CVE-2025-21673

MEDIUMNVD 5.55.5—
EchelonGraph scoreMEDIUM confidence

Score 5.5 from GitHub Security Advisory published 2025-01-31. 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:

smb: client: fix double free of TCP_Server_Info::hostname

When shutting down the server in cifs_put_tcp_session(), cifsd thread might be reconnecting to multiple DFS targets before it realizes it should exit the loop, so @server->hostname can't be freed as long as cifsd thread isn't done. Otherwise the following can happen:

RIP: 0010:__slab_free+0x223/0x3c0 Code: 5e 41 5f c3 cc cc cc cc 4c 89 de 4c 89 cf 44 89 44 24 08 4c 89 1c 24 e8 fb cf 8e 00 44 8b 44 24 08 4c 8b 1c 24 e9 5f fe ff ff <0f> 0b 41 f7 45 08 00 0d 21 00 0f 85 2d ff ff ff e9 1f ff ff ff 80 RSP: 0018:ffffb26180dbfd08 EFLAGS: 00010246 RAX: ffff8ea34728e510 RBX: ffff8ea34728e500 RCX: 0000000000800068 RDX: 0000000000800068 RSI: 0000000000000000 RDI: ffff8ea340042400 RBP: ffffe112041ca380 R08: 0000000000000001 R09: 0000000000000000 R10: 6170732e31303000 R11: 70726f632e786563 R12: ffff8ea34728e500 R13: ffff8ea340042400 R14: ffff8ea34728e500 R15: 0000000000800068 FS: 0000000000000000(0000) GS:ffff8ea66fd80000(0000) 000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffc25376080 CR3: 000000012a2ba001 CR4: PKRU: 55555554 Call Trace: ? show_trace_log_lvl+0x1c4/0x2df ? show_trace_log_lvl+0x1c4/0x2df ? __reconnect_target_unlocked+0x3e/0x160 [cifs] ? __die_body.cold+0x8/0xd ? die+0x2b/0x50 ? do_trap+0xce/0x120 ? __slab_free+0x223/0x3c0 ? do_error_trap+0x65/0x80 ? __slab_free+0x223/0x3c0 ? exc_invalid_op+0x4e/0x70 ? __slab_free+0x223/0x3c0 ? asm_exc_invalid_op+0x16/0x20 ? __slab_free+0x223/0x3c0 ? extract_hostname+0x5c/0xa0 [cifs] ? extract_hostname+0x5c/0xa0 [cifs] ? __kmalloc+0x4b/0x140 __reconnect_target_unlocked+0x3e/0x160 [cifs] reconnect_dfs_server+0x145/0x430 [cifs] cifs_handle_standard+0x1ad/0x1d0 [cifs] cifs_demultiplex_thread+0x592/0x730 [cifs] ? __pfx_cifs_demultiplex_thread+0x10/0x10 [cifs] kthread+0xdd/0x100 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x29/0x50

CVSS v3
5.5
EG Score
5.5(medium)
EG Risk
25(Track)
EG Risk 25/100SSVC: 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%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
35%
KEV
Not listed

Published

January 31, 2025

Last Modified

August 5, 2026

Advisory Details (3)

Auto-updated Aug 2, 2026
No patch confirmed yet.
generic

smb: client: fix double free of TCP_Server_Info::hostname - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/fa2f9906a7b333ba757a7dbae0713d8a5396186e
generic

smb: client: fix double free of TCP_Server_Info::hostname - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/a2be5f2ba34d0c6d5ef2624b24e3d852561fcd6a
generic

smb: client: fix double free of TCP_Server_Info::hostname - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/1ea68070338518a1d31ce71e6abfe1b30001b27a

