VulnerabilityPublished 25 Sep 2026Updated 21 Oct 2026

CVE-2026-97938: Linux kernel · reboot: fix cad_pid use-after-free race

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in ae3e53fe3c1241855e3a88f74877738349948c78 : update Linux kernel when convenient.

Data as of 26 Oct 2026, 14:05 UTC

Severity

Unrated

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.2% chance of exploitation in 30 days – higher than 10% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in ae3e53fe3c1241855e3a88f74877738349948c78, ad72e2566643fff7f01666d845fb026898155e1f, 9a17b0e053197a6a42cdc75e75a35b17aa662088 +2

Exploitation evidence

Disclosed: evidence found.
CVE published 25 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 9ec52099e4b8678a60e9f93e41ad87885d64f3e6, < ae3e53fe3c1241855e3a88f74877738349948c78	Fixed in ae3e53fe3c1241855e3a88f74877738349948c78
LinuxLinux	Affected ≥ 9ec52099e4b8678a60e9f93e41ad87885d64f3e6, < ad72e2566643fff7f01666d845fb026898155e1f	Fixed in ad72e2566643fff7f01666d845fb026898155e1f
LinuxLinux	Affected ≥ 9ec52099e4b8678a60e9f93e41ad87885d64f3e6, < 9a17b0e053197a6a42cdc75e75a35b17aa662088	Fixed in 9a17b0e053197a6a42cdc75e75a35b17aa662088
LinuxLinux	Affected ≥ 9ec52099e4b8678a60e9f93e41ad87885d64f3e6, < 5a88f78df753993469dab4d1831f8fb4256a9468	Fixed in 5a88f78df753993469dab4d1831f8fb4256a9468
LinuxLinux	Affected ≥ 9ec52099e4b8678a60e9f93e41ad87885d64f3e6, < 0c1a966bc047af2801a70b8eb13f9df5d7ab925f	Fixed in 0c1a966bc047af2801a70b8eb13f9df5d7ab925f
LinuxLinux	Affected =2.6.19	Fixed in–

Description

In the Linux kernel, the following vulnerability has been resolved: reboot: fix cad_pid use-after-free race cad_pid is a single kernel-wide struct pid pointer. proc_do_cad_pid() reads it and passes it to pid_vnr() without protecting the lifetime of the referenced struct pid. A concurrent writer can replace cad_pid and drop the final reference to the old struct pid after the reader has loaded the pointer but before pid_vnr() has finished dereferencing it, causing a use-after-free. kill_cad_pid() has the same lifetime race when it passes cad_pid to kill_pid(). At the time this issue was reported, an unprivileged user could reach the sysctl through user and PID namespaces because cad_pid was registered in pid_table[]. Moving cad_pid back to the global reboot sysctl table corrected that namespace and permission mismatch, but did not fix the underlying lifetime race. Fix this by treating cad_pid as an RCU-protected pointer at both read sites and by waiting for a grace period before dropping the old reference on the write side. call_rcu(&old_pid->rcu, ...) cannot be used here because free_pid() also queues pid->rcu; queueing the same rcu_head twice can corrupt the RCU callback list. Original KASAN crash stack: kernel/pid.c:545 pid_nr_ns() # reads freed pid->level kernel/pid.c:556 pid_vnr() # calls pid_nr_ns() kernel/pid.c:775 proc_do_cad_pid() # calls pid_vnr(cad_pid)

References

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