CVE-2026-23459
Received Received - Intake
Race Condition in Linux Kernel ip_tunnel Causes System Freeze

Publication date: 2026-04-03

Last updated on: 2026-04-27

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: ip_tunnel: adapt iptunnel_xmit_stats() to NETDEV_PCPU_STAT_DSTATS Blamed commits forgot that vxlan/geneve use udp_tunnel[6]_xmit_skb() which call iptunnel_xmit_stats(). iptunnel_xmit_stats() was assuming tunnels were only using NETDEV_PCPU_STAT_TSTATS. @syncp offset in pcpu_sw_netstats and pcpu_dstats is different. 32bit kernels would either have corruptions or freezes if the syncp sequence was overwritten. This patch also moves pcpu_stat_type closer to dev->{t,d}stats to avoid a potential cache line miss since iptunnel_xmit_stats() needs to read it.
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Meta Information
Published
2026-04-03
Last Modified
2026-04-27
Generated
2026-05-07
AI Q&A
2026-04-03
EPSS Evaluated
2026-05-05
NVD
CVE-2026-23459
EUVD
EUVD-2026-18718
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-UNKNOWN
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability is in the Linux kernel's IP tunnel code, specifically in the function iptunnel_xmit_stats(). The function was originally designed assuming that tunnels only used NETDEV_PCPU_STAT_TSTATS, but it did not account for vxlan and geneve tunnels that use udp_tunnel[6]_xmit_skb(), which also calls iptunnel_xmit_stats().

Because of differences in how synchronization primitives (@syncp) offset the per-CPU software network statistics (pcpu_sw_netstats) and per-CPU device statistics (pcpu_dstats), 32-bit kernels could experience data corruption or system freezes if the synchronization sequence was overwritten.

The patch that fixed this issue also improved performance by moving the pcpu_stat_type closer to the device's stats to avoid potential cache line misses.


How can this vulnerability impact me? :

This vulnerability can cause data corruption or system freezes on 32-bit Linux kernels when using certain network tunnels like vxlan or geneve. This can lead to instability or crashes in systems relying on these tunneling protocols.


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