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CVE-2026-64015
security/keys: fix missed RCU read section on lookup
Published 2026-07-19 (3 months ago) by the Linux kernel CNA. Subsystem security/keys. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-64015 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 | fixed | 6.1.176-1 | Update the kernel and reboot. Fixed in 6.1.176-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.94-1 | Update the kernel and reboot. Fixed in 6.12.94-1. A running kernel keeps the old code until the machine restarts. |
| 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
Nicholas Carlini reports that the keyring code calls assoc_array_find() in find_key_to_update() without holding the RCU read lock, while the assoc_array_gc() code really is designed around removing the node from the tree and then freeing it after an RCU grace-period. The regular key handling doesn't see this because holding the keyring semaphore hides any lifetime issues, but the persistent key handling uses a different model. Instead of extending the keyring locking, just do the simple RCU locking that the assoc_array was designed for.
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.
security/keys/keyring.c
- What this is
- KEYS/KEYRINGSMAINTAINERS section matched on security/keys/ · keyrings@vger.kernel.org · Maintained
Check it on the machine
grep -w CONFIG_KEYS /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 below compiles the affected file into the kernels it ships.
- bookworm, trixie, forky, sidy
- y
- built into the kernel image on every flavour - only a patch removes it
- Build switch
- CONFIG_KEYS
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
- 0.20%, higher than 9.2% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- security/keys
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 3.13 | 6.1.175 | 4c5d407ba3ff |
| 3.13 | 6.6.142 | cefa4265b111 |
| 3.13 | 6.12.92 | 5659e6923cb7 |
| 3.13 | 6.18.34 | 50bb3435a5e6 |
| 3.13 | 7.0.11 | 66288dcadf80 |
| 3.13 | 7.1 | 43a1e3744548 |
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 find_key_to_update() on the persistent keyring register, which is invoked from keyctl_get_persistent() via the keyctl(2) syscall. There is no network, adjacent-radio, or physical-device path to this code.
- AC:LAttack complexity, low
- Exploitation is a race between assoc_array_find() and assoc_array_gc() on the .persistent_register keyring; the attacker controls both sides by repeatedly calling KEYCTL_GET_PERSISTENT (including from multiple threads) while driving key expiry/GC via keyctl timeouts or natural garbage collection. Per kernel guidance, attacker-controlled races are AC:L.
- PR:LPrivileges required, low
- Any unprivileged local user who can invoke keyctl() can call KEYCTL_GET_PERSISTENT for their own UID (-1) with a writable destination keyring (e.g., session keyring). No real-root or CAP_SETUID capability is required for the vulnerable lookup path; this remains PR:L even inside user namespaces.
- UI:NUser interaction, none
- Exploitation requires only the attacker's own keyctl syscalls and does not depend on any victim user action such as mounting a filesystem or opening a file.
- S:UScope, unchanged
- Impact is confined to kernel memory corruption and privilege escalation within the same kernel security domain; it does not cross a VM, container, or IOMMU boundary on its own.
- C:HConfidentiality impact, high
- assoc_array_find() is documented to require an RCU read lock, but the persistent-keyring path called it without one while assoc_array_gc() frees tree nodes via call_rcu(), yielding a use-after-free on assoc_array nodes/leaves. UAF on kernel heap objects can be turned into arbitrary kernel memory reads.
- I:HIntegrity impact, high
- The freed assoc_array nodes can be reallocated and corrupted through concurrent GC versus lookup, providing a standard kernel heap UAF primitive that can be developed into arbitrary write or code-execution primitives.
- A:HAvailability impact, high
- Dereferencing RCU-freed assoc_array tree nodes during lookup can cause kernel oops/panic from invalid pointer access, and UAF exploitation commonly destabilizes or crashes the kernel even when full exploitation is not attempted.