high · 7.8

fbdev: hyperv_fb: Allow graceful removal of framebuffer

CVE-2025-21976 · published 1 Apr 2025

How serious is it

  • Severity: high, CVSS score 7.8 out of 10.
  • No exploit prediction (EPSS) score yet.
  • Not on the CISA list of exploited vulnerabilities.
  • No public exploit in Exploit-DB.

Is your app affected by CVE-2025-21976?

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Who is affected

  • Linux Linux: 68a2d20b79b105f02dcbc52c211d7e62f98996b7 to < b1a86a5ab0d44160534f495a3630646092d98e27, 68a2d20b79b105f02dcbc52c211d7e62f98996b7 to < 4545e2aa121aea304d33903099c03e29ed4fe50a, 68a2d20b79b105f02dcbc52c211d7e62f98996b7 to < a7b583dc99c6cf4a96877017be1d08247e1ef2c7, 68a2d20b79b105f02dcbc52c211d7e62f98996b7 to < ea2f45ab0e53b255f72c85ccd99e2b394fc5fceb
  • Linux Linux: 3.10

How to check

  1. Find out whether you run the affected product and which version, then compare it with the versions above.

How to fix

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  1. Apply the vendor's update or mitigation from the references below. If there is none yet, limit exposure of the affected service until there is.
  2. If a vulnerable version was live, check your logs and rotate the secrets that server could read.

The advisory

In the Linux kernel, the following vulnerability has been resolved: fbdev: hyperv_fb: Allow graceful removal of framebuffer When a Hyper-V framebuffer device is unbind, hyperv_fb driver tries to release the framebuffer forcefully. If this framebuffer is in use it produce the following WARN and hence this framebuffer is never released. [ 44.111220] WARNING: CPU: 35 PID: 1882 at drivers/video/fbdev/core/fb_info.c:70 framebuffer_release+0x2c/0x40 < snip > [ 44.111289] Call Trace: [ 44.111290] <TASK> [ 44.111291] ? show_regs+0x6c/0x80 [ 44.111295] ? __warn+0x8d/0x150 [ 44.111298] ? framebuffer_release+0x2c/0x40 [ 44.111300] ? report_bug+0x182/0x1b0 [ 44.111303] ? handle_bug+0x6e/0xb0 [ 44.111306] ? exc_invalid_op+0x18/0x80 [ 44.111308] ? asm_exc_invalid_op+0x1b/0x20 [ 44.111311] ? framebuffer_release+0x2c/0x40 [ 44.111313] ? hvfb_remove+0x86/0xa0 [hyperv_fb] [ 44.111315] vmbus_remove+0x24/0x40 [hv_vmbus] [ 44.111323] device_remove+0x40/0x80 [ 44.111325] device_release_driver_internal+0x20b/0x270 [ 44.111327] ? bus_find_device+0xb3/0xf0 Fix this by moving the release of framebuffer and assosiated memory to fb_ops.fb_destroy function, so that framebuffer framework handles it gracefully. While we fix this, also replace manual registrations/unregistration of framebuffer with devm_register_framebuffer.

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References

Merged from CVE List. Last updated 25 Oct 2026. All vulnerabilities · RSS · JSON

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