CyberSecBulletin
CVE-2026-64576NVD status: Received

Linux: Use of Uninitialized Variable

Published Updated By the CyberSecBulletin desk

CVE-2026-64576 is a high-severity use of uninitialized variable vulnerability in Linux, with a CVSS 3.1 base score of 7.1 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions eacd2e2117e8682f937967fda1022e7f1c22d91a, 37bbd7e1d8df0bec3d187e961783e20c30533d2c, c0936c131a71657afc635d0db2ab096d15d473e1 as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.12% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to eacd2e2117e8682f937967fda1022e7f1c22d91a or 37bbd7e1d8df0bec3d187e961783e20c30533d2c or c0936c131a71657afc635d0db2ab096d15d473e1 or 3081702ea5aca0aeed9c1ade8eadf6cde8db6b7d, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux7c37c7e00411b3d1e0c5292368317aca69d1f324 up to, but not including, eacd2e2117e8682f937967fda1022e7f1c22d91a; 7c37c7e00411b3d1e0c5292368317aca69d1f324 up to, but not including, 37bbd7e1d8df0bec3d187e961783e20c30533d2c; 7c37c7e00411b3d1e0c5292368317aca69d1f324 up to, but not including, c0936c131a71657afc635d0db2ab096d15d473e1; 7c37c7e00411b3d1e0c5292368317aca69d1f324 up to, but not including, 3081702ea5aca0aeed9c1ade8eadf6cde8db6b7d; 7c37c7e00411b3d1e0c5292368317aca69d1f324 up to, but not including, d536bf205c71f700f6de2086038c3e1d77724715; 7c37c7e00411b3d1e0c5292368317aca69d1f324 up to, but not including, 18506d7263768d76ac8e057ba55a4d9da50aad66; 7c37c7e00411b3d1e0c5292368317aca69d1f324 up to, but not including, 6347c5314cee49f364aaf2e40ff15415a57a116e; 5.13eacd2e2117e8682f937967fda1022e7f1c22d91a, 37bbd7e1d8df0bec3d187e961783e20c30533d2c, c0936c131a71657afc635d0db2ab096d15d473e1, 3081702ea5aca0aeed9c1ade8eadf6cde8db6b7d, d536bf205c71f700f6de2086038c3e1d77724715, 18506d7263768d76ac8e057ba55a4d9da50aad66

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
NoneNothing can be modified.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H. Scored by CNA.

Official 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.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Use of Uninitialized Variable

The code uses a variable that has not been initialized, leading to unpredictable or unintended results.

How developers prevent this class of flaw

  • Ensure that critical variables are initialized before first use.
  • Most compilers will complain about the use of uninitialized variables if warnings are turned on.
  • When using a language that does not require explicit declaration of variables, run or compile the software in a mode that reports undeclared or unknown variables. This may indicate the presence of a typographic error in the variable's name.

More Use of Uninitialized Variable vulnerabilities (CWE-457)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Use of Uninitialized Variable vulnerabilities

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