CVE-2026-90131 — Linux kernel
CVE-2026-90131 is a security vulnerability. No vendor fix is recorded yet; mitigation options are listed below.
In the Linux kernel, the following vulnerability has been resolved: ntfs: serialize resident iomap reads with mrec_lock ntfs_read_iomap_begin_resident() walks the MFT record through ntfs_attr_lookup()…
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Description
In the Linux kernel, the following vulnerability has been resolved:
ntfs: serialize resident iomap reads with mrec_lock
ntfs_read_iomap_begin_resident() walks the MFT record through ntfs_attr_lookup() -> ntfs_attr_find() without taking ni->mrec_lock, while ntfs_attr_record_resize(), ntfs_make_room_for_attr() and ntfs_resident_attr_record_add() memmove() the same base_ni->mrec buffer under that lock. map_mft_record() only takes a reference and does not serialize, so the reader can observe torn attribute length and offset fields while a writer is relocating the records.
KCSAN reports the race between the mmap read fault path and both link() and unlink():
BUG: KCSAN: data-race in ntfs_attr_find / ntfs_attr_record_resize
write to 0xffff888100af1018 of 4 bytes by task 96 on cpu 1: ntfs_attr_record_resize+0xd2/0x130 ntfs_attr_record_rm+0xad/0x530 ntfs_delete+0x224/0x640 ntfs_unlink+0x14d/0x280 vfs_unlink+0x157/0x520
read to 0xffff888100af1018 of 4 bytes by task 95 on cpu 0: ntfs_attr_find+0x104/0x5b0 ntfs_attr_lookup+0x39c/0x10c0 ntfs_read_iomap_begin_resident+0xc6/0x230 ntfs_read_iomap_begin+0x5d/0xa0 iomap_iter+0x2e2/0x6e0 iomap_read_folio+0x147/0x2a0 ntfs_read_folio+0x108/0x170 filemap_read_folio+0x35/0x100 filemap_fault+0x993/0x1000
value changed: 0x00000250 -> 0x000001f0
The address is mrec + 0x18, i.e. mft_record.bytes_in_use, and the change is the 96 bytes of one $FILE_NAME attribute being removed.
Keep base_ni->mrec_lock from the resident read iomap lookup through iomap_end(). This protects both the attribute walk and the subsequent copy from iomap->inline_data, which points into the MFT record. The non-resident path is left alone: ntfs_lookup() already holds the directory inode's mrec_lock when it reads an index folio through read_mapping_folio(), and taking the lock in the shared wrapper deadlocks there with recursive locking on mrec_lock. The comment above the read_mapping_folio() call in fs/ntfs/dir.c notes the same hazard.
The seek path uses the same lookup helper but does not dereference iomap->inline_data. Release the lock before returning from that path, whereas the regular read path records base_ni in iomap->private and releases the lock from its iomap_end() callback.
Tested with a reproducer that faults in a 16-byte resident file while another thread runs link()/unlink() on it. Before: 40 KCSAN reports in about one second. After: no reports in 180 seconds over 206,090 read iterations and 423,540 link/unlink cycles. A PROVE_LOCKING build shows no lockdep splat with the same reproducer running for 60 seconds.
Detection & mitigation playbook
VulnerabilityDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for the affected component, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Remediation status
No patched version of the affected component has shipped for CVE-2026-90131 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-90131 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-90131. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-90131 in your dependencies?
O3 Security finds CVE-2026-90131 across dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.