CVE-2026-64538
ipv6: Fix null-ptr-deref in fib6_nh_mtu_change().
Description
In the Linux kernel, the following vulnerability has been resolved: ipv6: Fix null-ptr-deref in fib6_nh_mtu_change(). fib6_nh_mtu_change() re-fetches idev via __in6_dev_get(arg->dev) and dereferences idev->cnf.mtu6 without a NULL check. addrconf_ifdown() clears dev->ip6_ptr with RCU_INIT_POINTER() after rt6_disable_ip() has released tb6_lock, so the RA-driven MTU walk can observe a NULL idev and oops. The caller rt6_mtu_change_route() guards its own __in6_dev_get(), but this re-fetch is unguarded; nexthop-backed routes survive addrconf_ifdown()'s flush, so the walk still reaches it after ip6_ptr is nulled. Return 0 when idev is NULL, matching rt6_mtu_change_route() and the fib6_mtu() fix in commit 5ad509c1fdad ("ipv6: Fix null-ptr-deref in fib6_mtu()."). Oops: general protection fault, ... KASAN: null-ptr-deref in range [0x00000000000002a8-0x00000000000002af] RIP: 0010:fib6_nh_mtu_change+0x203/0x990 rt6_mtu_change_route+0x141/0x1d0 __fib6_clean_all+0xd0/0x160 rt6_mtu_change+0xb4/0x100 ndisc_router_discovery+0x24b5/0x2cb0 icmpv6_rcv+0x12e9/0x1710 ipv6_rcv+0x39b/0x410
INFO
Published Date :
July 27, 2026, 9:17 p.m.
Last Modified :
July 27, 2026, 9:17 p.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Affected Products
The following products are affected by CVE-2026-64538
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
Solution
- Update the Linux kernel to the resolved version.
- Recompile the kernel if necessary.
- Deploy the updated kernel.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-64538.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-64538 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-64538
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-64538 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-64538 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Jul. 27, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': 'c0b220cf7d80eb8a36ae9f12cae6df4577a6814e', 'lessThan': 'd08d019f2f43a6f9a71e81868bbc326b3afaf37b', 'versionType': 'git'}, {'status': 'affected', 'version': 'c0b220cf7d80eb8a36ae9f12cae6df4577a6814e', 'lessThan': '1451deca9896957159f0666520a792c1b861af4f', 'versionType': 'git'}, {'status': 'affected', 'version': 'c0b220cf7d80eb8a36ae9f12cae6df4577a6814e', 'lessThan': 'b2c70dd3326809429b709a9c7e9220d29923051a', 'versionType': 'git'}, {'status': 'affected', 'version': 'c0b220cf7d80eb8a36ae9f12cae6df4577a6814e', 'lessThan': '302d57ed7872838b40e56a868fb4c7da7da606e9', 'versionType': 'git'}, {'status': 'affected', 'version': 'c0b220cf7d80eb8a36ae9f12cae6df4577a6814e', 'lessThan': '80600b5d0f3ecb9324120dc95b5e915130f516c5', 'versionType': 'git'}, {'status': 'affected', 'version': 'c0b220cf7d80eb8a36ae9f12cae6df4577a6814e', 'lessThan': 'b0d0eb13a0441a8ebf4f227843deaf494f1e2c33', 'versionType': 'git'}, {'status': 'affected', 'version': 'c0b220cf7d80eb8a36ae9f12cae6df4577a6814e', 'lessThan': '6428634f7a0b7878144b4925c37856bef3224967', 'versionType': 'git'}, {'status': 'affected', 'version': 'c0b220cf7d80eb8a36ae9f12cae6df4577a6814e', 'lessThan': '46c3b8191aad3d032776bf3bebf03efdf5f4b905', 'versionType': 'git'}], 'programFiles': ['net/ipv6/route.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '5.3'}, {'status': 'unaffected', 'version': '0', 'lessThan': '5.3', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '5.10.261', 'versionType': 'semver', 'lessThanOrEqual': '5.10.*'}, {'status': 'unaffected', 'version': '5.15.212', 'versionType': 'semver', 'lessThanOrEqual': '5.15.*'}, {'status': 'unaffected', 'version': '6.1.178', 'versionType': 'semver', 'lessThanOrEqual': '6.1.*'}, {'status': 'unaffected', 'version': '6.6.145', 'versionType': 'semver', 'lessThanOrEqual': '6.6.*'}, {'status': 'unaffected', 'version': '6.12.97', 'versionType': 'semver', 'lessThanOrEqual': '6.12.*'}, {'status': 'unaffected', 'version': '6.18.40', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.1.5', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2-rc1', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['net/ipv6/route.c'], 'defaultStatus': 'affected'}] Added Description In the Linux kernel, the following vulnerability has been resolved: ipv6: Fix null-ptr-deref in fib6_nh_mtu_change(). fib6_nh_mtu_change() re-fetches idev via __in6_dev_get(arg->dev) and dereferences idev->cnf.mtu6 without a NULL check. addrconf_ifdown() clears dev->ip6_ptr with RCU_INIT_POINTER() after rt6_disable_ip() has released tb6_lock, so the RA-driven MTU walk can observe a NULL idev and oops. The caller rt6_mtu_change_route() guards its own __in6_dev_get(), but this re-fetch is unguarded; nexthop-backed routes survive addrconf_ifdown()'s flush, so the walk still reaches it after ip6_ptr is nulled. Return 0 when idev is NULL, matching rt6_mtu_change_route() and the fib6_mtu() fix in commit 5ad509c1fdad ("ipv6: Fix null-ptr-deref in fib6_mtu()."). Oops: general protection fault, ... KASAN: null-ptr-deref in range [0x00000000000002a8-0x00000000000002af] RIP: 0010:fib6_nh_mtu_change+0x203/0x990 rt6_mtu_change_route+0x141/0x1d0 __fib6_clean_all+0xd0/0x160 rt6_mtu_change+0xb4/0x100 ndisc_router_discovery+0x24b5/0x2cb0 icmpv6_rcv+0x12e9/0x1710 ipv6_rcv+0x39b/0x410 Added Reference https://git.kernel.org/stable/c/1451deca9896957159f0666520a792c1b861af4f Added Reference https://git.kernel.org/stable/c/302d57ed7872838b40e56a868fb4c7da7da606e9 Added Reference https://git.kernel.org/stable/c/46c3b8191aad3d032776bf3bebf03efdf5f4b905 Added Reference https://git.kernel.org/stable/c/6428634f7a0b7878144b4925c37856bef3224967 Added Reference https://git.kernel.org/stable/c/80600b5d0f3ecb9324120dc95b5e915130f516c5 Added Reference https://git.kernel.org/stable/c/b0d0eb13a0441a8ebf4f227843deaf494f1e2c33 Added Reference https://git.kernel.org/stable/c/b2c70dd3326809429b709a9c7e9220d29923051a Added Reference https://git.kernel.org/stable/c/d08d019f2f43a6f9a71e81868bbc326b3afaf37b