CVE-2025-21705

MEDIUMNVD 5.55.5—
EchelonGraph scoreMEDIUM confidence

Score 5.5 from GitHub Security Advisory published 2025-02-27. NVD baseline CVSS 5.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
5.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.5Exploit: None knownExposed: 0

A fix is available — apply it.

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

mptcp: handle fastopen disconnect correctly

Syzbot was able to trigger a data stream corruption:

WARNING: CPU: 0 PID: 9846 at net/mptcp/protocol.c:1024 __mptcp_clean_una+0xddb/0xff0 net/mptcp/protocol.c:1024 Modules linked in: CPU: 0 UID: 0 PID: 9846 Comm: syz-executor351 Not tainted 6.13.0-rc2-syzkaller-00059-g00a5acdbf398 #0 Hardware name: Google Compute Engine/Google Compute Engine, BIOS Google 11/25/2024 RIP: 0010:__mptcp_clean_una+0xddb/0xff0 net/mptcp/protocol.c:1024 Code: fa ff ff 48 8b 4c 24 18 80 e1 07 fe c1 38 c1 0f 8c 8e fa ff ff 48 8b 7c 24 18 e8 e0 db 54 f6 e9 7f fa ff ff e8 e6 80 ee f5 90 <0f> 0b 90 4c 8b 6c 24 40 4d 89 f4 e9 04 f5 ff ff 44 89 f1 80 e1 07 RSP: 0018:ffffc9000c0cf400 EFLAGS: 00010293 RAX: ffffffff8bb0dd5a RBX: ffff888033f5d230 RCX: ffff888059ce8000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffffc9000c0cf518 R08: ffffffff8bb0d1dd R09: 1ffff110170c8928 R10: dffffc0000000000 R11: ffffed10170c8929 R12: 0000000000000000 R13: ffff888033f5d220 R14: dffffc0000000000 R15: ffff8880592b8000 FS: 00007f6e866496c0(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f6e86f491a0 CR3: 00000000310e6000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __mptcp_clean_una_wakeup+0x7f/0x2d0 net/mptcp/protocol.c:1074 mptcp_release_cb+0x7cb/0xb30 net/mptcp/protocol.c:3493 release_sock+0x1aa/0x1f0 net/core/sock.c:3640 inet_wait_for_connect net/ipv4/af_inet.c:609 [inline] __inet_stream_connect+0x8bd/0xf30 net/ipv4/af_inet.c:703 mptcp_sendmsg_fastopen+0x2a2/0x530 net/mptcp/protocol.c:1755 mptcp_sendmsg+0x1884/0x1b10 net/mptcp/protocol.c:1830 sock_sendmsg_nosec net/socket.c:711 [inline] __sock_sendmsg+0x1a6/0x270 net/socket.c:726 ____sys_sendmsg+0x52a/0x7e0 net/socket.c:2583 ___sys_sendmsg net/socket.c:2637 [inline] __sys_sendmsg+0x269/0x350 net/socket.c:2669 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f6e86ebfe69 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 b1 1f 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f6e86649168 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f6e86f491b8 RCX: 00007f6e86ebfe69 RDX: 0000000030004001 RSI: 0000000020000080 RDI: 0000000000000003 RBP: 00007f6e86f491b0 R08: 00007f6e866496c0 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f6e86f491bc R13: 000000000000006e R14: 00007ffe445d9420 R15: 00007ffe445d9508

The root cause is the bad handling of disconnect() generated internally by the MPTCP protocol in case of connect FASTOPEN errors.

Address the issue increasing the socket disconnect counter even on such a case, to allow other threads waiting on the same socket lock to properly error out.

CVSS v3
5.5
EG Score
5.5(medium)
EG Risk
29(Track)
EG Risk 29/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity55% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
11%
KEV
Not listed

Published

February 27, 2025

Last Modified

July 14, 2026

Advisory Details (7)

Auto-updated Jul 17, 2026
Patch available.
generic

SSA-019113

https://cert-portal.siemens.com/productcert/html/ssa-019113.html
generic Patch Available

[SECURITY] [DLA 4102-1] linux-6.1 security update

https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html
generic

mptcp: handle fastopen disconnect correctly - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/84ac44d9fed3a56440971cbd7600a02b70b5b32a
generic

mptcp: handle fastopen disconnect correctly - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/73e268b4be27b36ae68ea10755cb003f43b38884
generic

mptcp: handle fastopen disconnect correctly - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/6ec806762318a4adde0ea63342d42d0feae95079
generic

mptcp: handle fastopen disconnect correctly - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/619af16b3b57a3a4ee50b9a30add9ff155541e71
generic

mptcp: handle fastopen disconnect correctly - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/0263fb2e7b7b88075a5d86e74c4384ee4400828d

