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CVE-2026-80720
iomap: add a separate bio_set for iomap_split_ioend
Published 2026-08-28 (2 months ago) by the Linux kernel CNA. Subsystem fs/iomap. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-80720 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 | not affected | 6.12.113-1 | Nothing to do. trixie never shipped the vulnerable code. |
| Debian 14forky | fixed | 7.1.8-1 | Update the kernel and reboot. Fixed in 7.1.8-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.8-1 | Update the kernel and reboot. Fixed in 7.1.8-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
iomap_split_ioend can split bios that already come from iomap_ioend_bioset and thus deadlock when the bioset is exhausted. Add a separate bio_set to avoid this deadlock. Christian Brauner <brauner@kernel.org> says: Mark iomap_ioend_split_bioset static as it is only used in ioend.c, fixing the sparse warning reported by the kernel test robot.
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/iomap/ioend.c
- What this is
- FILESYSTEMS [IOMAP]MAINTAINERS section matched on fs/iomap/ · linux-xfs@vger.kernel.org · Supported
Check it on the machine
grep -wE 'CONFIG_BLOCK|CONFIG_FS_IOMAP' /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
Show whether Debian builds this, per release
Debian builds this code. Every release with an answer below compiles the affected file into the kernels it ships. The build rule could not be established for 2 releases, so nothing is claimed about those.
- bookworm, trixie?
- forky, sidy
- ?
- not established - no Makefile entry for the affected file
- y
- built into the kernel image on every flavour - only a patch removes it
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.
- Build switches
- CONFIG_BLOCK, CONFIG_FS_IOMAP
- Reads as
- all on means the file is compiled; any one off means it is not.
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 kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-08-28 (2 months ago)source
- CVSS
- 7.5 high
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.61%, higher than 48.1% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- fs/iomap
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.15 | 6.18.44 | cfc686a1174a |
| 6.15 | 7.1.8 | 4a869be56e9f |
| 6.15 | 7.2 | c679ce3be6cb |
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:NAttack vector, network
- On ZNS-backed XFS realtime volumes exported via nfsd/ksmbd, remote client write I/O reaches vfs_write()->xfs_zone_alloc_and_submit()->iomap_split_ioend() in the server kernel without local shell access.
- AC:LAttack complexity, low
- An attacker with write access can deterministically exhaust the 32-entry iomap_ioend_bioset via concurrent large zoned writes or direct I/O needing multiple bio_split allocations from the same pool; they control thread count and I/O size without uncontrollable races.
- PR:NPrivileges required, none
- Triggering requires only permission to write realtime files on an XFS zoned filesystem via local syscall or network NFS/SMB client write; no CAP_SYS_ADMIN, ioctl, or init-namespace root is needed beyond write access to exported storage.
- UI:NUser interaction, none
- The attacker triggers the deadlock with their own concurrent write or direct-I/O requests; no separate victim must mount media, open a file, or perform any interactive action beyond the attacker's own I/O.
- S:UScope, unchanged
- The bioset mempool deadlock freezes zoned XFS I/O within the same host kernel security authority; it does not cross a VM, IOMMU, or sandbox boundary.
- C:NConfidentiality impact, none
- This is a mempool self-deadlock with no memory corruption, out-of-bounds access, use-after-free, or information disclosure; bio_split failure returns -ENOMEM rather than leaking kernel data.
- I:NIntegrity impact, none
- The bug causes tasks to block indefinitely on mempool allocation but does not corrupt, modify, or overwrite file data or enable arbitrary writes or code execution.
- A:HAvailability impact, high
- When iomap_ioend_bioset is exhausted, bio_split blocks on mempool_alloc() while holders cannot release entries, deadlocking writeback workers and zoned submit paths and hanging all I/O on the affected XFS zoned filesystem.