CVE-2025-38588 ipv6: prevent infinite loop in rt6_nlmsg_size()

What is CVE-2025-38588?

CVE-2025-38588 is a medium-severity denial of service vulnerability in Debian Debian Linux, published on 19 Aug 2025. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

In the Linux kernel, the following vulnerability has been resolved:

ipv6: prevent infinite loop in rt6_nlmsg_size()

While testing prior patch, I was able to trigger an infinite loop in rt6_nlmsg_size() in the following place:

list_for_each_entry_rcu(sibling, &f6i->fib6_siblings, fib6_siblings) { rt6_nh_nlmsg_size(sibling->fib6_nh, &nexthop_len); }

This is because fib6_del_route() and fib6_add_rt2node() uses list_del_rcu(), which can confuse rcu readers, because they might no longer see the head of the list.

Restart the loop if f6i->fib6_nsiblings is zero.

Weakness: CWE-835

Which versions are affected by CVE-2025-38588?

It affects 2 products.

Products include Debian Debian Linux, Linux kernel.

How do I fix CVE-2025-38588?

Apply the vendor's patch.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2025-38588 being exploited?

There is no known exploitation of CVE-2025-38588 in the wild and no public exploit code.

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All Debian Debian Linux vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BELL-CVE-2025-38588, DEBIAN-CVE-2025-38588, GHSA-xmch-89f7-f57m, ROOT-OS-DEBIAN-12-CVE-2025-38588, ROOT-OS-DEBIAN-13-CVE-2025-38588, ROOT-OS-UBUNTU-2404-CVE-2025-38588 and 13 more.