CVE-2021-47242

HIGHNVD 7.87.8—
EchelonGraph scoreMEDIUM confidence

Score 7.8 from GitHub Security Advisory (severity: HIGH) published 2024-05-21. NVD baseline CVSS 7.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
7.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 7.8Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

In the Linux kernel, the following vulnerability has been resolved:

mptcp: fix soft lookup in subflow_error_report()

Maxim reported a soft lookup in subflow_error_report():

watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [swapper/0:0] RIP: 0010:native_queued_spin_lock_slowpath RSP: 0018:ffffa859c0003bc0 EFLAGS: 00000202 RAX: 0000000000000101 RBX: 0000000000000001 RCX: 0000000000000000 RDX: ffff9195c2772d88 RSI: 0000000000000000 RDI: ffff9195c2772d88 RBP: ffff9195c2772d00 R08: 00000000000067b0 R09: c6e31da9eb1e44f4 R10: ffff9195ef379700 R11: ffff9195edb50710 R12: ffff9195c2772d88 R13: ffff9195f500e3d0 R14: ffff9195ef379700 R15: ffff9195ef379700 FS: 0000000000000000(0000) GS:ffff91961f400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000c000407000 CR3: 0000000002988000 CR4: 00000000000006f0 Call Trace: _raw_spin_lock_bh subflow_error_report mptcp_subflow_data_available __mptcp_move_skbs_from_subflow mptcp_data_ready tcp_data_queue tcp_rcv_established tcp_v4_do_rcv tcp_v4_rcv ip_protocol_deliver_rcu ip_local_deliver_finish __netif_receive_skb_one_core netif_receive_skb rtl8139_poll 8139too __napi_poll net_rx_action __do_softirq __irq_exit_rcu common_interrupt

The calling function - mptcp_subflow_data_available() - can be invoked from different contexts:

  • plain ssk socket lock
  • ssk socket lock + mptcp_data_lock
  • ssk socket lock + mptcp_data_lock + msk socket lock.

Since subflow_error_report() tries to acquire the mptcp_data_lock, the latter two call chains will cause soft lookup.

This change addresses the issue moving the error reporting call to outer functions, where the held locks list is known and the we can acquire only the needed one.

CVSS v3
7.8
EG Score
7.8(medium)
EPSS
8.5%
KEV
Not listed

Published

May 21, 2024

Last Modified

April 4, 2025

References (4)

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 10× in last 7d / 45× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-11 08:25 UTCEPSS rescore
  2. 2026-07-09 19:07 UTCEPSS rescore
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  4. 2026-07-08 15:12 UTCEPSS rescore
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  16. 2026-06-29 14:04 UTCEPSS rescore
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  21. 2026-06-27 03:07 UTCEPSS rescore
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  23. 2026-06-25 13:48 UTCEPSS rescore
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  25. 2026-06-24 14:03 UTCEPSS rescore
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  1. 2026-06-24 14:03 UTCEPSS rescore
  2. 2026-06-23 21:31 UTCEPSS rescore
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  4. 2026-06-22 14:24 UTCEPSS rescore
  5. 2026-06-21 14:55 UTCEPSS rescore
  6. 2026-06-21 01:58 UTCEPSS rescore
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  8. 2026-06-19 19:24 UTCEPSS rescore
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  10. 2026-06-18 17:51 UTCEPSS rescore
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  18. 2026-06-13 22:58 UTCEPSS rescore
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  20. 2026-06-12 23:10 UTCEPSS rescore
  21. 2026-06-11 13:58 UTCEPSS rescore
  22. 2026-06-10 22:16 UTCEPSS rescore
  23. 2026-06-10 13:20 UTCEPSS rescore
  24. 2026-06-08 14:15 UTCEPSS rescore
  25. 2026-06-08 14:15 UTCEPSS rescore
  26. 2026-06-08 14:15 UTCEPSS rescore
  27. 2026-06-07 15:23 UTCEPSS rescore
  28. 2026-06-07 15:23 UTCEPSS rescore
  29. 2026-06-06 13:46 UTCEPSS rescore
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  31. 2026-06-05 22:45 UTCEPSS rescore
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  37. 2026-06-02 20:11 UTCEPSS rescore
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  39. 2026-06-01 13:50 UTCEPSS rescore
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  41. 2026-05-31 22:29 UTCEPSS rescore
  42. 2026-05-31 00:15 UTCEPSS rescore
  43. 2026-05-31 00:15 UTCEPSS rescore
  44. 2026-05-29 13:42 UTCEPSS rescore
  45. 2026-05-28 13:43 UTCEPSS rescore
  46. 2026-05-28 13:43 UTCEPSS rescore
  47. 2026-05-27 13:39 UTCEPSS rescore
  48. 2026-05-27 13:39 UTCEPSS rescore
  49. 2026-05-26 13:43 UTCEPSS rescore
  50. 2026-05-26 13:42 UTCEPSS rescore
  51. 2026-05-26 07:17 UTCEPSS rescore
  52. 2026-05-26 07:17 UTCEPSS rescore
  53. 2026-05-24 01:38 UTCEG score recompute
  54. 2026-05-24 01:38 UTCGHSA enrichment

Frequently asked(5)

What is CVE-2021-47242?
CVE-2021-47242 is a high vulnerability published on May 21, 2024. In the Linux kernel, the following vulnerability has been resolved: mptcp: fix soft lookup in subflowerrorreport() Maxim reported a soft lookup in subflowerrorreport(): watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [swapper/0:0] RIP: 0010:nativequeuedspinlockslowpath RSP: 0018:ffffa859c0003bc0…
When was CVE-2021-47242 disclosed?
CVE-2021-47242 was first published in the National Vulnerability Database on May 21, 2024, with the most recent update on April 4, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-47242 actively exploited?
CVE-2021-47242 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 8.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-47242?
CVE-2021-47242 has a CVSS v3 base score of 7.8 (NVD).
How do I remediate CVE-2021-47242?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-47242, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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