high CVSS 7.8

CVE-2025-21687·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: vfio/platform: check the bounds of read/write syscalls count and offset are passed from user space and not checked, only offset is capped to 40 bits, which can be used to read/write out of bounds of the device.

Severity
high
Software
Kernel
Fixed in
6.12.12
Published
2025-02-10

Affected versions

From: 6.7

Until: 6.12.12

Fixed in: 6.12.12

How to fix this CVE

Update your Linux kernel to version 6.12.12 or later to patch a bounds-checking vulnerability in the VFIO platform driver that could allow local privilege escalation. This vulnerability affects kernel versions 6.7 through 6.12.11 and requires immediate patching to prevent out-of-bounds memory access through userspace read/write operations.

sudo dnf update kernel kernel-headers

Defensia detects this vulnerability

How to check if you are affected

  1. Step 1: Check the current kernel version with `uname -r` and compare against the affected range (6.7 to 6.12.11)
  2. Step 2: Verify VFIO platform driver is loaded with `lsmod | grep vfio_platform` — if present, the system may be vulnerable
  3. Step 3: Search kernel logs for memory access errors near VFIO operations using `journalctl -u kernel | grep -i 'vfio\|bounds\|out of bounds' | tail -50`
  4. Step 4: After updating, confirm the new kernel version with `uname -r` and reboot if necessary with `sudo reboot`

FAQ

What is CVE-2025-21687?

CVE-2025-21687 is a bounds-checking vulnerability in the Linux kernel's VFIO platform driver that fails to properly validate the size and offset of read/write operations from userspace, allowing a local attacker to access memory beyond device boundaries.

Is CVE-2025-21687 being actively exploited?

No, CVE-2025-21687 is not currently listed in CISA's Known Exploited Vulnerabilities catalog, and no public exploit code is available.

What versions of Kernel are affected by CVE-2025-21687?

Linux kernel versions 6.7 through 6.12.11 are vulnerable. Kernel 6.12.12 and later versions include the fix.

How do I check if my server is vulnerable to CVE-2025-21687?

Run `uname -r` to display your kernel version. If it falls between 6.7 and 6.12.11, and `lsmod | grep vfio_platform` shows the driver is loaded, your system is vulnerable.

Does Defensia detect CVE-2025-21687?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Kernel is installed on a monitored server, CVE-2025-21687 will appear in your dashboard with remediation steps.

Related Kernel CVEs

CVE-2024-42256CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: cifs: Fix server re-repick on subrequest retry When a subrequest is marked for needing retry, netfs will call cifs_prepare_write() which will make cifs repick the server for the op before renegotiating credits; it then calls cifs_issue_write() which invokes smb2_async_writev() - which re-repicks the server. If a different server is then selected, this causes the increment of server->in_flight to happen against one record and the decrement to happen against another, leading to misaccounting. Fix this by just removing the repick code in smb2_async_writev(). As this is only called from netfslib-driven code, cifs_prepare_write() should always have been called first, and so server should never be NULL and the preparatory step is repeated in the event that we do a retry. The problem manifests as a warning looking something like: WARNING: CPU: 4 PID: 72896 at fs/smb/client/smb2ops.c:97 smb2_add_credits+0x3f0/0x9e0 [cifs] ... RIP: 0010:smb2_add_credits+0x3f0/0x9e0 [cifs] ... smb2_writev_callback+0x334/0x560 [cifs] cifs_demultiplex_thread+0x77a/0x11b0 [cifs] kthread+0x187/0x1d0 ret_from_fork+0x34/0x60 ret_from_fork_asm+0x1a/0x30 Which may be triggered by a number of different xfstests running against an Azure server in multichannel mode. generic/249 seems the most repeatable, but generic/215, generic/249 and generic/308 may also show it.
CVE-2024-36031CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: keys: Fix overwrite of key expiration on instantiation The expiry time of a key is unconditionally overwritten during instantiation, defaulting to turn it permanent. This causes a problem for DNS resolution as the expiration set by user-space is overwritten to TIME64_MAX, disabling further DNS updates. Fix this by restoring the condition that key_set_expiry is only called when the pre-parser sets a specific expiry.
CVE-2024-38612CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: ipv6: sr: fix invalid unregister error path The error path of seg6_init() is wrong in case CONFIG_IPV6_SEG6_LWTUNNEL is not defined. In that case if seg6_hmac_init() fails, the genl_unregister_family() isn't called. This issue exist since commit 46738b1317e1 ("ipv6: sr: add option to control lwtunnel support"), and commit 5559cea2d5aa ("ipv6: sr: fix possible use-after-free and null-ptr-deref") replaced unregister_pernet_subsys() with genl_unregister_family() in this error path.
CVE-2024-38623CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: fs/ntfs3: Use variable length array instead of fixed size Should fix smatch warning: ntfs_set_label() error: __builtin_memcpy() 'uni->name' too small (20 vs 256)
CVE-2021-47548CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: ethernet: hisilicon: hns: hns_dsaf_misc: fix a possible array overflow in hns_dsaf_ge_srst_by_port() The if statement: if (port >= DSAF_GE_NUM) return; limits the value of port less than DSAF_GE_NUM (i.e., 8). However, if the value of port is 6 or 7, an array overflow could occur: port_rst_off = dsaf_dev->mac_cb[port]->port_rst_off; because the length of dsaf_dev->mac_cb is DSAF_MAX_PORT_NUM (i.e., 6). To fix this possible array overflow, we first check port and if it is greater than or equal to DSAF_MAX_PORT_NUM, the function returns.

References

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