CVE-2026-63837 net: ena: PHC: Check return code before setting timestamp output
A local attacker can read uninitialized kernel memory via the ENA network driver's PTP ioctl interface due to missing error checks.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-63837?
CVE-2026-63837 is a vulnerability in Linux, published on 19 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
net: ena: PHC: Check return code before setting timestamp output
ena_phc_gettimex64() is setting the output parameter regardless of whether ena_com_phc_get_timestamp() succeeded or failed.
When ena_com_phc_get_timestamp() returns an error, the timestamp parameter may contain uninitialized stack memory (e.g., when PHC is disabled or in blocked state) or invalid hardware values. Passing these to userspace via the PTP ioctl is both a security issue (information leak) and a correctness bug.
Fix by checking the return code after releasing the lock and only setting the output timestamp on success.
Which versions are affected by CVE-2026-63837?
How do I fix CVE-2026-63837?
Apply the vendor's patch.
Is CVE-2026-63837 being exploited?
There is no known exploitation of CVE-2026-63837 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-63837, DEBIAN-CVE-2026-63837, GHSA-g7h6-fhch-mvgh, UBUNTU-CVE-2026-63837.