CVE-2021-47291 ipv6: fix another slab-out-of-bounds in fib6_nh_flush_exceptions

What is CVE-2021-47291?

CVE-2021-47291 is a high-severity memory corruption vulnerability in Linux kernel, published on 21 May 2024. 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: fix another slab-out-of-bounds in fib6_nh_flush_exceptions

While running the self-tests on a KASAN enabled kernel, I observed a slab-out-of-bounds splat very similar to the one reported in commit 821bbf79fe46 ("ipv6: Fix KASAN: slab-out-of-bounds Read in fib6_nh_flush_exceptions").

We additionally need to take care of fib6_metrics initialization failure when the caller provides an nh.

The fix is similar, explicitly free the route instead of calling fib6_info_release on a half-initialized object.

Weakness: CWE-125

Which versions are affected by CVE-2021-47291?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2021-47291?

Apply the vendor's patch.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2021-47291 being exploited?

There is no known exploitation of CVE-2021-47291 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

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

Also known as DEBIAN-CVE-2021-47291, GHSA-29rx-6chj-44xc, UBUNTU-CVE-2021-47291.