CVE-2026-99074ipv4: stop PMTU walk when nexthop group shrinks
- —Not scoredno CVSS score yet
- 0.15%Exploitation in 30 daysEPSS · top 95% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
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.
Timeline
ID reserved
By Linux
- 28 days later
· 28 days later
Published
- 7 days later
· 7 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
No CVSS score yet: neither the CNA, CISA nor NVD has scored this CVE. NVD status: Received.
- EPSS (exploitation in 30 days)
- 0.15% · top 95% of all CVEs (14 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: Not scored.
Affected products
- affected fc07a232326a623d0be482e307c08ea7049c2846 – < 82d83eec893d8ae84f280aec44c60d9fdecc62b5
- affected b1f7bdee5750d6cbb9497140cd6582abc5fdcb9e – < a411df69524f91fe3adb8f9544d33e701fc9732c
- affected 3bed2abab4a682d426624ce9add9d7b6d475d4e4 – < 7fd60d3c9a1e1b11ef5f1643bbae78d91eae2f4a
- affected 7f5005457b3072fe1ddf15bfef869f2a1d98e05e – < c60d17d6dd61adc761ac6f65a008fefbc54cbf87
- affected 7d3f3b4367f315a61fc615e3138f3d320da8c466 – < c6d670ac656badfd0e15355e07a13a6bdf3b69fd
- affected 7d3f3b4367f315a61fc615e3138f3d320da8c466 – < f27483f9975b5065ff67054cc7eb8edac6083488
- affected 7d3f3b4367f315a61fc615e3138f3d320da8c466 – < 6619e01855e65ef35723685a557e3eb106f4ecf5
- affected 5.15.179 – < 5.15.224
- affected 6.1.129 – < 6.1.191
- affected 6.6.79 – < 6.6.160
- affected 6.12.16 – < 6.12.113
- affected 6.13
- unaffected < 6.13
- unaffected 5.15.224 – ≤ 5.15.*
- unaffected 6.1.191 – ≤ 6.1.*
- unaffected 6.6.160 – ≤ 6.6.*
- unaffected 6.12.113 – ≤ 6.12.*
- unaffected 6.18.57 – ≤ 6.18.*
- unaffected 7.2.11 – ≤ 7.2.*
- unaffected 7.3 – ≤ *
References
References7
- https://git.kernel.org/stable/c/82d83eec893d8ae84f280aec44c60d9fdecc62b5 (opens in a new tab)
- https://git.kernel.org/stable/c/a411df69524f91fe3adb8f9544d33e701fc9732c (opens in a new tab)
- https://git.kernel.org/stable/c/7fd60d3c9a1e1b11ef5f1643bbae78d91eae2f4a (opens in a new tab)
- https://git.kernel.org/stable/c/c60d17d6dd61adc761ac6f65a008fefbc54cbf87 (opens in a new tab)
- https://git.kernel.org/stable/c/c6d670ac656badfd0e15355e07a13a6bdf3b69fd (opens in a new tab)
- https://git.kernel.org/stable/c/f27483f9975b5065ff67054cc7eb8edac6083488 (opens in a new tab)
- https://git.kernel.org/stable/c/6619e01855e65ef35723685a557e3eb106f4ecf5 (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-108740 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
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[](https://cveledger.app/cve/CVE-2026-99074)Record last updated .