Patch Availability(11)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulinux-virtual (6.8.0-62.65) @ noble2026-05-30ubuntu
ubuntulinux-virtual-hwe-24.04-edge (6.11.0-24.24+1) @ oracular2026-05-30ubuntu
ubuntulinux-tools-azure (6.11.0-1013.13) @ oracular2026-05-30ubuntu
ubuntulinux-tools-realtime (6.8.1-1023.24) @ noble2026-05-30ubuntu
ubuntulinux-tools-azure-lts-24.04 (6.8.0-1030.35) @ noble2026-05-30ubuntu
ubuntulinux-tools-azure-nvidia (6.8.0-1018.19) @ noble2026-05-30ubuntu
ubuntulinux-tools-raspi (6.8.0-1029.33) @ noble2026-05-30ubuntu
ubuntulinux-tools-raspi-realtime (6.8.0-2024.25) @ noble2026-05-30ubuntu
ubuntulinux-tools-gcp-lts-24.04 (6.8.0-1031.33) @ noble2026-05-30ubuntu
ubuntulinux-virtual-hwe-22.04-edge (6.8.0-64.67~22.04.1) @ jammy2026-05-30ubuntu
linuxKernel @ 6.6.74—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.

Affected Packages

(3 across 3 ecosystems)
Debian:12(1)
PackageVulnerable rangeFixed inDependents
linux6.1.106-1 ... 7.2~rc7-1~exp1 (350 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
linux—6.12.11-1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
linux—6.12.11-1—

Weakness Classification(1)

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

All Vendor Advisories

(11)

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 5× in last 7d / 26× 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 152 total refreshes for this CVE.

