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CVE-2025-21881

5.5 · MEDIUM

In the Linux kernel, the following vulnerability has been resolved: uprobes: Reject the shared zeropage in uprobe_write_opcode() We triggered the following crash in syzkaller tests: BUG: Bad p…

Published Mar 27, 2025EPSS 0.21%

Overview

CVE-2025-21881 is a medium-severity vulnerability. It was published on March 27, 2025 and has a CVSS 3.1 base score of 5.5 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 5.5, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

Technical description

In the Linux kernel, the following vulnerability has been resolved:

uprobes: Reject the shared zeropage in uprobe_write_opcode()

We triggered the following crash in syzkaller tests:

BUG: Bad page state in process syz.7.38 pfn:1eff3

page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1eff3

flags: 0x3fffff00004004(referenced|reserved|node=0|zone=1|lastcpupid=0x1fffff)

raw: 003fffff00004004 ffffe6c6c07bfcc8 ffffe6c6c07bfcc8 0000000000000000

raw: 0000000000000000 0000000000000000 00000000fffffffe 0000000000000000

page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set

Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014

Call Trace:

<TASK>

dump_stack_lvl+0x32/0x50

bad_page+0x69/0xf0

free_unref_page_prepare+0x401/0x500

free_unref_page+0x6d/0x1b0

uprobe_write_opcode+0x460/0x8e0

install_breakpoint.part.0+0x51/0x80

register_for_each_vma+0x1d9/0x2b0

__uprobe_register+0x245/0x300

bpf_uprobe_mu

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refgit.kernel.org/stable/c/0b6f19714588cf2366b0364234f97ba963688f63Refgit.kernel.org/stable/c/13cca2b73e2b0ec3ea6d6615d615395621d22752Refgit.kernel.org/stable/c/54011fc94422f094eaf47555284de70a4bc32bb9Refgit.kernel.org/stable/c/bddf10d26e6e5114e7415a0e442ec6f51a559468Refgit.kernel.org/stable/c/c4cb2bfa99513311886c1eb5c1c2ac26f3338a6eReflists.debian.org/debian-lts-announce/2025/05/msg00045.html

How CyberStrike helps

Frequently asked questions

What is CVE-2025-21881?

CVE-2025-21881 is a medium-severity vulnerability. It was published on March 27, 2025 and has a CVSS 3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2025-21881?

This vulnerability has a CVSS 3.1 base score of 5.5, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2025-21881?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2025-21881?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2025-21881 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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