CVE-2026-72429: ipv6: ioam: fix type confusion of dst_entry
In the Linux kernel, the following vulnerability has been resolved:
ipv6: ioam: fix type confusion of dstentry
IOAM uses a dummy dstentry(nulldst) to mark that the destination should not be changed after the transformation. This dst is stored in the IOAM lwt state and may be passed to dstcachesetip6().
However, the IPv6 dst cache path eventually calls rt6getcookie(), which treats the dstentry as part of a struct rt6info. Since the nulldst was embedded directly as a struct dstentry in struct ioam6lwt, this resulted in an invalid cast and rt6getcookie() reading fields from the wrong object.
In practice, the wrong cookie is not used while dst->obsolete is zero, but rt6getcookie() may also access per-cpu value when rt->sernum is zero. In this case, rt->sernum aliases ioam6lwt::cache::resetts, which can become zero, making this a potential invalid pointer access.
Fix this by embedding a full struct rt6info for the dummy IPv6 route and passing its dst member to the dst APIs.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
ubuntu/linux-aws-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1013.13~24.04.1 - Upgrade
Upgrade
ubuntu/linux-azure-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1017.17~24.04.1 - Upgrade
Upgrade
ubuntu/linux-azure-fde-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1016.16~24.04.1 - Upgrade
Upgrade
ubuntu/linux-gcp-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1013.13~24.04.1 - Upgrade
Upgrade
ubuntu/linux-hwe-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-34.34~24.04.1 - Upgrade
Upgrade
ubuntu/linux-nvidia-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1024.25~24.04.1 - Upgrade
Upgrade
ubuntu/linux-oracle-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1012.12~24.04.1 - Upgrade
Upgrade
ubuntu/linux-riscv-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-34.34.1~24.04.1 - Upgrade
Upgrade
ubuntu/linuxto a version that resolves this vulnerability.Fixed in 7.0.0-34.34 - Upgrade
Upgrade
ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 7.0.0-1013.13 - Upgrade
Upgrade
ubuntu/linux-azureto a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
Upgrade
ubuntu/linux-azure-fdeto a version that resolves this vulnerability.Fixed in 7.0.0-1016.16 - Upgrade
Upgrade
ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 7.0.0-1013.13 - Upgrade
Upgrade
ubuntu/linux-gketo a version that resolves this vulnerability.Fixed in 7.0.0-1007.8 - Upgrade
Upgrade
ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 7.0.0-1014.14 - Upgrade
Upgrade
ubuntu/linux-nvidia-bosto a version that resolves this vulnerability.Fixed in 7.0.0-2022.23 - Upgrade
Upgrade
ubuntu/linux-oem-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1014.14 - Upgrade
Upgrade
ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 7.0.0-1012.12 - Upgrade
Upgrade
ubuntu/linux-raspito a version that resolves this vulnerability.Fixed in 7.0.0-1020.20 - Upgrade
Upgrade
ubuntu/linux-realtimeto a version that resolves this vulnerability.Fixed in 7.0.0-34.34.1 - Upgrade
Upgrade
ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-34.34.1 - Compensating control
Fix the IPv6 IOAM dst_entry type confusion by embedding a full struct rt6_info for the dummy IPv6 route in struct ioam6_lwt, and pass its dst member to the dst APIs, including dst_cache_set_ip6().
Event History
Frequently Asked Questions
What is the severity of CVE-2026-72429?
CVE-2026-72429 has a risk score of 34.
How do I fix CVE-2026-72429?
To fix CVE-2026-72429, update your Linux kernel to the latest version provided by your distribution that addresses this vulnerability.
What systems are affected by CVE-2026-72429?
CVE-2026-72429 affects systems running the vulnerable versions of the Linux kernel with IOAM capabilities.
What type of issue is CVE-2026-72429?
CVE-2026-72429 is a type confusion vulnerability related to IPv6's IOAM feature in the Linux kernel.
When was CVE-2026-72429 published?
CVE-2026-72429 was published on August 15, 2026.