CVE-2026-45866

HIGHNVD 7.87.8—
EchelonGraph scoreMEDIUM confidence

Score 7.8 from GitHub Security Advisory (severity: HIGH) published 2026-05-27. NVD baseline CVSS 7.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
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:

serial: caif: fix use-after-free in caif_serial ldisc_close()

There is a use-after-free bug in caif_serial where handle_tx() may access ser->tty after the tty has been freed.

The race condition occurs between ldisc_close() and packet transmission:

CPU 0 (close) CPU 1 (xmit) ------------- ------------ ldisc_close() tty_kref_put(ser->tty) [tty may be freed here] <-- race window --> caif_xmit() handle_tx() tty = ser->tty // dangling ptr tty->ops->write() // UAF! schedule_work() ser_release() unregister_netdevice()

The root cause is that tty_kref_put() is called in ldisc_close() while the network device is still active and can receive packets.

Since ser and tty have a 1:1 binding relationship with consistent lifecycles (ser is allocated in ldisc_open and freed in ser_release via unregister_netdevice, and each ser binds exactly one tty), we can safely defer the tty reference release to ser_release() where the network device is unregistered.

Fix this by moving tty_kref_put() from ldisc_close() to ser_release(), after unregister_netdevice(). This ensures the tty reference is held as long as the network device exists, preventing the UAF.

Note: We save ser->tty before unregister_netdevice() because ser is embedded in netdev's private data and will be freed along with netdev (needs_free_netdev = true).

How to reproduce: Add mdelay(500) at the beginning of ldisc_close() to widen the race window, then run the reproducer program [1].

Note: There is a separate deadloop issue in handle_tx() when using PORT_UNKNOWN serial ports (e.g., /dev/ttyS3 in QEMU without proper serial backend). This deadloop exists even without this patch, and is likely caused by inconsistency between uart_write_room() and uart_write() in serial core. It has been addressed in a separate patch [2].

KASAN report:

================================================================== BUG: KASAN: slab-use-after-free in handle_tx+0x5d1/0x620 Read of size 1 at addr ffff8881131e1490 by task caif_uaf_trigge/9929

Call Trace: dump_stack_lvl+0x10e/0x1f0 print_report+0xd0/0x630 kasan_report+0xe4/0x120 handle_tx+0x5d1/0x620 dev_hard_start_xmit+0x9d/0x6c0 __dev_queue_xmit+0x6e2/0x4410 packet_xmit+0x243/0x360 packet_sendmsg+0x26cf/0x5500 __sys_sendto+0x4a3/0x520 __x64_sys_sendto+0xe0/0x1c0 do_syscall_64+0xc9/0xf80 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f615df2c0d7

Allocated by task 9930:

Freed by task 64:

Last potentially related work creation:

The buggy address belongs to the object at ffff8881131e1000 which belongs to the cache kmalloc-cg-2k of size 2048 The buggy address is located 1168 bytes inside of freed 2048-byte region [ffff8881131e1000, ffff8881131e1800)

The buggy address belongs to the physical page: page_owner tracks the page as allocated page last free pid 9778 tgid 9778 stack trace:

Memory state around the buggy address: ffff8881131e1380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881131e1400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8881131e1480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8881131e1500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881131e1580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== [1]: https://gist.github.com/mrpre/f683f244544f7b11e7fa87df9e6c2eeb [2]: https://lore.kernel.org/linux-serial/[email protected]/T/#u

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
6%
KEV
Not listed

Published

May 27, 2026

Last Modified

June 25, 2026

Advisory Details (8)

Auto-updated Jun 25, 2026
No patch confirmed yet.
generic

serial: caif: fix use-after-free in caif_serial ldisc_close() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/d3c75db4e0460641dbcd274b40867e252d801da1
generic

serial: caif: fix use-after-free in caif_serial ldisc_close() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/c8c197aaa56b25a2d54f3aa07e27e228d6c08546
generic

serial: caif: fix use-after-free in caif_serial ldisc_close() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/5e266ba8d330d3b8e5bc198f238cd8901826cfa1
generic

serial: caif: fix use-after-free in caif_serial ldisc_close() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/52731ef4438155cea782fac74e547a327ab9e7c5
generic

serial: caif: fix use-after-free in caif_serial ldisc_close() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/4e63d6f68544ae5269ac9735ae5b69b59b5b8725
generic

serial: caif: fix use-after-free in caif_serial ldisc_close() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/40962f2bf8cdba63af23aec95ad3f49b689e58e2
generic

serial: caif: fix use-after-free in caif_serial ldisc_close() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/331e2b7051635780edea248dd08ae2026c126f4a
generic

serial: caif: fix use-after-free in caif_serial ldisc_close() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/308e7e4d0a846359685f40aade023aee7b27284c

