CVE-2026-98598
Received
Received - Intake
Memory Leak in Linux Kernel IPv6 Routing
Vulnerability report for CVE-2026-98598, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-10-18
Last updated on: 2026-10-19
Assigner: kernel.org
Description
Description
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.
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| Linux | Linux | cc5c073a693fa6ed7a207b0436114f68cce72434 |
| Linux | Linux | cc5c073a693fa6ed7a207b0436114f68cce72434 |
| Linux | Linux | cc5c073a693fa6ed7a207b0436114f68cce72434 |
| Linux | Linux | 5.3 |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-UNKNOWN |
