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NVD / CVE Program· CNA Linux

CVE-2025-68227: mptcp: Fix proto fallback detection with BPF

Noroxi assessment

Priority: Monitor (action score 0/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.21% (FIRST EPSS).
  • Fixed version: Linux Linux 037cc50589643342d69185b663ecf9d26cce91e8, 1a0d5c74af9b6ba9ffdf1172de5a1a6df5922a00, 344974ea1a3ca30e4920687b0091bda4438cebdb.

Low priority for now. Upgrade to Linux Linux 037cc50589643342d69185b663ecf9d26cce91e8, 1a0d5c74af9b6ba9ffdf1172de5a1a6df5922a00, 344974ea1a3ca30e4920687b0091bda4438cebdb or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: mptcp: Fix proto fallback detection with BPF The sockmap feature allows bpf syscall from userspace, or based on bpf sockops, replacing the sk_prot of sockets during protocol stack processing with sockmap's custom read/write interfaces. ''' tcp_rcv_state_process() syn_recv_sock()/subflow_syn_recv_sock() tcp_init_transfer(BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB) bpf_skops_established <== sockops bpf_sock_map_update(sk) <== call bpf helper tcp_bpf_update_proto() <== update sk_prot ''' When the server has MPTCP enabled but the client sends a TCP SYN without MPTCP, subflow_syn_recv_sock() performs a fallback on the subflow, replacing the subflow sk's sk_prot with the native sk_prot. ''' subflow_syn_recv_sock() subflow_ulp_fallback() subflow_drop_ctx() mptcp_subflow_ops_undo_override() ''' Then, this subflow can be normally used by sockmap, which replaces the native sk_prot with sockmap's custom sk_prot. The issue occurs when the user executes accept::mptcp_stream_accept::mptcp_fallback_tcp_ops(). Here, it uses sk->sk_prot to compare with the native sk_prot, but this is incorrect when sockmap is used, as we may incorrectly set sk->sk_socket->ops. This fix uses the more generic sk_family for the comparison instead. Additionally, this also prevents a WARNING from occurring: result from ./scripts/decode_stacktrace.sh: ------------[ cut here ]------------ WARNING: CPU: 0 PID: 337 at net/mptcp/protocol.c:68 mptcp_stream_accept \ (net/mptcp/protocol.c:4005) Modules linked in: ... PKRU: 55555554 Call Trace: <TASK> do_accept (net/socket.c:1989) __sys_accept4 (net/socket.c:2028 net/socket.c:2057) __x64_sys_accept (net/socket.c:2067) x64_sys_call (arch/x86/entry/syscall_64.c:41) do_syscall_64 (arch/x86/entry/syscall_64.c:63 arch/x86/entry/syscall_64.c:94) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) RIP: 0033:0x7f87ac92b83d ---[ end trace 0000000000000000 ]---

—No exploit Fix available
Published
Dec 16, 2025
Updated
Oct 14, 2026
EPSS
0.2% · 12th percentile
CWE
—

Report tools

JSON

Action score

0

Monitor

Low priority for now.

CVSS
0 / 40 · —
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

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Noroxi analysis

What does it mean in your environment?

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 5.7affected
    • 0b4f33def7bbde1ce2fea05f116639270e7acdc7 and later · before 92c4092fe012ecdfa5fb05d394f1c1d8f91ad81caffected · git
    • 0b4f33def7bbde1ce2fea05f116639270e7acdc7 and later · before 7ee8f015eb47907745e2070184a8ab1e442ac3c4affected · git
    • 0b4f33def7bbde1ce2fea05f116639270e7acdc7 and later · before 344974ea1a3ca30e4920687b0091bda4438cebdbaffected · git
    • 0b4f33def7bbde1ce2fea05f116639270e7acdc7 and later · before 037cc50589643342d69185b663ecf9d26cce91e8affected · git
    • 0b4f33def7bbde1ce2fea05f116639270e7acdc7 and later · before 9b1980b6f23fa30bf12add19f37c7458625099ebaffected · git
    • 0b4f33def7bbde1ce2fea05f116639270e7acdc7 and later · before 1a0d5c74af9b6ba9ffdf1172de5a1a6df5922a00affected · git
    • 0b4f33def7bbde1ce2fea05f116639270e7acdc7 and later · before c77b3b79a92e3345aa1ee296180d1af4e7031f8faffected · git
    • before 5.7not affected · semver
    • 5.10.247 and later · up to and including 5.10.*not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.159-16.1.159-1
Debian:13linuxbefore 6.12.63-16.12.63-1
Debian:14linuxbefore 6.17.10-16.17.10-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2025-68225Dec 16, 2025 · lib/test_kho: check if KHO is enabled
    0Monitor
  • ← EarlierCVE-2025-68226Dec 16, 2025 · smb: client: fix incomplete backport in cfids_invalidation_worker()
    35Monitor
  • Later →CVE-2025-68228Dec 16, 2025 · drm/plane: Fix create_in_format_blob() return value
    0Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux037cc50589643342d69185b663ecf9d26cce91e8Vendor (CNA)
Linux Linux1a0d5c74af9b6ba9ffdf1172de5a1a6df5922a00Vendor (CNA)
Linux Linux344974ea1a3ca30e4920687b0091bda4438cebdbVendor (CNA)
Linux Linux7ee8f015eb47907745e2070184a8ab1e442ac3c4Vendor (CNA)
Linux Linux92c4092fe012ecdfa5fb05d394f1c1d8f91ad81cVendor (CNA)
Linux Linux9b1980b6f23fa30bf12add19f37c7458625099ebVendor (CNA)
Linux Linuxc77b3b79a92e3345aa1ee296180d1af4e7031f8fVendor (CNA)
debian:linux6.1.159-1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

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No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

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Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

No CVSS vector for this record, so attack conditions can't be derived.

Weakness class (CWE)

—

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

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References

Show all references (6 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

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