CVE-2026-97598

ipv4: fib: bound automatic table ID allocation

State: Published
Severity: Not scored
Published: Sep 25, 2026
Updated: Oct 19, 2026
Reserved: Sep 24, 2026

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.

Scores

The record has no CVSS score.

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	b801f54917b7c6e8540f877ee562cd0725e62ebd to before 999bc00588cb305ab25065e8a8ac31da7465301cAffected b801f54917b7c6e8540f877ee562cd0725e62ebd to before f1f2da33eaab54b4d5cdea6d70befb2e2fb49cb6Affected b801f54917b7c6e8540f877ee562cd0725e62ebd to before 125890702ef4417cd0ffac2e448c0cd4fbf0ac45Affected b801f54917b7c6e8540f877ee562cd0725e62ebd to before 3080f9e653d8c057d5652db5ced8137f81b3fcbdAffected b801f54917b7c6e8540f877ee562cd0725e62ebd to before bc8d01d856db106f284b19961af6112e10c3e3b4Affected b801f54917b7c6e8540f877ee562cd0725e62ebd to before fe9a906d2bff2d2707bafd6353b5e032a42aeb35Affected b801f54917b7c6e8540f877ee562cd0725e62ebd to before 2c29c053a6627dc4f12fcfe6b4860bcd9e5d7503Affected b801f54917b7c6e8540f877ee562cd0725e62ebd to before efdfb1e27a3328085b79540dfe781d537b576ea1Affected
LinuxLinux	2.6.19Affected before 2.6.19Not affected 5.10.271 through 5.10.Not affected 5.15.222 through 5.15.Not affected 6.1.189 through 6.1.Not affected 6.6.158 through 6.6.Not affected 6.12.111 through 6.12.Not affected 6.18.53 through 6.18.Not affected 7.2.7 through 7.2.*Not affected 7.3 and laterNot affected

Product

Versions

LinuxLinux

b801f54917b7c6e8540f877ee562cd0725e62ebd to before 999bc00588cb305ab25065e8a8ac31da7465301cAffected
b801f54917b7c6e8540f877ee562cd0725e62ebd to before f1f2da33eaab54b4d5cdea6d70befb2e2fb49cb6Affected
b801f54917b7c6e8540f877ee562cd0725e62ebd to before 125890702ef4417cd0ffac2e448c0cd4fbf0ac45Affected
b801f54917b7c6e8540f877ee562cd0725e62ebd to before 3080f9e653d8c057d5652db5ced8137f81b3fcbdAffected
b801f54917b7c6e8540f877ee562cd0725e62ebd to before bc8d01d856db106f284b19961af6112e10c3e3b4Affected
b801f54917b7c6e8540f877ee562cd0725e62ebd to before fe9a906d2bff2d2707bafd6353b5e032a42aeb35Affected
b801f54917b7c6e8540f877ee562cd0725e62ebd to before 2c29c053a6627dc4f12fcfe6b4860bcd9e5d7503Affected
b801f54917b7c6e8540f877ee562cd0725e62ebd to before efdfb1e27a3328085b79540dfe781d537b576ea1Affected

LinuxLinux

2.6.19Affected
before 2.6.19Not affected
5.10.271 through 5.10.*Not affected
5.15.222 through 5.15.*Not affected
6.1.189 through 6.1.*Not affected
6.6.158 through 6.6.*Not affected
6.12.111 through 6.12.*Not affected
6.18.53 through 6.18.*Not affected
7.2.7 through 7.2.*Not affected
7.3 and laterNot affected

References

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