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NVD / CVE Program· CNA Linux

CVE-2025-68241: ipv4: route: Prevent rt_bind_exception() from rebinding stale fnhe

Noroxi assessment

Priority: Monitor (action score 30/100)

  • 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: 0.46% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 041ab9ca6e80d8f792bb69df28ebf1ef39c06af8, 0fd16ed6dc331636fb2a874c42d2f7d3156f7ff0, 298f1e0694ab4edb6092d66efed93c4554e6ced1.

Low priority for now. Upgrade to Linux Linux 041ab9ca6e80d8f792bb69df28ebf1ef39c06af8, 0fd16ed6dc331636fb2a874c42d2f7d3156f7ff0, 298f1e0694ab4edb6092d66efed93c4554e6ced1 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: route: Prevent rt_bind_exception() from rebinding stale fnhe The sit driver's packet transmission path calls: sit_tunnel_xmit() -> update_or_create_fnhe(), which lead to fnhe_remove_oldest() being called to delete entries exceeding FNHE_RECLAIM_DEPTH+random. The race window is between fnhe_remove_oldest() selecting fnheX for deletion and the subsequent kfree_rcu(). During this time, the concurrent path's __mkroute_output() -> find_exception() can fetch the soon-to-be-deleted fnheX, and rt_bind_exception() then binds it with a new dst using a dst_hold(). When the original fnheX is freed via RCU, the dst reference remains permanently leaked. CPU 0 CPU 1 __mkroute_output() find_exception() [fnheX] update_or_create_fnhe() fnhe_remove_oldest() [fnheX] rt_bind_exception() [bind dst] RCU callback [fnheX freed, dst leak] This issue manifests as a device reference count leak and a warning in dmesg when unregistering the net device: unregister_netdevice: waiting for sitX to become free. Usage count = N Ido Schimmel provided the simple test validation method [1]. The fix clears 'oldest->fnhe_daddr' before calling fnhe_flush_routes(). Since rt_bind_exception() checks this field, setting it to zero prevents the stale fnhe from being reused and bound to a new dst just before it is freed. [1] ip netns add ns1 ip -n ns1 link set dev lo up ip -n ns1 address add 192.0.2.1/32 dev lo ip -n ns1 link add name dummy1 up type dummy ip -n ns1 route add 192.0.2.2/32 dev dummy1 ip -n ns1 link add name gretap1 up arp off type gretap \ local 192.0.2.1 remote 192.0.2.2 ip -n ns1 route add 198.51.0.0/16 dev gretap1 taskset -c 0 ip netns exec ns1 mausezahn gretap1 \ -A 198.51.100.1 -B 198.51.0.0/16 -t udp -p 1000 -c 0 -q & taskset -c 2 ip netns exec ns1 mausezahn gretap1 \ -A 198.51.100.1 -B 198.51.0.0/16 -t udp -p 1000 -c 0 -q & sleep 10 ip netns pids ns1 | xargs kill ip netns del ns1

HighCVSS 7.5 · v3.1—No exploit Fix available
Published
Dec 16, 2025
Updated
Oct 14, 2026
EPSS
0.4% · 40th percentile
CWE
—

Report tools

JSON

Action score

30

Monitor

Low priority for now.

CVSS
30 / 40 · 7.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.4%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
7.5
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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When you'll hear from us

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  • when exploit code appears or is weaponized
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  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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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

    • bed8941fbdb72a61f6348c4deb0db69c4de87aca, f10ce783bcc4d8ea454563a7d56ae781640e7dcb, f484595be6b7ef9d095a32becabb5dae8204fb2a, 3e6bd2b583f18da9856fc9741ffa200a74a52cba, 5ae06218331f39ec45b5d039aa7cb3ddd4bb8008, 4589a12dcf80af31137ef202be1ff4a321707a73, 5.15affected
    • e46e23c289f62ccd8e2230d9ce652072d777ff30 and later · before 69d35c12168f9c59b159ae566f77dfad9f96d7caaffected · git
    • 5867e20e1808acd0c832ddea2587e5ee49813874 and later · before 4b7210da22429765d19460d38c30eeca72656282affected · git
    • 67d6d681e15b578c1725bad8ad079e05d1c48a8e and later · before 298f1e0694ab4edb6092d66efed93c4554e6ced1affected · git
    • 67d6d681e15b578c1725bad8ad079e05d1c48a8e and later · before b8a44407bdaf2f0c5505cc7d9fc7d8da90cf9a94affected · git
    • 67d6d681e15b578c1725bad8ad079e05d1c48a8e and later · before 041ab9ca6e80d8f792bb69df28ebf1ef39c06af8affected · git
    • 67d6d681e15b578c1725bad8ad079e05d1c48a8e and later · before b84f083f50ecc736a95091691339a1b363962f0eaffected · git
    • 67d6d681e15b578c1725bad8ad079e05d1c48a8e and later · before 0fd16ed6dc331636fb2a874c42d2f7d3156f7ff0affected · git
    • 67d6d681e15b578c1725bad8ad079e05d1c48a8e and later · before ac1499fcd40fe06479e9b933347b837ccabc2a40affected · git
    • 5.4.146 and later · before 5.4.302affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.159-16.1.159-1
Debian:13linuxbefore 6.12.63-16.12.63-1
Debian:14linuxbefore 6.17.9-16.17.9-1

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-2025-68239Dec 16, 2025 · binfmt_misc: restore write access before closing files opened by open_exec()
    0Monitor
  • ← EarlierCVE-2025-68240Dec 16, 2025 · nilfs2: avoid having an active sc_timer before freeing sci
    0Monitor
  • Later →CVE-2025-68242Dec 16, 2025 · NFS: Fix LTP test failures when timestamps are delegated
    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 Linux041ab9ca6e80d8f792bb69df28ebf1ef39c06af8Vendor (CNA)
Linux Linux0fd16ed6dc331636fb2a874c42d2f7d3156f7ff0Vendor (CNA)
Linux Linux298f1e0694ab4edb6092d66efed93c4554e6ced1Vendor (CNA)
Linux Linux4.10Vendor (CNA)
Linux Linux4.15Vendor (CNA)
Linux Linux4.20Vendor (CNA)
Linux Linux4.5Vendor (CNA)
Linux Linux4b7210da22429765d19460d38c30eeca72656282Vendor (CNA)
Linux Linux5.10.247Vendor (CNA)
Linux Linux5.14Vendor (CNA)
Linux Linux5.15Vendor (CNA)
Linux Linux5.4.302Vendor (CNA)
Linux Linux69d35c12168f9c59b159ae566f77dfad9f96d7caVendor (CNA)
Linux Linuxac1499fcd40fe06479e9b933347b837ccabc2a40Vendor (CNA)
Linux Linuxb84f083f50ecc736a95091691339a1b363962f0eVendor (CNA)
Linux Linuxb8a44407bdaf2f0c5505cc7d9fc7d8da90cf9a94Vendor (CNA)
debian:linux6.1.159-1 · Debian:12Package 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.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

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).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

—

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

nvd-secondary

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. Fix✗ → ✓

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

References

Show all references (7 more)

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

All records