CVE-2021-47591

mptcp: remove tcp ulp setsockopt support

MEDIUM
5.5
CVSS Score
Published: June 19, 2024 at 02:53 PM UTC
Updated: June 17, 2026 at 04:17 AM UTC
1 product affected across 1 vendorLinux Kernel

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Severity
MEDIUM5.5
Exploit prediction
EPSS 0.2%
SSVC
No known exploit

Description

In the Linux kernel, the following vulnerability has been resolved: mptcp: remove tcp ulp setsockopt support TCP_ULP setsockopt cannot be used for mptcp because its already used internally to plumb subflow (tcp) sockets to the mptcp layer. syzbot managed to trigger a crash for mptcp connections that are in fallback mode: KASAN: null-ptr-deref in range [0x0000000000000020-0x0000000000000027] CPU: 1 PID: 1083 Comm: syz-executor.3 Not tainted 5.16.0-rc2-syzkaller #0 RIP: 0010:tls_build_proto net/tls/tls_main.c:776 [inline] [..] __tcp_set_ulp net/ipv4/tcp_ulp.c:139 [inline] tcp_set_ulp+0x428/0x4c0 net/ipv4/tcp_ulp.c:160 do_tcp_setsockopt+0x455/0x37c0 net/ipv4/tcp.c:3391 mptcp_setsockopt+0x1b47/0x2400 net/mptcp/sockopt.c:638 Remove support for TCP_ULP setsockopt.

Affected

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

5.13 ≤ v < 5.15.115.13 ≤ v < 5.165.16 rc15.16 rc25.16 rc35.16 rc45.16 rc5d9e4c129181004ec94b315b0c9db5eeb09da75e6
Vendor states this is fixed in 3de0c86d42f841d1d64f316cd949e65c566f0734 (fixed)
Vendor states this is fixed in 404cd9a22150f24acf23a8df2ad0c094ba379f57 (fixed)
Vendor states this is fixed in 5.13 (unaffected)
Vendor states this is fixed in 5.15.11 (unaffected)
Vendor states this is fixed in 5.16 (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/3de0c86d42f841d1d64f316cd949e65c566f0734
Patch
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/404cd9a22150f24acf23a8df2ad0c094ba379f57

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
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-476

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