Vendor Advisories for CVE-2025-21705(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(13)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulinux-virtual-hwe-24.04-edge (6.11.0-26.26) @ oracular2026-05-30ubuntu
ubuntulinux-tools-lowlatency-hwe-24.04-edge (6.11.0-1014.15~24.04.1) @ noble2026-05-30ubuntu
ubuntulinux-tools-aws (6.11.0-1014.15) @ oracular2026-05-30ubuntu
ubuntulinux-virtual-hwe-22.04-edge (6.8.0-64.67~22.04.1) @ jammy2026-05-30ubuntu
ubuntulinux-virtual-6.8 (6.8.0-64.67) @ noble2026-05-30ubuntu
ubuntulinux-tools-realtime-6.8.1 (6.8.1-1025.26) @ noble2026-05-30ubuntu
ubuntulinux-tools-oracle-lts-24.04 (6.8.0-1029.30) @ noble2026-05-30ubuntu
ubuntulinux-tools-lowlatency-hwe-20.04-edge (6.8.0-64.67.1) @ noble2026-05-30ubuntu
ubuntulinux-tools-raspi-6.8 (6.8.0-1031.35) @ noble2026-05-30ubuntu
ubuntulinux-tools-gcp-lts-24.04 (6.8.0-1033.35) @ noble2026-05-30ubuntu
ubuntulinux-tools-azure-nvidia-lts-24.04 (6.8.0-1022.23) @ noble2026-05-30ubuntu
ubuntulinux-tools-raspi-realtime-6.8 (6.8.0-2026.27) @ noble2026-05-30ubuntu
linuxKernel @ 6.1.129—osv

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

All Vendor Advisories

(12)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 7× in last 7d / 42× 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.

Showing the most recent 100 of 112 total refreshes for this CVE.

