Medium [CVE-2026-63837] Check return code before setting timestamp output
This medium-severity Red Hat Linux advisory covers CVE-2026-63837 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat package: kernel.
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Summary
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. A flaw was found in the Linux kernel's Elastic Network Adapter (ENA) driver.
The driver's Precision Time Protocol (PTP) Hardware Clock (PHC) support, specifically the `ena_phc_gettimex64()` function, fails to check the return code of an internal timestamp retrieval function. This oversight can lead to uninitialized or invalid memory being passed to userspace applications through the PTP ioctl, resulting in an information leak.
This vulnerability allows a local user to potentially gain access to sensitive system information. Red Hat severity: Moderate — CVSS 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).
Weakness: CWE-201. Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 9.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative. Check it before change work.
Official advisory · medium-confidence parse· fetched 7 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists. Confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 7 days ago·verify at source
Mitigation
The source record does not include mitigation steps. That does not mean no fix exists. Read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 7 days ago·verify at source
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