Look up another CVE · open CVE-2026-63911 in the interactive tracker
CVE-2026-63911
xfrm: iptfs: reset runtime state when cloning SAs
Published 2026-07-19 (3 months ago) by the Linux kernel CNA. Subsystem net/xfrm. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-63911 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 | 7.0.12-1 | Update the kernel and reboot. Fixed in 7.0.12-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.12-1 | Update the kernel and reboot. Fixed in 7.0.12-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
iptfs_clone_state() clones the IPTFS mode data with kmemdup(). This copies runtime objects which must not be shared with the original SA, including the embedded sk_buff_head, hrtimers, spinlock, and in-flight reassembly/reorder state. If xfrm_state_migrate() fails after clone_state() but before the later init_state() call has reinitialized those fields, the cloned state can be destroyed by xfrm_state_gc_task() with list and timer state copied from the original SA. With queued packets this lets the clone splice and free skbs owned by the original IPTFS queue, leading to use-after-free and double-free reports in iptfs_destroy_state() and skb release paths. Reinitialize the clone's runtime state before publishing it through x->mode_data. Because clone_state() now publishes a destroyable mode_data object before init_state(), take the mode callback module reference there. Avoid taking it again from __iptfs_init_state() for the same object.
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.
net/xfrm/xfrm_iptfs.c
- What this is
- NETWORKING [IPSEC]MAINTAINERS section matched on net/xfrm/ · netdev@vger.kernel.org · Maintained
Check it on the machine
grep -wE 'CONFIG_XFRM|CONFIG_XFRM_IPTFS' /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 does not build this code in 2 releases. The build rule could not be established for 2 releases, so nothing is claimed about those.
- bookworm, trixie?
- forky, sidn
- ?
- not established - no Makefile entry for the affected file
- n
- not enabled on any flavour - this release does not build the code
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_XFRM, CONFIG_XFRM_IPTFS
- 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
- 2026-07-19 (3 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
- 0.17%, higher than 5.8% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- net/xfrm
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.14 | 6.18.35 | 9327252e0462 |
| 6.14 | 7.0.12 | dfb9f6cbfa98 |
| 6.14 | 7.1 | 7f83d1740732 |
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 reached only through local XFRM SA migration via netlink XFRM_MSG_MIGRATE or PF_KEY SADB_X_MIGRATE, not by processing remote network packets alone.
- AC:LAttack complexity, low
- On systems with IPTFS and XFRM_MIGRATE enabled, an attacker who controls the migrate request can reliably queue skbs on the SA and force a post-clone migration failure to trigger the shared-queue teardown.
- PR:LPrivileges required, low
- All XFRM migrate operations require CAP_NET_ADMIN on the target network namespace, which unprivileged users can obtain inside a user namespace via unshare.
- UI:NUser interaction, none
- Exploitation requires no victim interaction beyond the attacker’s own netlink/PF_KEY operations and traffic through an SA they control.
- S:UScope, unchanged
- Impact is kernel memory corruption and privilege escalation within the same kernel security authority, not a cross-VM or cross-IOMMU boundary escape.
- C:HConfidentiality impact, high
- The bug is a use-after-free on sk_buff objects where the clone’s destroy path frees skbs still owned by the live original IPTFS queue, enabling arbitrary kernel memory read primitives.
- I:HIntegrity impact, high
- Shared queue/timer state corruption and skb double-free provide exploitable heap corruption that can be leveraged for arbitrary kernel writes or code execution.
- A:HAvailability impact, high
- The vulnerability causes kernel oops/panic from UAF and double-free in skb release paths, and can be used for repeatable denial of service against the host.