CVE-2026-98603: ovpn: replace bind when clearing stale local source
In the Linux kernel, the following vulnerability has been resolved:
ovpn: replace bind when clearing stale local source
The UDP output fallback clears bind->local in place when the remembered source address is no longer usable. The bind is RCU-published and read locklessly by concurrent TX, so an IPv6 reader can observe a torn address.
Retry the route lookup with source address autoselection without modifying the bind. After a successful lookup, revalidate the bind and route key under peer->lock, reset the dst cache, and best-effort publish a replacement bind with a wildcard local address.
Do not cache the resolved dst when clearing the local source. Replacing the source invalidates all per-CPU cache entries, while dstcachesetip4 and dstcachesetip6 update only the current CPU slot. The current packet can still use the resolved route; if bind allocation fails, a later cache miss retries the repair.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
ubuntu/linux-hwe-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-42.42~24.04.1 - Upgrade
Upgrade
ubuntu/linux-riscv-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1~24.04.1 - Upgrade
Upgrade
ubuntu/linuxto a version that resolves this vulnerability.Fixed in 7.0.0-42.42 - Upgrade
Upgrade
ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 7.0.0-1016.17 - Upgrade
Upgrade
ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 7.0.0-1016.18 - Upgrade
Upgrade
ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
Upgrade
ubuntu/linux-oem-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
Upgrade
ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 7.0.0-1015.16 - Upgrade
Upgrade
ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1
Event History
Frequently Asked Questions
Which systems are exposed to this issue?
Systems using the Linux kernel's ovpn component with UDP output are exposed when a remembered local source address becomes unusable and the fallback path clears that source while concurrent transmit operations read the RCU-published bind.
What must occur for the race condition to be triggered?
A stale remembered local source address must require UDP route-lookup fallback, while concurrent TX reads the bind locklessly. The described impact specifically involves an IPv6 reader observing a torn address during the in-place update.
What mitigation is available if the kernel fix cannot be deployed immediately?
The provided information does not identify a configuration workaround. The resolved implementation avoids modifying the published bind in place and instead publishes a replacement bind with a wildcard local address after route lookup succeeds.