CVE-2026-64576

nexthop: initialize extack in nh_res_bucket_migrate()

State: Published
Severity: 7.1 High
Published: Aug 5, 2026
Updated: Oct 19, 2026
Reserved: Jul 19, 2026

Description

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

nexthop: initialize extack in nh_res_bucket_migrate()

nh_res_bucket_migrate() passes an uninitialized netlink_ext_ack to call_nexthop_res_bucket_notifiers(). When nh_notifier_res_bucket_info_init() fails (e.g. the kzalloc returns -ENOMEM), the error is propagated back before any notifier sets extack._msg, and the error path formats the stale pointer with pr_err_ratelimited("%s\n", extack._msg). With CONFIG_INIT_STACK_NONE this dereferences uninitialized stack memory:

Oops: general protection fault, probably for non-canonical address ... KASAN: maybe wild-memory-access in range [...] RIP: 0010:string (lib/vsprintf.c:730) vsnprintf (lib/vsprintf.c:2945) _printk (kernel/printk/printk.c:2504) nh_res_bucket_migrate (net/ipv4/nexthop.c:1816) nh_res_table_upkeep (net/ipv4/nexthop.c:1866) rtm_new_nexthop (net/ipv4/nexthop.c:3323) rtnetlink_rcv_msg (net/core/rtnetlink.c:7076) netlink_sendmsg (net/netlink/af_netlink.c:1900) Kernel panic - not syncing: Fatal exception

Zero-initialize extack so _msg is NULL on error paths that never set it.

Scores

CVSS	Score	Vector	Source
3.1	7.1 High	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H	Linux

Weaknesses

CWE-457 Use of Uninitialized Variable

Affected Products

Product	Versions
LinuxLinux	7c37c7e00411b3d1e0c5292368317aca69d1f324 to before eacd2e2117e8682f937967fda1022e7f1c22d91aAffected 7c37c7e00411b3d1e0c5292368317aca69d1f324 to before 37bbd7e1d8df0bec3d187e961783e20c30533d2cAffected 7c37c7e00411b3d1e0c5292368317aca69d1f324 to before c0936c131a71657afc635d0db2ab096d15d473e1Affected 7c37c7e00411b3d1e0c5292368317aca69d1f324 to before 3081702ea5aca0aeed9c1ade8eadf6cde8db6b7dAffected 7c37c7e00411b3d1e0c5292368317aca69d1f324 to before d536bf205c71f700f6de2086038c3e1d77724715Affected 7c37c7e00411b3d1e0c5292368317aca69d1f324 to before 18506d7263768d76ac8e057ba55a4d9da50aad66Affected 7c37c7e00411b3d1e0c5292368317aca69d1f324 to before 6347c5314cee49f364aaf2e40ff15415a57a116eAffected
LinuxLinux	5.13Affected before 5.13Not affected 5.15.216 through 5.15.Not affected 6.1.183 through 6.1.Not affected 6.6.148 through 6.6.Not affected 6.12.101 through 6.12.Not affected 6.18.42 through 6.18.Not affected 7.1.6 through 7.1.Not affected 7.2 and laterNot affected

Product

Versions

LinuxLinux

7c37c7e00411b3d1e0c5292368317aca69d1f324 to before eacd2e2117e8682f937967fda1022e7f1c22d91aAffected
7c37c7e00411b3d1e0c5292368317aca69d1f324 to before 37bbd7e1d8df0bec3d187e961783e20c30533d2cAffected
7c37c7e00411b3d1e0c5292368317aca69d1f324 to before c0936c131a71657afc635d0db2ab096d15d473e1Affected
7c37c7e00411b3d1e0c5292368317aca69d1f324 to before 3081702ea5aca0aeed9c1ade8eadf6cde8db6b7dAffected
7c37c7e00411b3d1e0c5292368317aca69d1f324 to before d536bf205c71f700f6de2086038c3e1d77724715Affected
7c37c7e00411b3d1e0c5292368317aca69d1f324 to before 18506d7263768d76ac8e057ba55a4d9da50aad66Affected
7c37c7e00411b3d1e0c5292368317aca69d1f324 to before 6347c5314cee49f364aaf2e40ff15415a57a116eAffected

LinuxLinux

5.13Affected
before 5.13Not affected
5.15.216 through 5.15.*Not affected
6.1.183 through 6.1.*Not affected
6.6.148 through 6.6.*Not affected
6.12.101 through 6.12.*Not affected
6.18.42 through 6.18.*Not affected
7.1.6 through 7.1.*Not affected
7.2 and laterNot affected

References

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