Linux Kernel up to 5.12.9 mptcp __mptcp_retrans memory corruption

Summaryinfo

A vulnerability described as critical has been identified in Linux Kernel up to 5.12.9. This impacts the function __mptcp_retrans of the component mptcp. Such manipulation leads to memory corruption. This vulnerability is traded as CVE-2021-47132. There is no exploit available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Linux Kernel up to 5.12.9. Affected by this issue is the function __mptcp_retrans of the component mptcp. The manipulation with an unknown input leads to a memory corruption vulnerability. Using CWE to declare the problem leads to CWE-119. The product performs operations on a memory buffer, but it can read from or write to a memory location that is outside of the intended boundary of the buffer. Impacted is confidentiality, integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: mptcp: fix sk_forward_memory corruption on retransmission MPTCP sk_forward_memory handling is a bit special, as such field is protected by the msk socket spin_lock, instead of the plain socket lock. Currently we have a code path updating such field without handling the relevant lock: __mptcp_retrans() -> __mptcp_clean_una_wakeup() Several helpers in __mptcp_clean_una_wakeup() will update sk_forward_alloc, possibly causing such field corruption, as reported by Matthieu. Address the issue providing and using a new variant of blamed function which explicitly acquires the msk spin lock.

The advisory is shared for download at git.kernel.org. This vulnerability is handled as CVE-2021-47132 since 03/04/2024. The exploitation is known to be easy. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 03/13/2025).

Upgrading to version 5.12.10 or 5.13 eliminates this vulnerability. Applying the patch b9c78b1a9596/b5941f066b4c is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 5.12.0
• 5.12.1
• 5.12.2
• 5.12.3
• 5.12.4
• 5.12.5
• 5.12.6
• 5.12.7
• 5.12.8
• 5.12.9

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

• 🔍
• 🔍
• 🔍

CPE 2.2info

• 🔍
• 🔍
• 🔍

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

VulDB is the best source for vulnerability data and more expert information about this specific topic.

Discussion