High

Out-of-bounds write in Linux kernel iavf_get_ethtool_stats()

IdentifiersCVE-2026-31505CWE-787· Out-of-bounds Write

CVE-2026-31505 is an out-of-bounds write vulnerability in the Linux kernel iavf network driver, specifically in iavf_get_ethtool_stats(). The bug is caused by inconsistent use of queue-count fields across related ethtool handlers: iavf_get_sset_count() and iavf_get_stat_strings() size the statistics buffer using a queue count derived from real_num_tx_queues, while iavf_get_ethtool_stats() iterates using a different runtime-varying queue count such as num_active_queues. During concurrent channel reconfiguration and statistics retrieval, for example simultaneous execution of "ethtool -L" and "ethtool -S", these values can diverge. A documented race occurs when queue/channel counts are changed from 1 to 8: the stats buffer may be allocated for 1 queue while iavf_get_ethtool_stats() writes statistics for 8 queues, resulting in vmalloc out-of-bounds writes. The upstream fix standardizes all related functions on immutable num_tx_queues to eliminate the mismatch.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation can corrupt kernel memory via out-of-bounds writes from the ethtool statistics path. The demonstrated result is a KASAN-detected vmalloc out-of-bounds write in iavf_add_one_ethtool_stat(), which can lead to kernel crashes, memory corruption, and potentially compromise confidentiality, integrity, and availability depending on exploitability in the target environment. Available scoring in the provided content characterizes the issue as local, requiring low privileges and no user interaction.

Mitigation

If you can’t patch tonight, do this now.

Until patched kernels are deployed, reduce exposure by restricting local access to privileged networking administration interfaces and limiting who can invoke ethtool operations against affected iavf-backed interfaces. Avoid concurrent use of channel reconfiguration (for example, "ethtool -L") and statistics collection (for example, "ethtool -S") on affected systems, as that race condition is explicitly described as the trigger. These are temporary risk-reduction measures only; patching is the definitive fix.

Remediation

Patch, then assume compromise.

Apply a Linux kernel update that includes the upstream fix for CVE-2026-31505. The fix changes the iavf ethtool statistics-related functions to use immutable num_tx_queues consistently instead of runtime-changing queue counters such as real_num_tx_queues or num_active_queues. Vendor-provided kernel updates referenced in the content, including SUSE advisories, should be installed according to the platform lifecycle and package stream in use, followed by a reboot where required.

PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType

LinuxLinux Kerneloperating_system

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

4 sources tracked across advisories and community write-ups. News coverage will land here when it surfaces.

4 SOURCESView more in app

No news coverage yet. Advisories and community discussion only.

What this page doesn’t show

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Exposure mapping

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Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity

Community discussion across Reddit, Mastodon, and other social sources.

EXTERNAL REFERENCES

MITRE CVE

cve.org · CVE-2026-31505

NVD

nvd.nist.gov/vuln/detail/CVE-2026-31505

MITRE CWE · CWE-787

Out-of-bounds Write

Patch

git.kernel.org/stable/c/1f931dee5b726df1940348ec31614d64bac03aa6

Patch

git.kernel.org/stable/c/bb85741d2dc2be207353a412f51b83697fcbefcf

Patch

git.kernel.org/stable/c/fdf902bf86a80bf15792a1d20a67a5302498d7f1

Patch

git.kernel.org/stable/c/fecacfc95f195b99c71c579a472120d0b4ed65fa