Overview

In the Linux kernel, the following vulnerability has been resolved:

neighbour: Enforce min/max to NDTPA_INTERVAL_PROBE_TIME_MS.

NDTPA_INTERVAL_PROBE_TIME_MS sets .type and .min but misses .validation_type, so no validation is applied:

ynl --family rt-neigh --do setneightbl \

--json '{"name": "arp_cache", "parms": {"interval-probe-time-ms": 0}}'

ynl --family rt-neigh --dump getneightbl --output-json | \

jq '.[] | select(.name == "arp_cache" and has("config")) | .parms["interval-probe-time-ms"]' 0

Moreover, nla_get_msecs() uses msecs_to_jiffies(), and u64 is silently cast to u32, so a larger value can bypass the min check:

e.g. 4294967296 == 0x100000000

ynl --family rt-neigh --do setneightbl \

--json '{"name": "arp_cache", "parms": {"interval-probe-time-ms": 4294967296}}'

ynl --family rt-neigh --dump getneightbl --output-json | \

jq '.[] | select(.name == "arp_cache" and has("config")) | .parms["interval-probe-time-ms"]' 0

msecs_to_jiffies() returns MAX_JIFFY_OFFSET if the value is larger than INT_MAX. Also, INT_MAX ms overflows int NEIGH_VAR() when HZ > 1000 (Alpha, MIPS), and passing a negative integer to queue_delayed_work(unsigned long delay) causes sign extension, which wraps around the expiry time to the past, resulting in it being handled as 0 delay in the timer wheel.

Let's use NLA_POLICY_FULL_RANGE() and limit the max to 1 day.

The same max check is applied to sysctl as well.

Note that this controls the probe interval for NTF_MANAGED entries, so the max of 1 day is unlikely to break any deployments.

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

Vendor advisories

• Red Hat VEX · Low · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 10 · updated 2026-10-18 · vex