CVE-2021-47132

mptcp: fix sk_forward_memory corruption on retransmission

HIGH
7.1
CVSS Score
Published: March 15, 2024 at 08:14 PM UTC
Updated: August 5, 2026 at 09:24 AM UTC
1 product affected across 1 vendorLinux Kernel

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Severity
HIGH7.1
Exploit prediction
EPSS 0.5%
SSVC
No known exploit

Description

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v ≥ 5.11.45.11.4 ≤ v < 5.125.12 ≤ v < 5.12.105.12 ≤ v < 5.135.11.45.13 rc15.13 rc25.13 rc35.13 rc464b9cea7a0afe579dd2682f1f1c04f2e4e72fd2596db8ffef07516a6d7414b6988f2a4298a839977
Vendor states this is fixed in b5941f066b4ca331db225a976dae1d6ca8cf0ae3 (fixed)
Vendor states this is fixed in b9c78b1a95966a7bd2ddae05b73eafc0cda4fba3 (fixed)
Vendor states this is fixed in 5.12 (unaffected)
Vendor states this is fixed in 5.12.10 (unaffected)
Vendor states this is fixed in 5.13 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (2)

Patch
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/b5941f066b4ca331db225a976dae1d6ca8cf0ae3
Patch
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/b9c78b1a95966a7bd2ddae05b73eafc0cda4fba3

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
LOCAL
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-787

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