Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: ipv4: fib: bound automatic table ID allocation fib_empty_table() probes every table ID from 1 until it finds a free one. IPv4 tables are stored in a 256-bucket hash table, so a dense set of IDs makes each probe walk a growing hash chain while RTNL is held. Automatic table assignment ("ip rule ... table 0") is an IPv4-only legacy path. Bound the automatically allocated ID to 4096 so the RTNL hold stays bounded, without changing lookups of explicitly specified table IDs. This changes user-visible behavior. A table-0 rule previously received the lowest free ID in 1..RT_TABLE_MAX (0xFFFFFFFF). After this patch the search stops at 4096 and the rule add fails with ENOBUFS if that range is fully occupied. Explicit table IDs above 4096 remain usable. The automatic path is unused in practice: it is IPv4-only, not documented by ip-rule, uncovered by kernel selftests, and both NetworkManager and systemd refuse table 0.
References
- https://git.kernel.org/stable/c/125890702ef4417cd0ffac2e448c0cd4fbf0ac45
- https://git.kernel.org/stable/c/2c29c053a6627dc4f12fcfe6b4860bcd9e5d7503
- https://git.kernel.org/stable/c/3080f9e653d8c057d5652db5ced8137f81b3fcbd
- https://git.kernel.org/stable/c/999bc00588cb305ab25065e8a8ac31da7465301c
- https://git.kernel.org/stable/c/bc8d01d856db106f284b19961af6112e10c3e3b4
- https://git.kernel.org/stable/c/efdfb1e27a3328085b79540dfe781d537b576ea1
- https://git.kernel.org/stable/c/f1f2da33eaab54b4d5cdea6d70befb2e2fb49cb6
- https://git.kernel.org/stable/c/fe9a906d2bff2d2707bafd6353b5e032a42aeb35
FAQ
What is CVE-2026-97598?
CVE-2026-97598 is a documented vulnerability. In the Linux kernel, the following vulnerability has been resolved: ipv4: fib: bound automatic table ID allocation fib_empty_table() probes every table ID from 1 until it finds a free one. IPv4 tab...
How severe is CVE-2026-97598?
CVSS scoring is not yet available for CVE-2026-97598. Check NVD for updates.
Is there a patch for CVE-2026-97598?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.