CVE-2025-40049
- Published: 2025-10-28T12:15:39.043
- Last modified: 1761747353
In the Linux kernel, the following vulnerability has been resolved:
Squashfs: fix uninit-value in squashfs_get_parent
Syzkaller reports a “KMSAN: uninit-value in squashfs_get_parent” bug.
This is caused by open_by_handle_at() being called with a file handle
containing an invalid parent inode number. In particular the inode number
is that of a symbolic link, rather than a directory.
Squashfs_get_parent() gets called with that symbolic link inode, and
accesses the parent member field.
unsigned int parent_ino = squashfs_i(inode)->parent;
Because non-directory inodes in Squashfs do not have a parent value, this
is uninitialised, and this causes an uninitialised value access.
The fix is to initialise parent with the invalid inode 0, which will cause
an EINVAL error to be returned.
Regular inodes used to share the parent field with the block_list_start
field. This is removed in this commit to enable the parent field to
contain the invalid inode number 0.
Related CVE by CWE
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How to fix CVE-2025-40049
Description: In the Linux kernel, the following vulnerability has been resolved: Squashfs: fix uninit-value in squashfs_get_parent Syzkaller reports a “KMSAN: uninit-value in squashfs_get_parent” bug. This is caused by open_by_handle_at() being called with a file handle containing an invalid parent inode number. In particular the inode number is that of a symbolic link, rather than a directory. […]
Exploit Difficulty: HARD
⏱️ Time to exploit: > 4 hours
🛠️ Required skills: Advanced security expertise
💰 Public exploits: Rare or not public
How to Fix:
- Check if you're running the affected product
- Update to the latest patched version
- If patching is not immediately possible: restrict network exposure, apply least-privilege access
- Test the fix in a staging environment first
- Review logs for signs of exploitation
- Monitor for IOCs (Indicators of Compromise)
- Enable automatic security updates
- Set up vulnerability monitoring
- Review and harden security configurations
Exploit Difficulty Assessment
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Detection Rules & IOCs
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No vendor/product data available.