ipv4: fib: bound automatic table ID allocation

Answer in brief

CVE-2026-97598 records a Unknown severity vulnerability in ipv4: fib: bound automatic table ID allocation. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 25, 2026Updated Sep 25, 2026Source checked Sep 25, 2026First seen by HOL Sep 25, 2026Material review Sep 25, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Linux/Linuxgeneric	>=b801f54917b7c6e8540f877ee562cd0725e62ebd <bc8d01d856db106f284b19961af6112e10c3e3b4 \|\| >=b801f54917b7c6e8540f877ee562cd0725e62ebd <fe9a906d2bff2d2707bafd6353b5e032a42aeb35 \|\| >=b801f54917b7c6e8540f877ee562cd0725e62ebd <2c29c053a6627dc4f12fcfe6b4860bcd9e5d7503 \|\| >=b801f54917b7c6e8540f877ee562cd0725e62ebd <efdfb1e27a3328085b79540dfe781d537b576ea1	bc8d01d856db106f284b19961af6112e10c3e3b4, fe9a906d2bff2d2707bafd6353b5e032a42aeb35, 2c29c053a6627dc4f12fcfe6b4860bcd9e5d7503, efdfb1e27a3328085b79540dfe781d537b576ea1
Linux/Linuxgeneric	2.6.19	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to bc8d01d856db106f284b19961af6112e10c3e3b4 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 25, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 25, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 25, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.