CVE-2025-21653
5.5 · MEDIUMOverview
CVE-2025-21653 is a medium-severity vulnerability affecting linux linux_kernel. It was published on January 19, 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:
net_sched: cls_flow: validate TCA_FLOW_RSHIFT attribute
syzbot found that TCA_FLOW_RSHIFT attribute was not validated.
Right shitfing a 32bit integer is undefined for large shift values.
UBSAN: shift-out-of-bounds in net/sched/cls_flow.c:329:23
shift exponent 9445 is too large for 32-bit type 'u32' (aka 'unsigned int')
CPU: 1 UID: 0 PID: 54 Comm: kworker/u8:3 Not tainted 6.13.0-rc3-syzkaller-00180-g4f619d518db9 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Workqueue: ipv6_addrconf addrconf_dad_work
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
ubsan_epilogue lib/ubsan.c:231 [inline]
__ubsan_handle_shift_out_of_bounds+0x3c8/0x420 lib/ubsan.c:468
flow_classify+0x24d5/0x25b0 net/sched/cls_flow.c:329
tc_classify include/net/tc_wrapper.h:197 [inline]
__tcf_classify net/sched/cls_api.c:1771 [inline]
Remediation
Check the references section for vendor advisories and patches from linux. Update linux_kernel to the latest patched version. 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.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| linux | linux_kernel | >= 2.6.25, < 5.4.290 | Affected |
References
Frequently Asked Questions
What is CVE-2025-21653?
CVE-2025-21653 is a medium-severity vulnerability affecting linux linux_kernel. It was published on January 19, 2025 and has a CVSS 3.1 base score of 5.5 (MEDIUM).
How severe is CVE-2025-21653?
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-2025-21653?
Check the references section for vendor advisories and patches from linux. Update linux_kernel to the latest patched version. 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-2025-21653?
CyberStrike's AI-powered security agents can automatically detect CVE-2025-21653 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
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