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CVE-2026-52971
net: ena: PHC: Fix potential use-after-free in get_timestamp
Published 2026-06-24 (4 months ago) by the Linux kernel CNA. Subsystem drivers/net. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-52971 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 | 7.0.10-1 | Update the kernel and reboot. Fixed in 7.0.10-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.10-1 | Update the kernel and reboot. Fixed in 7.0.10-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
Move the phc->active check and resp pointer assignment to after acquiring the spinlock. Previously, phc->active was checked without holding the lock, and resp was cached from ena_dev->phc.virt_addr before the lock was acquired. If ena_com_phc_destroy() runs between the lockless active check and the lock acquisition, it sets active=false, releases the lock, frees the DMA memory, and sets virt_addr=NULL. The get_timestamp path would then read a NULL virt_addr and dereference it. With both the active check and the pointer read under the lock, destroy cannot free the memory while get_timestamp is using it.
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.
drivers/net/ethernet/amazon/ena/ena_com.c
- What this is
- AMAZON ETHERNET DRIVERSMAINTAINERS section matched on drivers/net/ethernet/amazon/ · netdev@vger.kernel.org · Maintained
- Kernel module
- ena
Check it on the machine
grep -wE 'CONFIG_ENA_ETHERNET|CONFIG_ETHERNET|CONFIG_NET_VENDOR_AMAZON' /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.
lsmod | grep -w enaPrints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian builds this, but not on every flavour. At least one release below builds the code on some of its kernel flavours and not on others, so the answer depends on the architecture and flavour installed.
- bookwormm
- trixieMnot built on armel/rpi, s390x/s390x
- forky, sidMnot built on s390x/s390x
- m
- a loadable module on every flavour - check lsmod, can be blacklisted
- M
- a module where it is built at all; some flavours do not build it
- Build switches
- CONFIG_ENA_ETHERNET, CONFIG_ETHERNET, CONFIG_NET_VENDOR_AMAZON
- 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
- 2026-06-24 (4 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 2.5% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- drivers/net
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.17 | 6.18.33 | 95e8ae9af2a6 |
| 6.17 | 7.0.10 | ca9ed40f2894 |
| 6.17 | 7.1 | e42c755582f0 |
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 vulnerable ENA PHC timestamp path is reached through local PTP clock access such as opening `/dev/ptpN` and invoking `clock_gettime()`/PTP ioctls, not by remote network packets.
- AC:LAttack complexity, low
- The bug is a retryable race between timestamp retrieval and ENA PHC destroy during reset/reinit, and repeated local timestamp calls can exercise the vulnerable window without special memory layout assumptions.
- PR:LPrivileges required, low
- The generic PTP gettime path has no capability check; the attacker only needs local access to the PTP character device/file descriptor, which is a low-privilege local access condition.
- UI:NUser interaction, none
- No victim action is required once the attacker can access the local PTP clock interface and race it with reset/destruction activity.
- S:UScope, unchanged
- The vulnerability affects kernel memory within the same host kernel security authority and does not cross a VM, IOMMU, or sandbox boundary.
- C:HConfidentiality impact, high
- This is a use-after-free of a coherent DMA response buffer whose contents are read back through timestamp retrieval, and under the required higher-severity rule UAF is treated as capable of high confidentiality impact.
- I:HIntegrity impact, high
- The stale response pointer is written through after free (`req_id` update) and may corrupt reused kernel/DMA memory, so under the UAF guidance this supports high integrity impact.
- A:HAvailability impact, high
- The stale or NULL/freed pointer dereference can oops or panic the kernel during timestamp retrieval, causing high availability impact.