VulnerabilityPublished 18 Oct 2026Updated 21 Oct 2026

CVE-2026-98840: Linux kernel · vc_screen: reload vc pointer before if (ret) in vcs_write() to avoid UAF

Source GCVE Database

Authoritative record:CVE-2026-98840

Not known to be exploited · fixed in c073d01f6f5367c3a4f07efd507274ed0d03acd0 : update Linux kernel when convenient.

Data as of 26 Oct 2026, 14:05 UTC

Severity

Medium

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.1% chance of exploitation in 30 days – higher than 5% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in c073d01f6f5367c3a4f07efd507274ed0d03acd0, 1485a3dd97ab1af2605243cabe6b604546d46dd1, 233a2e190b12884d186027d0b86d43a48799b69c +10

Exploitation evidence

Disclosed: evidence found.
CVE published 18 Oct 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.

ghsa-vpw3-5qwq-wxvw

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected >=6.6.144 <6.6.160 >=6.12.95 <6.12.113 >=6.18.37 <6.18.56 >=5.10.260 <5.11 >=5.15.211 <5.16 >=6.1.177 <6.2 >=7.0.14 <7.1 >=7.1.2 <7.2	Fixed in c073d01f6f5367c3a4f07efd507274ed0d03acd0 1485a3dd97ab1af2605243cabe6b604546d46dd1 233a2e190b12884d186027d0b86d43a48799b69c 226bd5603371cd9f6642cbb9e9a677f445de3530 9dfcadc5e003fb250dd471db90144bd5366140e9 7.2 7.1 6.18.56 6.12.113 6.6.160 6.2 5.16 5.11
LinuxLinux	Affected =7.2	Fixed in–

AI-suggested

A fix has been implemented in the Linux kernel by moving the reload of the vc pointer to before the 'if (ret)' check in vcs_write(). Users should update to a Linux kernel version that includes this fix. Patch status is not explicitly confirmed in the provided data; check the vendor or Linux kernel advisory for the exact fixed versions and update accordingly.

Description

A use-after-free (UAF) vulnerability in the Linux kernel's vc_screen component was resolved by reloading the vc pointer before checking the return value in the vcs_write() function. The issue occurred because the vc pointer could become stale and non-NULL after being freed, leading to a read from freed memory in vcs_notifier(). This could cause kernel memory corruption and crashes.

Impact

This vulnerability can lead to use-after-free memory access in the kernel, potentially causing kernel crashes or memory corruption. There is no indication of remote exploitability or privilege escalation in the provided data. The impact is limited to kernel stability and memory safety.

Summary

The vulnerability in the Linux kernel's vc_screen subsystem involves a use-after-free condition in the vcs_write() function. The reload of the vc pointer was originally placed after an 'if (ret)' block, which allowed a stale non-NULL vc pointer to be used if the vc was freed during an unlocked copy_from_user() window. This stale pointer was then dereferenced in vcs_notifier(), causing a slab-use-after-free error detected by KASAN. The fix moves the reload of the vc pointer to immediately after console_lock(), before the 'if (ret)' check, ensuring that all code paths use a fresh vc pointer and preventing use-after-free.

References

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