CVE-2022-50747 hfs: Fix OOB Write in hfs_asc2mac
An out-of-bounds write in the Linux kernel HFS filesystem allows attackers to potentially execute code or escalate privileges via a crafted filesystem image.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2022-50747?
CVE-2022-50747 is a high-severity memory corruption vulnerability in Linux, published on 24 Dec 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
hfs: Fix OOB Write in hfs_asc2mac
Syzbot reported a OOB Write bug:
loop0: detected capacity change from 0 to 64 ================================================================== BUG: KASAN: slab-out-of-bounds in hfs_asc2mac+0x467/0x9a0 fs/hfs/trans.c:133 Write of size 1 at addr ffff88801848314e by task syz-executor391/3632
Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1b1/0x28e lib/dump_stack.c:106 print_address_description+0x74/0x340 mm/kasan/report.c:284 print_report+0x107/0x1f0 mm/kasan/report.c:395 kasan_report+0xcd/0x100 mm/kasan/report.c:495 hfs_asc2mac+0x467/0x9a0 fs/hfs/trans.c:133 hfs_cat_build_key+0x92/0x170 fs/hfs/catalog.c:28 hfs_lookup+0x1ab/0x2c0 fs/hfs/dir.c:31 lookup_open fs/namei.c:3391 [inline] open_last_lookups fs/namei.c:3481 [inline] path_openat+0x10e6/0x2df0 fs/namei.c:3710 do_filp_open+0x264/0x4f0 fs/namei.c:3740
If in->len is much larger than HFS_NAMELEN(31) which is the maximum length of an HFS filename, a OOB write could occur in hfs_asc2mac(). In that case, when the dst reaches the boundary, the srclen is still greater than 0, which causes a OOB write. Fix this by adding a check on dstlen in while() before writing to dst address.
Which versions are affected by CVE-2022-50747?
How do I fix CVE-2022-50747?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2022-50747 being exploited?
There is no known exploitation of CVE-2022-50747 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2022-50747, GHSA-6fwf-f783-hfqc, UBUNTU-CVE-2022-50747.