CVE-2025-68795
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2026-01-13

Last updated on: 2026-01-19

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: ethtool: Avoid overflowing userspace buffer on stats query The ethtool -S command operates across three ioctl calls: ETHTOOL_GSSET_INFO for the size, ETHTOOL_GSTRINGS for the names, and ETHTOOL_GSTATS for the values. If the number of stats changes between these calls (e.g., due to device reconfiguration), userspace's buffer allocation will be incorrect, potentially leading to buffer overflow. Drivers are generally expected to maintain stable stat counts, but some drivers (e.g., mlx5, bnx2x, bna, ksz884x) use dynamic counters, making this scenario possible. Some drivers try to handle this internally: - bnad_get_ethtool_stats() returns early in case stats.n_stats is not equal to the driver's stats count. - micrel/ksz884x also makes sure not to write anything beyond stats.n_stats and overflow the buffer. However, both use stats.n_stats which is already assigned with the value returned from get_sset_count(), hence won't solve the issue described here. Change ethtool_get_strings(), ethtool_get_stats(), ethtool_get_phy_stats() to not return anything in case of a mismatch between userspace's size and get_sset_size(), to prevent buffer overflow. The returned n_stats value will be equal to zero, to reflect that nothing has been returned. This could result in one of two cases when using upstream ethtool, depending on when the size change is detected: 1. When detected in ethtool_get_strings(): # ethtool -S eth2 no stats available 2. When detected in get stats, all stats will be reported as zero. Both cases are presumably transient, and a subsequent ethtool call should succeed. Other than the overflow avoidance, these two cases are very evident (no output/cleared stats), which is arguably better than presenting incorrect/shifted stats. I also considered returning an error instead of a "silent" response, but that seems more destructive towards userspace apps. Notes: - This patch does not claim to fix the inherent race, it only makes sure that we do not overflow the userspace buffer, and makes for a more predictable behavior. - RTNL lock is held during each ioctl, the race window exists between the separate ioctl calls when the lock is released. - Userspace ethtool always fills stats.n_stats, but it is likely that these stats ioctls are implemented in other userspace applications which might not fill it. The added code checks that it's not zero, to prevent any regressions.
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Meta Information
Published
2026-01-13
Last Modified
2026-01-19
Generated
2026-05-07
AI Q&A
2026-01-14
EPSS Evaluated
2026-05-05
NVD
CVE-2025-68795
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
linux ethtool *
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-UNKNOWN
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability occurs in the Linux kernel's ethtool utility when the number of network statistics changes between multiple ioctl calls used to query stats. Because ethtool uses three separate ioctl calls to get the size, names, and values of stats, if the stats count changes (due to device reconfiguration or dynamic counters in some drivers), the userspace buffer allocated may be incorrect, leading to a potential buffer overflow. The fix prevents this overflow by returning no data if a mismatch in expected sizes is detected, avoiding incorrect or shifted stats and preventing memory corruption.


How can this vulnerability impact me? :

This vulnerability can lead to a buffer overflow in userspace when querying network statistics with ethtool, which may cause memory corruption or crashes in applications using ethtool. Although the patch prevents overflow and results in either no stats or zeroed stats being reported temporarily, the underlying race condition remains. This could affect the reliability and stability of network monitoring tools or other software relying on ethtool statistics.


How can this vulnerability be detected on my network or system? Can you suggest some commands?

This vulnerability can be detected by observing the behavior of the ethtool -S command on network interfaces. Specifically, if you run `ethtool -S <interface>` (e.g., `ethtool -S eth2`) and see either "no stats available" or all stats reported as zero, this may indicate the transient condition caused by the vulnerability. These cases occur when the number of stats changes between ioctl calls, leading to either no output or cleared stats.


What immediate steps should I take to mitigate this vulnerability?

Immediate mitigation involves updating to a Linux kernel version that includes the patch which prevents userspace buffer overflow by handling mismatches in stats size gracefully. Until then, monitoring for the described ethtool -S anomalies can help identify affected devices. There is no direct workaround mentioned; the patch ensures no buffer overflow occurs but does not fix the underlying race condition.


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