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CVE.org (no NVD analysis yet)· CNA Linux

CVE-2026-99074: ipv4: stop PMTU walk when nexthop group shrinks

Noroxi assessment

Priority: Monitor (action score 0/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.15% (FIRST EPSS).
  • Fixed version: Linux Linux 5.16, 6.12.113, 6.2.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 5.16, 6.12.113, 6.2 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

—No exploit Fix available
Published
Oct 23, 2026
Updated
Oct 23, 2026
EPSS
0.1% · 4th percentile
CWE
—

Report tools

JSON

Action score

0

Monitor

Low priority for now.

CVSS
0 / 40 · —
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

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  • A fix has been released

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Noroxi analysis

What does it mean in your environment?

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • fc07a232326a623d0be482e307c08ea7049c2846, b1f7bdee5750d6cbb9497140cd6582abc5fdcb9e, 6.13affected
    • 3bed2abab4a682d426624ce9add9d7b6d475d4e4 and later · before 7fd60d3c9a1e1b11ef5f1643bbae78d91eae2f4aaffected · git
    • 7f5005457b3072fe1ddf15bfef869f2a1d98e05e and later · before c60d17d6dd61adc761ac6f65a008fefbc54cbf87affected · git
    • 7d3f3b4367f315a61fc615e3138f3d320da8c466 and later · before c6d670ac656badfd0e15355e07a13a6bdf3b69fdaffected · git
    • 7d3f3b4367f315a61fc615e3138f3d320da8c466 and later · before f27483f9975b5065ff67054cc7eb8edac6083488affected · git
    • 7d3f3b4367f315a61fc615e3138f3d320da8c466 and later · before 6619e01855e65ef35723685a557e3eb106f4ecf5affected · git
    • 6.6.79 and later · before 6.6.160affected · semver
    • 6.12.16 and later · before 6.12.113affected · semver
    • 5.15.179 and later · before 5.16affected · semver
    • 6.1.129 and later · before 6.2affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxfrom 0—
Debian:13linuxbefore 6.12.113-16.12.113-1
Debian:14linuxbefore 7.2.11-17.2.11-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-99072Oct 23, 2026 · ipv4: stop route notification sizing when nexthop group shrinks
    0Monitor
  • ← EarlierCVE-2026-99073Oct 23, 2026 · ipv4: stop exception dump when nexthop group shrinks
    0Monitor
  • Later →CVE-2026-99075Oct 23, 2026 · rust_binder: reschedule node refcount update on thread exit
    0Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux5.16Vendor (CNA)
Linux Linux6.12.113Vendor (CNA)
Linux Linux6.2Vendor (CNA)
Linux Linux6.6.160Vendor (CNA)
Linux Linux6619e01855e65ef35723685a557e3eb106f4ecf5Vendor (CNA)
Linux Linux7fd60d3c9a1e1b11ef5f1643bbae78d91eae2f4aVendor (CNA)
Linux Linuxc60d17d6dd61adc761ac6f65a008fefbc54cbf87Vendor (CNA)
Linux Linuxc6d670ac656badfd0e15355e07a13a6bdf3b69fdVendor (CNA)
Linux Linuxf27483f9975b5065ff67054cc7eb8edac6083488Vendor (CNA)
debian:linux6.12.113-1 · Debian:13Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. Published
  2. Fix recordedsame day
  3. TodayOct 28, 2026+5 d
EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

No CVSS vector for this record, so attack conditions can't be derived.

Weakness class (CWE)

—

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Exploit maturity— → none
  2. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (4 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records