CVE-2025-39835 xfs: do not propagate ENODATA disk errors into xattr code
A null pointer dereference in the Linux kernel XFS filesystem can cause a system crash when disk errors are misinterpreted as missing attributes.
- 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-2025-39835?
CVE-2025-39835 is a high-severity vulnerability in Debian Debian Linux, published on 16 Sep 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:
xfs: do not propagate ENODATA disk errors into xattr code
ENODATA (aka ENOATTR) has a very specific meaning in the xfs xattr code; namely, that the requested attribute name could not be found.
However, a medium error from disk may also return ENODATA. At best, this medium error may escape to userspace as "attribute not found" when in fact it's an IO (disk) error.
At worst, we may oops in xfs_attr_leaf_get() when we do:
error = xfs_attr_leaf_hasname(args, &bp); if (error == -ENOATTR) { xfs_trans_brelse(args->trans, bp); return error; }
because an ENODATA/ENOATTR error from disk leaves us with a null bp, and the xfs_trans_brelse will then null-deref it.
As discussed on the list, we really need to modify the lower level IO functions to trap all disk errors and ensure that we don't let unique errors like this leak up into higher xfs functions - many like this should be remapped to EIO.
However, this patch directly addresses a reported bug in the xattr code, and should be safe to backport to stable kernels. A larger-scope patch to handle more unique errors at lower levels can follow later.
(Note, prior to 07120f1abdff we did not oops, but we did return the wrong error code to userspace.)
Which versions are affected by CVE-2025-39835?
It affects 2 products.
Products include Debian Debian Linux, Linux kernel.
How do I fix CVE-2025-39835?
Apply the vendor's patch.
Is CVE-2025-39835 being exploited?
There is no known exploitation of CVE-2025-39835 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as AZL-74736, BELL-CVE-2025-39835, DEBIAN-CVE-2025-39835, GHSA-x6rc-wf46-fv7m, ROOT-OS-DEBIAN-11-CVE-2025-39835, ROOT-OS-UBUNTU-2204-CVE-2025-39835 and 2 more.