  1. 2026-08-07 16:26 UTCEPSS rescore
  2. 2026-08-06 13:46 UTCEPSS rescore
  3. 2026-08-05 19:16 UTCEPSS rescore
  4. 2026-08-04 15:09 UTCEPSS rescore
  5. 2026-08-04 10:37 UTCEPSS rescore
  6. 2026-08-03 10:35 UTCEPSS rescore
  7. 2026-08-02 02:25 UTCEPSS rescore
  8. 2026-08-01 04:15 UTCEPSS rescore
  9. 2026-07-30 16:27 UTCEPSS rescore
  10. 2026-07-30 01:29 UTCEPSS rescore
  11. 2026-07-28 15:35 UTCEPSS rescore
  12. 2026-07-27 14:12 UTCEPSS rescore
  13. 2026-07-26 14:53 UTCEPSS rescore
  14. 2026-07-25 14:17 UTCEPSS rescore
  15. 2026-07-24 14:17 UTCEPSS rescore
  16. 2026-07-24 13:41 UTCOSV refresh
  17. 2026-07-23 14:17 UTCEPSS rescore
  18. 2026-07-23 02:50 UTCEG score recompute
  19. 2026-07-22 14:07 UTCEPSS rescore
  20. 2026-07-22 14:07 UTCEPSS rescore
  21. 2026-07-21 15:24 UTCEPSS rescore
  22. 2026-07-20 17:07 UTCEPSS rescore
  23. 2026-07-19 14:30 UTCEPSS rescore
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  25. 2026-07-19 02:28 UTCEPSS rescore
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  1. 2026-07-19 02:28 UTCEPSS rescore
  2. 2026-07-18 10:03 UTCEPSS rescore
  3. 2026-07-16 17:02 UTCEPSS rescore
  4. 2026-07-15 16:57 UTCEPSS rescore
  5. 2026-07-15 16:57 UTCEPSS rescore
  6. 2026-07-15 01:59 UTCEPSS rescore
  7. 2026-07-14 13:19 UTCNVD updateCVSS v3 → 5.5 · severity → MEDIUM
  8. 2026-07-14 13:11 UTCMITRE cvelistV5
  9. 2026-07-13 22:29 UTCEPSS rescore
  10. 2026-07-13 22:29 UTCEPSS rescore
  11. 2026-07-13 06:12 UTCEPSS rescore
  12. 2026-07-13 06:12 UTCEPSS rescore
  13. 2026-07-12 05:46 UTCEPSS rescore
  14. 2026-07-12 05:46 UTCEPSS rescore
  15. 2026-07-11 08:27 UTCEPSS rescore
  16. 2026-07-11 08:26 UTCEPSS rescore
  17. 2026-07-09 19:09 UTCEPSS rescore
  18. 2026-07-08 15:14 UTCEPSS rescore
  19. 2026-07-07 13:45 UTCEPSS rescore
  20. 2026-07-07 09:21 UTCOSV refresh
  21. 2026-07-06 16:26 UTCEPSS rescore
  22. 2026-07-06 02:22 UTCEPSS rescore
  23. 2026-07-06 02:22 UTCEPSS rescore
  24. 2026-07-05 02:30 UTCEPSS rescore
  25. 2026-07-04 06:30 UTCEPSS rescore
  26. 2026-07-01 15:06 UTCEPSS rescore
  27. 2026-06-30 23:21 UTCEPSS rescore
  28. 2026-06-30 23:21 UTCEPSS rescore
  29. 2026-06-29 14:06 UTCEPSS rescore
  30. 2026-06-28 14:07 UTCEPSS rescore
  31. 2026-06-28 14:07 UTCEPSS rescore
  32. 2026-06-28 04:55 UTCEPSS rescore
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  34. 2026-06-27 03:08 UTCEPSS rescore
  35. 2026-06-27 03:08 UTCEPSS rescore
  36. 2026-06-25 13:49 UTCEPSS rescore
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  38. 2026-06-24 14:04 UTCEPSS rescore
  39. 2026-06-24 14:04 UTCEPSS rescore
  40. 2026-06-23 21:32 UTCEPSS rescore
  41. 2026-06-23 21:32 UTCEPSS rescore
  42. 2026-06-22 14:25 UTCEPSS rescore
  43. 2026-06-22 14:25 UTCEPSS rescore
  44. 2026-06-21 14:56 UTCEPSS rescore
  45. 2026-06-21 14:56 UTCEPSS rescore
  46. 2026-06-21 01:59 UTCEPSS rescore
  47. 2026-06-21 01:59 UTCEPSS rescore
  48. 2026-06-19 19:25 UTCEPSS rescore
  49. 2026-06-19 19:25 UTCEPSS rescore
  50. 2026-06-18 20:13 UTCOSV refresh
  51. 2026-06-18 17:52 UTCEPSS rescore
  52. 2026-06-18 17:52 UTCEPSS rescore
  53. 2026-06-17 17:52 UTCEPSS rescore
  54. 2026-06-16 17:52 UTCEPSS rescore
  55. 2026-06-16 17:52 UTCEPSS rescore
  56. 2026-06-15 17:48 UTCEPSS rescore
  57. 2026-06-14 23:17 UTCEPSS rescore
  58. 2026-06-13 22:59 UTCEPSS rescore
  59. 2026-06-12 23:11 UTCEPSS rescore
  60. 2026-06-11 13:59 UTCEPSS rescore
  61. 2026-06-10 22:18 UTCEPSS rescore
  62. 2026-06-10 13:22 UTCEPSS rescore
  63. 2026-06-08 14:16 UTCEPSS rescore
  64. 2026-06-08 14:16 UTCEPSS rescore
  65. 2026-06-07 15:24 UTCEPSS rescore
  66. 2026-06-07 15:24 UTCEPSS rescore
  67. 2026-06-06 13:47 UTCEPSS rescore
  68. 2026-06-06 13:47 UTCEPSS rescore
  69. 2026-06-05 22:46 UTCEPSS rescore
  70. 2026-06-05 22:46 UTCEPSS rescore
  71. 2026-06-05 06:10 UTCEPSS rescore
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  73. 2026-06-04 13:11 UTCEPSS rescore
  74. 2026-06-04 13:11 UTCEPSS rescore
  75. 2026-06-02 20:12 UTCEPSS rescore

Related CVEs(same product + same vendor)

Frequently asked(5)

What is CVE-2025-21705?
CVE-2025-21705 is a medium vulnerability published on February 27, 2025. In the Linux kernel, the following vulnerability has been resolved: mptcp: handle fastopen disconnect correctly Syzbot was able to trigger a data stream corruption: WARNING: CPU: 0 PID: 9846 at net/mptcp/protocol.c:1024 mptcpcleanuna+0xddb/0xff0 net/mptcp/protocol.c:1024 Modules linked in: CPU: 0…
When was CVE-2025-21705 disclosed?
CVE-2025-21705 was first published in the National Vulnerability Database on February 27, 2025, with the most recent update on July 14, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2025-21705 actively exploited?
CVE-2025-21705 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 89.3% of all scored CVEs.
What is the CVSS score of CVE-2025-21705?
CVE-2025-21705 has a CVSS v3 base score of 5.5 (NVD).
How do I remediate CVE-2025-21705?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2025-21705, 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.

Dependency Blast Radius

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