What’s Vulnerable › Vulnerabilities

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

• Severity: high (CVSS 7.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2024-05-21 · updated 2026-08-04
• Weakness: CWE-125

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.

Affected products

• Linux kernel: from 5.3 before 5.4.136; from 5.5 before 5.10.54; from 5.11 before 5.13.6; 5.14-rc1, 5.14-rc2 — fixed in 5.10.54, 5.13.6, 5.4.136

How to fix

Upgrade to a fixed version: Linux kernel 5.10.54, 5.13.6, 5.4.136. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/115784bcccf135c3a3548098153413d76f16aae0
• https://git.kernel.org/stable/c/830251361425c5be044db4d826aaf304ea3d14c6
• https://git.kernel.org/stable/c/8fb4792f091e608a0a1d353dfdf07ef55a719db5
• https://git.kernel.org/stable/c/ce8fafb68051fba52546f8bbe8621f7641683680
• https://git.kernel.org/stable/c/115784bcccf135c3a3548098153413d76f16aae0
• https://git.kernel.org/stable/c/830251361425c5be044db4d826aaf304ea3d14c6
• https://git.kernel.org/stable/c/8fb4792f091e608a0a1d353dfdf07ef55a719db5
• https://git.kernel.org/stable/c/ce8fafb68051fba52546f8bbe8621f7641683680

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