CVE-2026-63944

HIGHPre-NVD 8.88.8
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

Score 8.8 from GitHub Security Advisory (severity: HIGH) published 2026-07-19. A secondary CVSS source baseline 8.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, a secondary CVSS source
Trending — 4 sources updated this week
8.8EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 8.8Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

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

Bluetooth: hci_sync: fix UAF in hci_le_create_cis_sync

hci_le_create_cis_sync() dereferences conn->conn_timeout after releasing both rcu_read_lock() and hci_dev_lock(hdev). The conn pointer was obtained from an RCU-protected iteration over hdev->conn_hash.list and is not valid once these locks are dropped. A concurrent disconnect can free the hci_conn between the unlock and the dereference, causing a use-after-free read.

The cancellation mechanism in hci_conn_del() cannot prevent this because hci_le_create_cis_pending() queues hci_create_cis_sync with data=NULL:

hci_cmd_sync_queue(hdev, hci_create_cis_sync, NULL, NULL);

While hci_conn_del() dequeues with data=conn:

hci_cmd_sync_dequeue(hdev, NULL, conn, NULL);

Since NULL != conn, the lookup in _hci_cmd_sync_lookup_entry() never matches, and the pending work item is not cancelled.

Fix this by saving conn->conn_timeout into a local variable while the locks are still held, so the stale conn pointer is never dereferenced after unlock.

This is the same class of bug as the one fixed by commit 035c25007c9e ("Bluetooth: hci_sync: Fix UAF on le_read_features_complete") which addressed the identical pattern in a different function.

This vulnerability was identified using 0sec.ai, an open-source automated security auditing platform (https://github.com/0sec-labs).

CVSS v3
8.8
EG Score
8.8HIGHmedium confidence
EG Risk
40
EG Risk 40/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity88% × 45%
Impact severity (EG Severity): CVSS 8.8 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.3% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.3%
EPSS %ILE
25th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (8.8): severity, escalated by confirmed exploitation. This CVE's 8.8 is its impact severity (EG Severity), not escalated.

EG Severity
8.8 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.3% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-19). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

July 19, 2026

Last Modified

October 19, 2026

Advisory Details (5)

Auto-updated Jul 20, 2026
Patch available.
Web page

Bluetooth: hci_sync: fix UAF in hci_le_create_cis_sync - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/d9019210c8c30d40eb20094274cc647e352f48f7
Web page

Bluetooth: hci_sync: fix UAF in hci_le_create_cis_sync - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/bfea6091e0fffb270c20e74384b660910277eb6c
Web page

Bluetooth: hci_sync: fix UAF in hci_le_create_cis_sync - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/a921957d39290143629eb38c4f74b9bef8035d0a
Web page

Bluetooth: hci_sync: fix UAF in hci_le_create_cis_sync - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/a55618c0f4cead9e59c63f5ee030d393fd70d861
Web page

Bluetooth: hci_sync: fix UAF in hci_le_create_cis_sync - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/380e67b1794a9a281a0cb592b4e62077fbd0c8ca

Patch Availability(17)

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

(2 across 2 ecosystems)
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
linux6.12.38-1 ... 6.12.94-1~bpo12+1 (27 versions)
  • every version up to 6.12.94-1: fixed in 6.12.94-1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
linux6.12.100-1 ... 7.0.9-1~bpo13+1 (142 versions)
  • every version up to 7.0.12-1: fixed in 7.0.12-1
—

Weakness Classification(1)

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

Additional Vendor Advisories

(15)

