer and potentially write beyond the end of a second buffer. A malicious daemon could disclose up to 253 bytes of kernel heap memory, or it could inject up to 250 attacker-controlled bytes into unallocated kernel heap space.
Excerpt from the FreeBSD advisory. Read the original for the full text and the fix.