In the Linux kernel, the following vulnerability has been resolved:
vc_screen: fix null-ptr-deref in vcs_notifier() during concurrent vcs_write
A KASAN null-ptr-deref was observed in vcs_notifier():
BUG: KASAN: null-ptr-deref in vcs_notifier+0x98/0x130
Read of size 2 at addr qmp_cmd_name: qmp_capabilities, arguments: {}
The issue is a race condition in vcs_write(). When the console_lock is
temporarily dropped (to copy data from userspace), the vc_data pointer
obtained from vcs_vc() may become stale. After re-acquiring the lock,
vcs_vc() is called again to re-validate the pointer. If the vc has been
deallocated in the meantime, vcs_vc() returns NULL, and the while loop
breaks (with written > 0). However, after the loop, vcs_scr_updated(vc)
is still called with the now-NULL vc pointer, leading to a null pointer
dereference in the notifier chain (vcs_notifier dereferences param->vc).
Fix this by adding a NULL check for vc before calling vcs_scr_updated().
vc_screen: fix null-ptr-deref in vcs_notifier() during concurrent vcs_write
A KASAN null-ptr-deref was observed in vcs_notifier():
BUG: KASAN: null-ptr-deref in vcs_notifier+0x98/0x130
Read of size 2 at addr qmp_cmd_name: qmp_capabilities, arguments: {}
The issue is a race condition in vcs_write(). When the console_lock is
temporarily dropped (to copy data from userspace), the vc_data pointer
obtained from vcs_vc() may become stale. After re-acquiring the lock,
vcs_vc() is called again to re-validate the pointer. If the vc has been
deallocated in the meantime, vcs_vc() returns NULL, and the while loop
breaks (with written > 0). However, after the loop, vcs_scr_updated(vc)
is still called with the now-NULL vc pointer, leading to a null pointer
dereference in the notifier chain (vcs_notifier dereferences param->vc).
Fix this by adding a NULL check for vc before calling vcs_scr_updated().
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
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| Linux | Linux | unaffected |
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| Linux | Linux | affected |
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Linux Kernel
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Fixes
Solution
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Workaround
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References
History
Tue, 21 Jul 2026 00:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-476 | |
| References |
| |
| Metrics |
threat_severity
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cvssV3_1
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Sun, 19 Jul 2026 12:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: vc_screen: fix null-ptr-deref in vcs_notifier() during concurrent vcs_write A KASAN null-ptr-deref was observed in vcs_notifier(): BUG: KASAN: null-ptr-deref in vcs_notifier+0x98/0x130 Read of size 2 at addr qmp_cmd_name: qmp_capabilities, arguments: {} The issue is a race condition in vcs_write(). When the console_lock is temporarily dropped (to copy data from userspace), the vc_data pointer obtained from vcs_vc() may become stale. After re-acquiring the lock, vcs_vc() is called again to re-validate the pointer. If the vc has been deallocated in the meantime, vcs_vc() returns NULL, and the while loop breaks (with written > 0). However, after the loop, vcs_scr_updated(vc) is still called with the now-NULL vc pointer, leading to a null pointer dereference in the notifier chain (vcs_notifier dereferences param->vc). Fix this by adding a NULL check for vc before calling vcs_scr_updated(). | |
| Title | vc_screen: fix null-ptr-deref in vcs_notifier() during concurrent vcs_write | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
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Projects
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-07-19T11:59:32.732Z
Reserved: 2026-06-09T07:44:35.401Z
Link: CVE-2026-53385
Vulnrichment
No data.
NVD
No data.
Redhat
OpenCVE Enrichment
Updated: 2026-07-21T12:30:03Z
Weaknesses