CVE-2026-23359

CVE-2026-23359 is a high-severity vulnerability in Linux Linux Kernel with a CVSS 3.x base score of 7.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-787.

Key facts

Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix stack-out-of-bounds write in devmap get_upper_ifindexes() iterates over all upper devices and writes their indices into an array without checking bounds. Also the callers assume that the max number of upper devices is MAX_NEST_DEV and allocate excluded_devices[1+MAX_NEST_DEV] on the stack, but that assumption is not correct and the number of upper devices could be larger than MAX_NEST_DEV (e.g., many macvlans), causing a stack-out-of-bounds write. Add a max parameter to get_upper_ifindexes() to avoid the issue. When there are too many upper devices, return -EOVERFLOW and abort the redirect. To reproduce, create more than MAX_NEST_DEV(8) macvlans on a device with an XDP program attached using BPF_F_BROADCAST | BPF_F_EXCLUDE_INGRESS. Then send a packet to the device to trigger the XDP redirect path.

Frequently asked questions

What is CVE-2026-23359?
In the Linux kernel, the following vulnerability has been resolved: bpf: Fix stack-out-of-bounds write in devmap get_upper_ifindexes() iterates over all upper devices and writes their indices into an array without checking bounds. Also the callers assume that the max number of upper devices is MAX_NEST_DEV and allocate excluded_devices[1+MAX_NEST_DEV] on the stack, but that assumption is not correct and the number of upper devices could be larger than MAX_NEST_DEV (e.g., many macvlans), causing a stack-out-of-bounds write. Add a max parameter to get_upper_ifindexes() to avoid the issue. When there are too many upper devices, return -EOVERFLOW and abort the redirect. To reproduce, create more than MAX_NEST_DEV(8) macvlans on a device with an XDP program attached using BPF_F_BROADCAST | BPF_F_EXCLUDE_INGRESS. Then send a packet to the device to trigger the XDP redirect path.
How severe is CVE-2026-23359?
CVE-2026-23359 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-23359 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (3rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-23359?
CVE-2026-23359 primarily affects Linux Linux Kernel. In total, 9 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-23359?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-23359 have an EU (EUVD) identifier?
Yes. CVE-2026-23359 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-15336.
When was CVE-2026-23359 published?
CVE-2026-23359 was published on 2026-03-25 and last updated on 2026-06-17.

References

Affected products (9)

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