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CVE-2026-80531
xfs: avoid UAF on sc->tempip in xrep_tempfile_create
Published 2026-08-26 (2 months ago) by the Linux kernel CNA. Subsystem fs/xfs. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-80531 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| Debian 13trixie | fixed | 6.12.105-1 | Update the kernel and reboot. Fixed in 6.12.105-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.10-1 | Update the kernel and reboot. Fixed in 7.1.10-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.10-1 | Update the kernel and reboot. Fixed in 7.1.10-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4788-1 · 2026-09-19 · text | 6.12.107-1~deb12u1 | Update the kernel and reboot. DLA-4788-1 shipped the fix on 2026-09-19, in 6.12.107-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
LOLLM noticed a potential UAF if the tempfile creation code fails after it set sc->tempip. Fix that.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
fs/xfs/scrub/tempfile.c
- What this is
- XFS FILESYSTEMMAINTAINERS section matched on fs/xfs/ · linux-xfs@vger.kernel.org · Supported
Show whether Debian builds this, per release
Not established. This site could not find the build rule for the affected file in the kernel trees Debian ships, so it has no answer about whether Debian compiles this code. Read that as unknown, never as absent.
- bookworm, trixie, forky, sid, bookworm · linux-6.12?
- ?
- not established - no Makefile entry for the affected file
Where a release above reads "not established", no build rule for the affected file was found in that release's kernel tree. That is a gap in this lookup, not a finding that the code is absent.
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS
Signals
- Published
- 2026-08-26 (2 months ago)source
- CVSS
- 7.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.13%, higher than 2.2% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- fs/xfs
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.10 | 6.12.105 | 08a20776ce33 |
| 6.10 | 6.18.46 | cd1f876d1bc2 |
| 6.10 | 7.1.10 | 96246a3200d3 |
| 6.10 | 7.2 | 0c88e10d12de |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4788-1 | 2026-09-19 | bookworm 6.12.107-1~deb12u1 | tracker |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:LAttack vector, local
- The bug is only reachable via XFS_IOC_SCRUB_METADATA or XFS_IOC_SCRUBV_METADATA ioctl on an open XFS file descriptor (xfs_file_ioctl -> xfs_ioc_scrub_metadata -> xfs_scrub_metadata -> xrep_setup_* -> xrep_tempfile_create); it is not exposed through NFS, SMB, or other network-facing kernel services.
- AC:LAttack complexity, low
- An attacker with ioctl access can deterministically hit the error path by invoking online repair (XFS_SCRUB_IFLAG_REPAIR) and forcing tempfile creation to fail after xfs_icreate sets sc->tempip (e.g., ENOSPC from filling the filesystem or EIO), without races or uncontrollable victim state.
- PR:LPrivileges required, low
- Both scrub ioctl handlers enforce capable(CAP_SYS_ADMIN), which is obtainable by unprivileged users who map root in a user namespace and mount their own XFS filesystem to run online scrub/repair, consistent with other XFS scrub CVE scoring.
- UI:NUser interaction, none
- Exploitation requires no victim interaction; the attacker issues the scrub/repair ioctl themselves once they have the required privileges and can induce the tempfile-creation failure.
- S:UScope, unchanged
- Impact is kernel memory corruption and crash within the same kernel security domain during XFS online repair teardown; this does not cross VM, container, or IOMMU security boundaries.
- C:HConfidentiality impact, high
- On failure after sc->tempip is set, xrep_tempfile_create releases the inode but left a dangling pointer; xchk_teardown then calls xrep_tempfile_rele which performs xfs_is_metadir_inode, xfs_iunlock, and xchk_irele on freed xfs_inode memory—a use-after-free enabling arbitrary kernel read.
- I:HIntegrity impact, high
- The stale sc->tempip is dereferenced in xrep_tempfile_rele for locking, metadir cleanup, and inode release on freed memory; UAF on xfs_inode structures can corrupt heap metadata and be leveraged for arbitrary kernel write or control-flow hijacking.
- A:HAvailability impact, high
- Use-after-free on sc->tempip during xchk_teardown provokes double-free, invalid inode lock operations, or kernel oops/panic when online repair setup fails after partial tempfile creation, causing complete host denial of service.