Answer in brief
CVE-2026-99074 records a Unknown severity vulnerability in ipv4: stop PMTU walk when nexthop group shrinks. 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.
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.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=3bed2abab4a682d426624ce9add9d7b6d475d4e4 <7fd60d3c9a1e1b11ef5f1643bbae78d91eae2f4a || >=7f5005457b3072fe1ddf15bfef869f2a1d98e05e <c60d17d6dd61adc761ac6f65a008fefbc54cbf87 || >=7d3f3b4367f315a61fc615e3138f3d320da8c466 <c6d670ac656badfd0e15355e07a13a6bdf3b69fd || >=7d3f3b4367f315a61fc615e3138f3d320da8c466 <f27483f9975b5065ff67054cc7eb8edac6083488 || >=7d3f3b4367f315a61fc615e3138f3d320da8c466 <6619e01855e65ef35723685a557e3eb106f4ecf5 || fc07a232326a623d0be482e307c08ea7049c2846 || b1f7bdee5750d6cbb9497140cd6582abc5fdcb9e || >=6.6.79 <6.6.160 || >=6.12.16 <6.12.113 || >=5.15.179 <5.16 || >=6.1.129 <6.2 | 7fd60d3c9a1e1b11ef5f1643bbae78d91eae2f4a, c60d17d6dd61adc761ac6f65a008fefbc54cbf87, c6d670ac656badfd0e15355e07a13a6bdf3b69fd, f27483f9975b5065ff67054cc7eb8edac6083488, 6619e01855e65ef35723685a557e3eb106f4ecf5, 6.6.160, 6.12.113, 5.16, 6.2 |
| Linux/Linuxgeneric | 6.13 | Not reported |
Published upstream
Oct 23, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 23, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Oct 23, 2026
In the Linux kernel, the following vulnerability has been resolved: ipv4: stop PMTU walk when nexthop group shrinks Commit 7d3f3b4367f3 ("net: ipv4: Cache pmtu for all packet paths if multipath enabled") made __ip_rt_update_pmtu() update every path. For nexthop objects, fib_info_num_path() and fib_info_nhc() independently load nh->nh_grp. RCU protects each group's lifetime but does not make the loads observe the same group. If replacement shrinks the group after the loop accepts an index, fib_info_nhc() returns NULL and update_or_create_fnhe() dereferences it. A deterministic probe only widened the existing window between the real operations. On v7.2, an RTM_NEWNEXTHOP replacement published a one-member group after the PMTU reader accepted index 1 from a two-member group, producing: KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] RIP: update_or_create_fnhe+0x45/0x15b0 Stop when the indexed path is absent. Groups are dense, so no later index exists in that snapshot. The same real-writer window completed 114,423 PMTU iterations without an oops with this check. A reproducer is available on request. Replacement requires CAP_NET_ADMIN in the network namespace. Where unprivileged user namespaces are permitted, a local user can obtain it in a new user and network namespace.
Quoted source text, attributed separately from HOL analysis.