  1. 2026-09-18 19:27 UTCEPSS rescore
  2. 2026-09-16 14:06 UTCEPSS rescore
  3. 2026-09-16 05:13 UTCEPSS rescore
  4. 2026-09-15 03:09 UTCEPSS rescore
  5. 2026-09-13 16:46 UTCEPSS rescore
  6. 2026-09-12 15:00 UTCEPSS rescore
  7. 2026-09-11 14:51 UTCEPSS rescore
  8. 2026-09-11 09:35 UTCEPSS rescore
  9. 2026-09-10 09:33 UTCEPSS rescore
  10. 2026-09-08 21:59 UTCEPSS rescore
  11. 2026-09-07 16:00 UTCEPSS rescore
  12. 2026-09-07 13:18 UTCOSV refresh
  13. 2026-09-06 13:46 UTCEPSS rescore
  14. 2026-09-06 13:46 UTCEPSS rescore
  15. 2026-09-05 15:28 UTCEPSS rescore
  16. 2026-09-04 05:05 UTCEPSS rescore
  17. 2026-09-02 14:11 UTCEPSS rescore
  18. 2026-09-01 13:52 UTCEPSS rescore
  19. 2026-09-01 04:38 UTCEPSS rescore
  20. 2026-08-30 19:16 UTCEPSS rescore
  21. 2026-08-30 01:21 UTCEPSS rescore
  22. 2026-08-28 21:40 UTCEPSS rescore
  23. 2026-08-27 14:24 UTCEPSS rescore
  24. 2026-08-25 13:47 UTCEPSS rescore
  25. 2026-08-23 00:18 UTCEPSS rescore
Show 75 more
  1. 2026-08-21 23:48 UTCEPSS rescore
  2. 2026-08-20 22:54 UTCEPSS rescore
  3. 2026-08-20 22:31 UTCOSV refresh
  4. 2026-08-19 17:03 UTCEPSS rescore
  5. 2026-08-18 13:47 UTCEPSS rescore
  6. 2026-08-17 13:46 UTCEPSS rescore
  7. 2026-08-16 14:55 UTCEPSS rescore
  8. 2026-08-16 02:13 UTCEPSS rescore
  9. 2026-08-16 02:13 UTCEPSS rescore
  10. 2026-08-15 01:29 UTCEPSS rescore
  11. 2026-08-13 21:59 UTCEPSS rescore
  12. 2026-08-12 13:50 UTCEPSS rescore
  13. 2026-08-10 23:59 UTCEPSS rescore
  14. 2026-08-09 13:45 UTCEPSS rescore
  15. 2026-08-07 16:26 UTCEPSS rescore
  16. 2026-08-06 13:46 UTCEPSS rescore
  17. 2026-08-05 19:16 UTCEPSS rescore
  18. 2026-08-05 14:06 UTCEG score recompute
  19. 2026-08-05 14:06 UTCVendor advisory
  20. 2026-08-05 14:05 UTCGHSA enrichment
  21. 2026-08-04 15:09 UTCEPSS rescore
  22. 2026-08-04 10:37 UTCEPSS rescore
  23. 2026-08-03 10:35 UTCEPSS rescore
  24. 2026-08-01 04:15 UTCEPSS rescore
  25. 2026-07-30 16:27 UTCEPSS rescore
  26. 2026-07-30 07:24 UTCEG score recompute
  27. 2026-07-30 07:24 UTCVendor advisory
  28. 2026-07-30 07:24 UTCGHSA enrichment
  29. 2026-07-30 01:29 UTCEPSS rescore
  30. 2026-07-28 15:35 UTCEPSS rescore
  31. 2026-07-27 14:12 UTCEPSS rescore
  32. 2026-07-26 14:53 UTCEPSS rescore
  33. 2026-07-25 14:17 UTCEPSS rescore
  34. 2026-07-24 16:41 UTCOSV refresh
  35. 2026-07-24 14:17 UTCEPSS rescore
  36. 2026-07-23 14:17 UTCEPSS rescore
  37. 2026-07-23 02:50 UTCEG score recompute
  38. 2026-07-22 14:07 UTCEPSS rescore
  39. 2026-07-22 14:07 UTCEPSS rescore
  40. 2026-07-21 15:24 UTCEPSS rescore
  41. 2026-07-20 17:07 UTCEPSS rescore
  42. 2026-07-19 14:30 UTCEPSS rescore
  43. 2026-07-19 14:30 UTCEPSS rescore
  44. 2026-07-19 02:28 UTCEPSS rescore
  45. 2026-07-19 02:28 UTCEPSS rescore
  46. 2026-07-18 10:03 UTCEPSS rescore
  47. 2026-07-16 17:02 UTCEPSS rescore
  48. 2026-07-15 01:59 UTCEPSS rescore
  49. 2026-07-13 22:29 UTCEPSS rescore
  50. 2026-07-13 22:29 UTCEPSS rescore
  51. 2026-07-13 06:12 UTCEPSS rescore
  52. 2026-07-13 06:12 UTCEPSS rescore
  53. 2026-07-12 05:46 UTCEPSS rescore
  54. 2026-07-12 05:46 UTCEPSS rescore
  55. 2026-07-11 08:27 UTCEPSS rescore
  56. 2026-07-11 08:26 UTCEPSS rescore
  57. 2026-07-09 19:09 UTCEPSS rescore
  58. 2026-07-08 15:14 UTCEPSS rescore
  59. 2026-07-07 13:45 UTCEPSS rescore
  60. 2026-07-07 11:51 UTCOSV refresh
  61. 2026-07-06 16:26 UTCEPSS rescore
  62. 2026-07-06 02:22 UTCEPSS rescore
  63. 2026-07-06 02:22 UTCEPSS rescore
  64. 2026-07-05 02:30 UTCEPSS rescore
  65. 2026-07-04 06:30 UTCEPSS rescore
  66. 2026-07-01 15:06 UTCEPSS rescore
  67. 2026-06-30 23:21 UTCEPSS rescore
  68. 2026-06-30 23:21 UTCEPSS rescore
  69. 2026-06-29 14:06 UTCEPSS rescore
  70. 2026-06-28 14:07 UTCEPSS rescore
  71. 2026-06-28 14:07 UTCEPSS rescore
  72. 2026-06-28 04:55 UTCEPSS rescore
  73. 2026-06-28 04:55 UTCEPSS rescore
  74. 2026-06-27 03:08 UTCEPSS rescore
  75. 2026-06-27 03:08 UTCEPSS rescore

Frequently asked(5)

What is CVE-2025-21673?
CVE-2025-21673 is a medium vulnerability published on January 31, 2025. In the Linux kernel, the following vulnerability has been resolved: smb: client: fix double free of TCPServerInfo::hostname When shutting down the server in cifsputtcp_session(), cifsd thread might be reconnecting to multiple DFS targets before it realizes it should exit the loop, so…
When was CVE-2025-21673 disclosed?
CVE-2025-21673 was first published in the National Vulnerability Database on January 31, 2025, with the most recent update on August 5, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2025-21673 actively exploited?
CVE-2025-21673 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 64.9% of all scored CVEs.
What is the CVSS score of CVE-2025-21673?
CVE-2025-21673 has a CVSS v3 base score of 5.5 (NVD).
How do I remediate CVE-2025-21673?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2025-21673, 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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