Vulnary
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Critical· 9.8official fix available

CVE-2025-21707

This vulnerability affects the Linux kernel’s MultiPath TCP implementation, where uninitialized data can lead to memory corruption. It can cause the kernel to crash or allow attackers to gain elevated privileges. The flaw is critical because it can be triggered over the network without any user interaction.

publishedFeb 27, 2025
last modifiedJul 30, 2026
sourcesNVD
severity · cvss
9.8
critical · how bad it is
exploitation · epss
<1%
38th percentile · chance of exploitation in 30 days
(ai-assisted) A model wrote this summary from the official data, so double-check it against the source before you act on it. Read the official advisory →
auto-deletes from the system
counting…on Aug 29, 2026

An official fix is available, so this entry is kept for 30 days and then removed automatically.

01

Who is affected

Linux kernel, all versions before the patch that fixes the MPTCP suboption status handling. Typical users include Linux system administrators and any device or server that uses MPTCP.

02

Real-world impact

An attacker could send specially crafted MPTCP packets to a vulnerable system, potentially causing a kernel crash (denial of service) or exploiting memory corruption to gain higher privileges.

03

Why this severity

The CVSS score of 9.8 reflects that the flaw can be exploited remotely over the network, requires no privileges or user interaction, and can compromise confidentiality, integrity, and availability of the entire system.

04

What to do about it

official fix available
recommended steps
  1. 01Upgrade your Linux kernel to a version that includes the mptcp: consolidate suboption status patch.
  2. 02Reboot the system to load the updated kernel.

NVD description indicates the vulnerability has been resolved in the Linux kernel.

05

Timeline

  1. Feb 27, 2025 · Feb 27, 2025
    Published
    Disclosed and added to the National Vulnerability Database.
  2. Jul 30, 2026 · 7d ago
    Advisory updated
    The NVD record was last revised.
  3. Jul 30, 2026 · 6d ago
    Official fix available
    A vendor patch or mitigation now exists — see the remediation steps above.
06

How it’s attacked

Attack vectorNetwork (remote)
Attack complexityLow
Privileges requiredNone
User interactionNone needed
ScopeUnchanged
Confidentiality impactHigh
Integrity impactHigh
Availability impactHigh
07

References & advisories

NVD advisory ↗Search advisories ↗
(ai-assisted) A model wrote this summary from the official data, so double-check it against the source before you act on it. Read the official advisory →