CVE-2026-64191

HIGHPre-NVD 7.87.8—
EchelonGraph scoreMEDIUM confidence

Score 7.8 from GitHub Security Advisory (severity: HIGH) published 2026-07-20. a secondary CVSS source baseline 7.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — Patch released this week
7.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.8Exploit: None knownExposed: 0

A fix is available — apply it.

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

i2c: stub: Reject I2C block transfers with invalid length

The I2C_SMBUS_I2C_BLOCK_DATA case in stub_xfer() uses data->block[0] as the transfer length. The existing check only clamps it to avoid overrunning the chip->words[256] register array, but does not validate it against I2C_SMBUS_BLOCK_MAX (32), which is the limit of the union i2c_smbus_data.block buffer (34 bytes total). The driver is a development/test tool (CONFIG_I2C_STUB=m, not built by default) that must be loaded with a chip_addr= parameter.

A local user with access to /dev/i2c-* can issue an I2C_SMBUS ioctl with I2C_SMBUS_I2C_BLOCK_DATA and data->block[0] > 32, causing stub_xfer() to read or write past the end of the union i2c_smbus_data.block buffer:

BUG: KASAN: stack-out-of-bounds in stub_xfer (drivers/i2c/i2c-stub.c:223) Read of size 1 at addr ffff88800abcfd92 by task exploit/81 Call Trace: stub_xfer (drivers/i2c/i2c-stub.c:223) __i2c_smbus_xfer (drivers/i2c/i2c-core-smbus.c:593) i2c_smbus_xfer (drivers/i2c/i2c-core-smbus.c:536) i2cdev_ioctl_smbus (drivers/i2c/i2c-dev.c:391) i2cdev_ioctl (drivers/i2c/i2c-dev.c:478) __x64_sys_ioctl (fs/ioctl.c:583) do_syscall_64 (arch/x86/entry/syscall_64.c:94) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)

The bug exists because i2c-stub implements .smbus_xfer directly, bypassing the I2C_SMBUS_BLOCK_MAX validation in i2c_smbus_xfer_emulated(). The I2C_SMBUS_BLOCK_DATA case in the same function correctly validates against I2C_SMBUS_BLOCK_MAX, but the I2C_SMBUS_I2C_BLOCK_DATA case does not.

Fix by rejecting transfers with data->block[0] == 0 or data->block[0] > I2C_SMBUS_BLOCK_MAX with -EINVAL, consistent with both the I2C_SMBUS_BLOCK_DATA case in the same function and the I2C_SMBUS_I2C_BLOCK_DATA validation in i2c_smbus_xfer_emulated().

CVSS v3
7.8
EG Score
7.8(medium)
EG Risk
40(Track)
EG Risk 40/100SSVC: 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
Severity78% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
3%
KEV
Not listed

Published

July 20, 2026

Last Modified

August 11, 2026

Advisory Details (8)

Auto-updated Jul 27, 2026
No patch confirmed yet.
generic

i2c: stub: Reject I2C block transfers with invalid length - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/7e9072dbd5f2f17934751873450d2c22080ead80
generic

i2c: stub: Reject I2C block transfers with invalid length - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/6036b5067a8199ba7a2dc7b377d4b9dd276d5f9e
generic

i2c: stub: Reject I2C block transfers with invalid length - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/5f4d2bd028ebb6e4c09a9d64842546022321d4a7
generic

i2c: stub: Reject I2C block transfers with invalid length - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/4bd8635f28c135a08aac6badcd7d9b5cdb34335f
generic

i2c: stub: Reject I2C block transfers with invalid length - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/3fd225f3e4cd67ec8ddab1afed9da03c7c43537c
generic

i2c: stub: Reject I2C block transfers with invalid length - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/21e87f336ac6303fed54a69b1d0d79a23b25c8d0
generic

i2c: stub: Reject I2C block transfers with invalid length - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/1c4ffe6b4f04365485ed58d64c9bb86b46fc9037
generic

i2c: stub: Reject I2C block transfers with invalid length - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/0526931b16e5a118d367b7bfce7d797e63f7ac69

Vendor Advisories for CVE-2026-64191(9)

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

Patch Availability(10)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulinux-virtual-hwe-26.04-edge (7.0.0-31.31) @ resolute2026-09-11ubuntu
ubuntulinux-tools-oem-7.0 (7.0.0-1013.13) @ resolute2026-09-11ubuntu
ubuntulinux-tools-gcp-edge (7.0.0-1011.11~24.04.1) @ noble2026-09-11ubuntu
redhatkernel-0:4.18.0-305.206.1.el8_42026-09-09redhat
redhatkernel-0:4.18.0-372.213.1.el8_62026-09-09redhat
redhatkernel-0:4.18.0-477.166.1.el8_82026-09-09redhat
redhatkernel-0:5.14.0-570.140.1.el9_62026-09-09redhat
redhatkernel-0:4.18.0-553.158.1.el8_102026-08-26redhat
redhatkernel-0:5.14.0-687.42.1.el9_82026-08-26redhat
redhatkernel-rt-0:4.18.0-553.158.1.rt7.499.el8_102026-08-26redhat

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

(5 across 4 ecosystems)
Debian:11(2)
PackageVulnerable rangeFixed inDependents
linux5.10.103-1 ... 5.10.92-2 (55 versions)5.10.262-1—
linux-6.16.1.106-3~deb11u1 ... 6.1.176-1~deb11u1 (21 versions)6.1.177-1~deb11u1—
Debian:12(1)
PackageVulnerable rangeFixed inDependents
linux6.1.106-1 ... 6.1.99-1 (54 versions)6.1.177-1—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
linux6.12.38-1 ... 6.12.95-1~bpo12+1 (29 versions)6.12.95-1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
linux6.12.100-1 ... 7.0.9-1~bpo13+1 (146 versions)7.0.14-1—

Weakness Classification(1)

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

Additional Vendor Advisories

(3)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 23× in last 7d / 121× 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 430 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-64191?
CVE-2026-64191 is a high vulnerability published on July 20, 2026. In the Linux kernel, the following vulnerability has been resolved: i2c: stub: Reject I2C block transfers with invalid length The I2CSMBUSI2CBLOCKDATA case in stub_xfer() uses data->block[0] as the transfer length. The existing check only clamps it to avoid overrunning the chip->words[256] register…
When was CVE-2026-64191 disclosed?
CVE-2026-64191 was first published in the National Vulnerability Database on July 20, 2026, with the most recent update on August 11, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-64191 actively exploited?
CVE-2026-64191 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 97.3% of all scored CVEs.
What is the CVSS score of CVE-2026-64191?
CVE-2026-64191 has a CVSS v3 base score of 7.8 (NVD).
How do I remediate CVE-2026-64191?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-64191, 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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