CVE-2025-21707
9.8 · CRITICALOverview
CVE-2025-21707 is a critical-severity vulnerability affecting linux linux_kernel. It was published on February 27, 2025 and has a CVSS 3.1 base score of 9.8 (CRITICAL).
This vulnerability has a CVSS 3.1 base score of 9.8, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical Description
In the Linux kernel, the following vulnerability has been resolved:
mptcp: consolidate suboption status
MPTCP maintains the received sub-options status is the bitmask carrying
the received suboptions and in several bitfields carrying per suboption
additional info.
Zeroing the bitmask before parsing is not enough to ensure a consistent
status, and the MPTCP code has to additionally clear some bitfiled
depending on the actually parsed suboption.
The above schema is fragile, and syzbot managed to trigger a path where
a relevant bitfield is not cleared/initialized:
BUG: KMSAN: uninit-value in __mptcp_expand_seq net/mptcp/options.c:1030 [inline]
BUG: KMSAN: uninit-value in mptcp_expand_seq net/mptcp/protocol.h:864 [inline]
BUG: KMSAN: uninit-value in ack_update_msk net/mptcp/options.c:1060 [inline]
BUG: KMSAN: uninit-value in mptcp_incoming_options+0x2036/0x3d30 net/mptcp/options.c:1209
__mptcp_expand_seq net/mptcp/options.c:1030 [inline]
mptcp_expand_seq net/mptcp/protoc
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 | >= 5.11, < 6.1.129 | Affected |
References
Frequently Asked Questions
What is CVE-2025-21707?
CVE-2025-21707 is a critical-severity vulnerability affecting linux linux_kernel. It was published on February 27, 2025 and has a CVSS 3.1 base score of 9.8 (CRITICAL).
How severe is CVE-2025-21707?
This vulnerability has a CVSS 3.1 base score of 9.8, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2025-21707?
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-2025-21707?
CyberStrike's AI-powered security agents can automatically detect CVE-2025-21707 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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