Quick answers
- Is CVE-2026-98921 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-98921 being exploited in the wild.
- How severe is CVE-2026-98921?
- Informational severity, published 23 October 2026.
- Which products and versions are affected?
- Linux kernel affected versions with CONFIG_OVERLAY_FS_DEBUG enabled.
- Is there a fix for CVE-2026-98921?
- Yes: fixed in Fixed in commit ae146bc1abdeb4607abf2975b858c053024e8ac1. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-98921 attacked?
- It is attacked with local access, in an operating system.
- Am I affected by CVE-2026-98921?
- Check whether you run Linux kernel at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
How to fix
- Fixed in: Fixed in commit ae146bc1abdeb4607abf2975b858c053024e8ac1
Technical details
The ovl_do_mkdir() function in overlayfs prints a dentry pointer after calling vfs_mkdir(), but vfs_mkdir() may free or replace that dentry on failure or success. The debug print accesses freed memory, triggering a use-after-free when CONFIG_OVERLAY_FS_DEBUG is enabled. The fix moves the dentry print before the vfs_mkdir() call.
Affected products
- Linux kernel affected versions with CONFIG_OVERLAY_FS_DEBUG enabled
Timeline
- 2026-10-23: disclosed: Published as CVE-2026-98921
- 2026-09-25: patched