fbdev: vfb: defer cleanup until the last reference (CVE-2026-97604) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-97604

fbdev: vfb: defer cleanup until the last reference

Answer in brief

CVE-2026-97604 records a Unknown severity vulnerability in fbdev: vfb: defer cleanup until the last reference. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 25, 2026Updated Sep 25, 2026Source checked Sep 25, 2026First seen by HOL Sep 25, 2026Material review Sep 25, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Linux/Linuxgeneric	>=5e266e2e0e19532c1b8e2e2bff1eb6ccf42e478a <86356f13598f59f5acb1754895747dcdaf65a254 \|\| >=5e266e2e0e19532c1b8e2e2bff1eb6ccf42e478a <5ff1effb047e465cde193d7df95988aa1520035e \|\| >=5e266e2e0e19532c1b8e2e2bff1eb6ccf42e478a <3c91e51a53cf805e551e5dc8149cd0539a6dbb9d \|\| >=5e266e2e0e19532c1b8e2e2bff1eb6ccf42e478a <a0a34a40ed299c9c7cff6af163a5b883ee9d6d73	86356f13598f59f5acb1754895747dcdaf65a254, 5ff1effb047e465cde193d7df95988aa1520035e, 3c91e51a53cf805e551e5dc8149cd0539a6dbb9d, a0a34a40ed299c9c7cff6af163a5b883ee9d6d73
Linux/Linuxgeneric	2.6.30	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to 86356f13598f59f5acb1754895747dcdaf65a254 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 25, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 25, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 25, 2026

Sources and claim methodology

Upstream source description

In the Linux kernel, the following vulnerability has been resolved: fbdev: vfb: defer cleanup until the last reference FBIOGETCMAP takes a shallow snapshot of info->cmap and performs the usercopy after dropping info->lock. vfb_remove() frees the colormap immediately after unregistering the framebuffer, even when an open file still holds a reference to fb_info. A concurrent driver unbind can therefore free the colormap while the ioctl copies it to userspace. KASAN reports: BUG: KASAN: slab-use-after-free in _copy_to_user Read of size 512 by task poc/125 _copy_to_user (./include/linux/instrumented.h:129 ./include/linux/uaccess.h:201 lib/usercopy.c:24) fb_cmap_to_user (./include/linux/uaccess.h:230 drivers/video/fbdev/core/fbcmap.c:211) do_fb_ioctl (drivers/video/fbdev/core/fb_chrdev.c:114) Allocated by task 1: fb_alloc_cmap_gfp (./include/linux/slab.h:973 ./include/linux/slab.h:1290 drivers/video/fbdev/core/fbcmap.c:108) vfb_probe (drivers/video/fbdev/vfb.c:459) Freed by task 124: fb_dealloc_cmap (drivers/video/fbdev/core/fbcmap.c:151) vfb_remove (drivers/video/fbdev/vfb.c:489) unregister_framebuffer() drops the registration reference, and fbdev calls fb_destroy after the last put_fb_info(). Move the registered framebuffer's cleanup into an fb_destroy callback so its colormap and screen buffer stay alive until all file references have been released.

Quoted source text, attributed separately from HOL analysis.