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

CVE-2026-98598: ipv6: Prevent rt6_insert_exception() for dying fib6_info.

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: 0.19% (FIRST EPSS).
  • Fixed version: Linux Linux 0346ec2f080b40d95ed05b853bb9226289e75212, 649ffc76ed5483b2caf35ed90d3787538efc4e53, e03e77071e75ce726d877f0a4349a28b6e1f487a; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 Release Notes; azl3 kernel 6.6.159.1-1 on Azure Linux 3.0 Release Notes.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 0346ec2f080b40d95ed05b853bb9226289e75212, 649ffc76ed5483b2caf35ed90d3787538efc4e53, e03e77071e75ce726d877f0a4349a28b6e1f487a; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 Release Notes; azl3 kernel 6.6.159.1-1 on Azure Linux 3.0 Release Notes 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: ipv6: Prevent rt6_insert_exception() for dying fib6_info. Before the cited commit, fib6_nh_flush_exceptions() always set from->exception_bucket_flushed = 1 under rt6_exception_lock to prevent rt6_insert_exception() from inserting a new exception for a dying fib6_info. The flag was replaced with the FIB6_EXCEPTION_BUCKET_FLUSHED bit stored in nh->rt6i_exception_bucket. The problem is that now the bit is only set when the bucket is not NULL and fib6_nh_flush_exceptions() is called from fib6_nh_release() after fib6_ref has already reached zero. If rt6_insert_exception() is called while the target fib6_info is being removed via fib6_purge_rt(), a new exception could be created successfully because rt6_flush_exceptions() no longer sets the bit. This creates a reference cycle between the fib6_info and the exception route, leaking the fib6_info, its nexthop device, and all per-CPU routes in fib6_nh->rt6i_pcpu, which stalls netdev unregistration. [ 34.680602] unregister_netdevice: waiting for gre6 to become free. Usage count = 68 [ 44.920675] unregister_netdevice: waiting for gre6 to become free. Usage count = 68 [ 55.176582] unregister_netdevice: waiting for gre6 to become free. Usage count = 68 Let's call fib6_drop_pcpu_from() before rt6_flush_exceptions(), to set fib6_destroying before rt6_exception_lock, and check f6i->fib6_destroying in rt6_insert_exception(). Note that FIB6_EXCEPTION_BUCKET_FLUSHED logic is dead and we can clean it up in net-next.

—No exploit Fix available
Published
Oct 18, 2026
Updated
Oct 19, 2026
EPSS
0.1% · 9th 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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Noroxi analysis

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Affected systems

Is your version affected?

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—

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

    • 5.3affected
    • cc5c073a693fa6ed7a207b0436114f68cce72434 and later · before 649ffc76ed5483b2caf35ed90d3787538efc4e53affected · git
    • cc5c073a693fa6ed7a207b0436114f68cce72434 and later · before e03e77071e75ce726d877f0a4349a28b6e1f487aaffected · git
    • cc5c073a693fa6ed7a207b0436114f68cce72434 and later · before 0346ec2f080b40d95ed05b853bb9226289e75212affected · git
    • before 5.3not affected · semver
    • 6.18.55 and later · up to and including 6.18.*not affected · semver
    • 7.2.9 and later · up to and including 7.2.*not affected · semver
    • 7.3 and laternot affected · original_commit_for_fix

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxfrom 0—
Debian:14linuxbefore 7.2.9-17.2.9-1

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-2026-98596Oct 18, 2026 · ipv6: Fix dst leak for uncached routes.
    0Monitor
  • ← EarlierCVE-2026-98597Oct 18, 2026 · net: usb: sr9700: include receive overhead in the length check
    0Monitor
  • Later →CVE-2026-98599Oct 18, 2026 · bpf: Reject non-negative offsets in stack_slot_obj_get_spi()
    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 Linux0346ec2f080b40d95ed05b853bb9226289e75212Vendor (CNA)
Linux Linux649ffc76ed5483b2caf35ed90d3787538efc4e53Vendor (CNA)
Linux Linuxe03e77071e75ce726d877f0a4349a28b6e1f487aVendor (CNA)
azl3 kernel 6.6.157.1-1 on Azure Linux 3.0Release NotesMicrosoft (MSRC)
azl3 kernel 6.6.159.1-1 on Azure Linux 3.0Release NotesMicrosoft (MSRC)
debian:linux7.2.9-1 · Debian:14Package 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. TodayNov 6, 2026+19 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

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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.

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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.

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Change log

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

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References

Show all references (2 more)

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

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