high CVSS 7.8

CVE-2025-21680·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: pktgen: Avoid out-of-bounds access in get_imix_entries Passing a sufficient amount of imix entries leads to invalid access to the pkt_dev->imix_entries array because of the incorrect boundary check. UBSAN: array-index-out-of-bounds in net/core/pktgen.c:874:24 index 20 is out of range for type 'imix_pkt [20]' CPU: 2 PID: 1210 Comm: bash Not tainted 6.10.0-rc1 #121 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) Call Trace: <TASK> dump_stack_lvl lib/dump_stack.c:117 __ubsan_handle_out_of_bounds lib/ubsan.c:429 get_imix_entries net/core/pktgen.c:874 pktgen_if_write net/core/pktgen.c:1063 pde_write fs/proc/inode.c:334 proc_reg_write fs/proc/inode.c:346 vfs_write fs/read_write.c:593 ksys_write fs/read_write.c:644 do_syscall_64 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe arch/x86/entry/entry_64.S:130 Found by Linux Verification Center (linuxtesting.org) with SVACE. [ fp: allow to fill the array completely; minor changelog cleanup ]

Severity: high
Software: Kernel
Fixed in: 6.12.11
Published: 2025-01-31

Affected versions

From: 6.7

Until: 6.12.11

Fixed in: 6.12.11

How to fix this CVE

Update your Linux kernel to version 6.12.11 or later to patch an array boundary check flaw in the pktgen packet generator module. This vulnerability allows local users with low privileges to trigger out-of-bounds memory access. Apply the kernel update through your distribution's package manager and reboot your system to activate the patched kernel.

sudo dnf update kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

Step 1: Check your kernel version with `uname -r` and compare against the fixed version 6.12.11
Step 2: Verify pktgen module is loaded by running `lsmod | grep pktgen`
Step 3: Search kernel logs for UBSAN errors: `dmesg | grep -i 'ubsan\|out_of_bounds\|pktgen'` or `sudo journalctl -k | grep -i 'ubsan\|pktgen'`
Step 4: After applying the patch, confirm with `uname -r` that the new kernel version is active and the system has rebooted

FAQ

What is CVE-2025-21680?

CVE-2025-21680 is a kernel vulnerability in the pktgen module where an insufficient boundary check allows local attackers to access memory beyond the imix_entries array bounds, potentially causing privilege escalation or system instability.

Is CVE-2025-21680 being actively exploited?

No, there is no evidence of active exploitation in the wild. This vulnerability was discovered through automated analysis tools and is not listed in the CISA Known Exploited Vulnerabilities database.

What versions of Kernel are affected by CVE-2025-21680?

Linux kernel versions 6.7 through 6.12.10 are affected. The vulnerability is fixed in kernel 6.12.11 and later stable releases.

How do I check if my server is vulnerable to CVE-2025-21680?

Run `uname -r` and check if your kernel version is between 6.7 and 6.12.10. If the output shows a vulnerable version in this range, your system requires patching.

Does Defensia detect CVE-2025-21680?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If the Linux kernel is installed on a monitored server, CVE-2025-21680 will appear in your dashboard with remediation steps.

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References

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