CVE-2026-97598
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.
How to fix
- Linux Linux999bc00588cb305ab25065e8a8ac31da7465301c, f1f2da33eaab54b4d5cdea6d70befb2e2fb49cb6, 125890702ef4417cd0ffac2e448c0cd4fbf0ac45, 3080f9e653d8c057d5652db5ced8137f81b3fcbd, bc8d01d856db106f284b19961af6112e10c3e3b4, fe9a906d2bff2d2707bafd6353b5e032a42aeb35, 2c29c053a6627dc4f12fcfe6b4860bcd9e5d7503, efdfb1e27a3328085b79540dfe781d537b576ea1 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| Linux Linux | b801f54917b7c6e8540f877ee562cd0725e62ebd ≤ v < 999bc00588cb305ab25065e8a8ac31da7465301c, b801f54917b7c6e8540f877ee562cd0725e62ebd ≤ v < f1f2da33eaab54b4d5cdea6d70befb2e2fb49cb6, b801f54917b7c6e8540f877ee562cd0725e62ebd ≤ v < 125890702ef4417cd0ffac2e448c0cd4fbf0ac45, b801f54917b7c6e8540f877ee562cd0725e62ebd ≤ v < 3080f9e653d8c057d5652db5ced8137f81b3fcbd, b801f54917b7c6e8540f877ee562cd0725e62ebd ≤ v < bc8d01d856db106f284b19961af6112e10c3e3b4, b801f54917b7c6e8540f877ee562cd0725e62ebd ≤ v < fe9a906d2bff2d2707bafd6353b5e032a42aeb35, b801f54917b7c6e8540f877ee562cd0725e62ebd ≤ v < 2c29c053a6627dc4f12fcfe6b4860bcd9e5d7503, b801f54917b7c6e8540f877ee562cd0725e62ebd ≤ v < efdfb1e27a3328085b79540dfe781d537b576ea1, 2.6.19 | 999bc00588cb305ab25065e8a8ac31da7465301c, f1f2da33eaab54b4d5cdea6d70befb2e2fb49cb6, 125890702ef4417cd0ffac2e448c0cd4fbf0ac45, 3080f9e653d8c057d5652db5ced8137f81b3fcbd, bc8d01d856db106f284b19961af6112e10c3e3b4, fe9a906d2bff2d2707bafd6353b5e032a42aeb35, 2c29c053a6627dc4f12fcfe6b4860bcd9e5d7503, efdfb1e27a3328085b79540dfe781d537b576ea1 |
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