Data Freshness Timeline

(refreshed 20× in last 7d / 55× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 100 of 334 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 234 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-19 21:39 UTCEG score recompute
  2. 2026-10-19 21:39 UTCVendor advisory
  3. 2026-10-19 21:38 UTCGHSA enrichmentGHSA-q8jf-94w2-5pjv · GitHub severity HIGH · GitHub CVSS 8.8
  4. 2026-10-19 20:37 UTCEG score recompute
  5. 2026-10-19 20:37 UTCVendor advisory
  6. 2026-10-19 20:36 UTCGHSA enrichmentGHSA-q8jf-94w2-5pjv · GitHub severity HIGH · GitHub CVSS 8.8
  7. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  8. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  9. 2026-10-18 03:23 UTCEG score recompute
  10. 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  11. 2026-10-16 17:19 UTCEG score recompute
  12. 2026-10-16 17:19 UTCVendor advisory
  13. 2026-10-16 17:18 UTCGHSA enrichmentGHSA-q8jf-94w2-5pjv · GitHub severity HIGH · GitHub CVSS 8.8
  14. 2026-10-16 16:43 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  15. 2026-10-16 15:54 UTCEG score recompute
  16. 2026-10-16 15:54 UTCVendor advisory
  17. 2026-10-16 15:54 UTCGHSA enrichmentGHSA-q8jf-94w2-5pjv · GitHub severity HIGH · GitHub CVSS 8.8
  18. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  19. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  20. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  21. 2026-10-13 11:49 UTCEG score recompute
  22. 2026-10-13 11:49 UTCVendor advisory
  23. 2026-10-13 11:49 UTCGHSA enrichmentGHSA-q8jf-94w2-5pjv · GitHub severity HIGH · GitHub CVSS 8.8
  24. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  25. 2026-10-12 15:48 UTCEG score recompute
Show 75 more
  1. 2026-10-11 19:33 UTCEG score recompute
  2. 2026-10-11 16:48 UTCEG score recompute
  3. 2026-10-11 14:09 UTCEG score recompute
  4. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  5. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  6. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  7. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  8. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  9. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  10. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  11. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  12. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  13. 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  14. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  15. 2026-10-01 08:50 UTCEG score recompute
  16. 2026-10-01 08:50 UTCVendor advisory
  17. 2026-10-01 08:50 UTCGHSA enrichmentGHSA-q8jf-94w2-5pjv · GitHub severity HIGH · GitHub CVSS 8.8
  18. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  19. 2026-09-28 07:27 UTCEG score recompute
  20. 2026-09-28 07:27 UTCVendor advisory
  21. 2026-09-28 07:27 UTCGHSA enrichmentGHSA-q8jf-94w2-5pjv · GitHub severity HIGH · GitHub CVSS 8.8
  22. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  23. 2026-09-24 04:13 UTCEG score recompute
  24. 2026-09-24 04:13 UTCVendor advisory
  25. 2026-09-24 04:13 UTCGHSA enrichmentGHSA-q8jf-94w2-5pjv · GitHub severity HIGH · GitHub CVSS 8.8
  26. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  27. 2026-09-23 02:09 UTCEG score recompute
  28. 2026-09-23 02:09 UTCVendor advisory
  29. 2026-09-23 02:09 UTCGHSA enrichmentGHSA-q8jf-94w2-5pjv · GitHub severity HIGH · GitHub CVSS 8.8
  30. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  31. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  32. 2026-09-18 04:22 UTCEG score recompute
  33. 2026-09-18 04:22 UTCVendor advisory
  34. 2026-09-18 04:22 UTCGHSA enrichmentGHSA-q8jf-94w2-5pjv · GitHub severity HIGH · GitHub CVSS 8.8
  35. 2026-09-17 05:36 UTCEG score recompute
  36. 2026-09-17 05:36 UTCVendor advisory
  37. 2026-09-17 05:36 UTCGHSA enrichmentGHSA-q8jf-94w2-5pjv · GitHub severity HIGH · GitHub CVSS 8.8
  38. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  39. 2026-09-16 13:06 UTCEG score recompute
  40. 2026-09-16 13:06 UTCVendor advisory
  41. 2026-09-16 13:06 UTCGHSA enrichmentGHSA-q8jf-94w2-5pjv · GitHub severity HIGH · GitHub CVSS 8.8
  42. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  43. 2026-09-14 05:23 UTCVendor advisory
  44. 2026-09-14 05:23 UTCGHSA enrichmentGHSA-q8jf-94w2-5pjv · GitHub severity HIGH · GitHub CVSS 8.8
  45. 2026-09-13 18:30 UTCEG score recompute
  46. 2026-09-13 18:30 UTCVendor advisory
  47. 2026-09-13 18:30 UTCGHSA enrichmentGHSA-q8jf-94w2-5pjv · GitHub severity HIGH · GitHub CVSS 8.8
  48. 2026-09-13 07:03 UTCVendor advisory
  49. 2026-09-13 07:03 UTCGHSA enrichmentGHSA-q8jf-94w2-5pjv · GitHub severity HIGH · GitHub CVSS 8.8
  50. 2026-09-12 19:57 UTCEG score recompute
  51. 2026-09-12 19:57 UTCVendor advisory
  52. 2026-09-12 19:57 UTCGHSA enrichmentGHSA-q8jf-94w2-5pjv · GitHub severity HIGH · GitHub CVSS 8.8
  53. 2026-09-12 07:18 UTCVendor advisory
  54. 2026-09-12 07:18 UTCGHSA enrichmentGHSA-q8jf-94w2-5pjv · GitHub severity HIGH · GitHub CVSS 8.8
  55. 2026-09-11 19:39 UTCEG score recompute
  56. 2026-09-11 19:39 UTCVendor advisory
  57. 2026-09-11 19:39 UTCGHSA enrichmentGHSA-q8jf-94w2-5pjv · GitHub severity HIGH · GitHub CVSS 8.8
  58. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  59. 2026-09-11 09:37 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  60. 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  61. 2026-09-07 23:28 UTCEG score recompute
  62. 2026-09-07 23:28 UTCVendor advisory
  63. 2026-09-07 23:28 UTCGHSA enrichmentGHSA-q8jf-94w2-5pjv · GitHub severity HIGH · GitHub CVSS 8.8
  64. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  65. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  66. 2026-09-06 12:59 UTCVendor advisory
  67. 2026-09-06 12:59 UTCGHSA enrichmentGHSA-q8jf-94w2-5pjv · GitHub severity HIGH · GitHub CVSS 8.8
  68. 2026-09-05 20:08 UTCEG score recompute
  69. 2026-09-05 20:08 UTCVendor advisory
  70. 2026-09-05 20:08 UTCGHSA enrichmentGHSA-q8jf-94w2-5pjv · GitHub severity HIGH · GitHub CVSS 8.8
  71. 2026-09-05 15:31 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  72. 2026-09-04 05:07 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  73. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  74. 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  75. 2026-09-01 04:40 UTCEPSS rescoreEPSS 0.3% · 24th percentile

Frequently asked(5)

What is CVE-2026-63944?
CVE-2026-63944 is a high-severity vulnerability; its CVE record was published on July 19, 2026. In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hcisync: fix UAF in hcilecreatecis_sync hcilecreatecissync() dereferences conn->conn_timeout after releasing both rcureadlock() and hcidevlock(hdev). The conn pointer was obtained from an RCU-protected iteration over…
When was the CVE record for CVE-2026-63944 published?
The CVE record for CVE-2026-63944 was published on July 19, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of October 19, 2026; the record at its source may have been updated since.
Is CVE-2026-63944 actively exploited?
CVE-2026-63944 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (25th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-63944?
CVE-2026-63944 has a CVSS base score of 8.8 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-63944?
A fix for CVE-2026-63944 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-63944 are linked in the Vendor Advisories panel on this page.

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