Vendor Advisories for CVE-2026-45866(1)

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

Patch Availability(24)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulinux-tools-nvidia-lowlatency-64k-6.8 (6.8.0-1058.61.1) @ noble2026-08-25ubuntu
ubuntulinux-tools-lowlatency-hwe-20.04-edge (6.8.0-134.134.1) @ noble2026-08-25ubuntu
ubuntulinux-tools-nvidia-tegra-rt-6.8 (6.8.0-1029.30) @ noble2026-08-25ubuntu
ubuntulinux-tools-raspi-realtime-6.8 (6.8.0-2049.50) @ noble2026-08-25ubuntu
ubuntulinux-tools-raspi-6.8 (6.8.0-1060.64) @ noble2026-08-25ubuntu
ubuntulinux-virtual-6.8 (6.8.0-134.134) @ noble2026-08-25ubuntu
ubuntulinux-xilinx-zynqmp-tools-5.15.0-1075 (5.15.0-1075.79) @ jammy2026-08-25ubuntu
ubuntulinux-tools-azure-lts-24.04 (6.8.0-1063.71) @ noble2026-08-25ubuntu
ubuntulinux-tools-azure-fde-lts-24.04 (6.8.0-1062.69) @ noble2026-08-25ubuntu
ubuntulinux-tools-fips-6.8 (6.8.0-134.134+fips1) @ noble2026-08-25ubuntu
ubuntulinux-tools-gcp-edge (5.15.0.1112.122~20.04.1) @ focal2026-08-25ubuntu
ubuntulinux-tools-oracle-edge (5.15.0.1109.115~20.04.1) @ focal2026-08-25ubuntu
ubuntulinux-tools-intel-iotg-5.15 (5.15.0.1107.106) @ jammy2026-08-25ubuntu
ubuntulinux-tools-nvidia-tegra-rt-5.15 (5.15.0.1064.66~20.04.1) @ focal2026-08-25ubuntu
ubuntulinux-tools-nvidia-lowlatency-5.15 (5.15.0.1107.107) @ jammy2026-08-25ubuntu
ubuntulinux-tools-nvidia-tegra-rt-5.15 (5.15.0.1064.64) @ jammy2026-08-25ubuntu
ubuntulinux-tools-azure-fde-6.8 (6.8.0-1062.69~22.04.1) @ jammy2026-08-25ubuntu
ubuntulinux-tools-oracle-lts-22.04 (5.15.0.1109.105) @ jammy2026-08-25ubuntu
ubuntulinux-tools-azure-fde-lts-22.04 (5.15.0.1117.126) @ jammy2026-08-25ubuntu
ubuntulinux-virtual-hwe-22.04-edge (6.8.0-136.136~22.04.1) @ jammy2026-08-25ubuntu
ubuntulinux-tools-azure-fips-5.15 (5.15.0.1117.102) @ jammy2026-08-25ubuntu
ubuntulinux-tools-intel-iot-realtime-5.15 (5.15.0.1104.108) @ jammy2026-08-25ubuntu
ubuntulinux-xilinx-zynqmp (6.8.0.1032.33) @ noble2026-08-25ubuntu
linuxKernel @ 5.10.252—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

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
linux5.10.103-1 ... 5.10.92-2 (53 versions)5.10.257-1—
Debian:12(1)
PackageVulnerable rangeFixed inDependents
linux6.1.106-1 ... 6.1.99-1 (48 versions)6.1.170-1—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
linux6.12.38-1 ... 6.12.85-1~bpo12+1 (17 versions)6.12.85-1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
linux6.12.100-1 ... 6.18~rc7-1~exp1 (100 versions)6.18.14-1—

Weakness Classification(1)

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

All Vendor Advisories

(23)

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 4× in last 7d / 83× 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 209 total refreshes for this CVE.

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

Related CVEs(same product + same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-45866?
CVE-2026-45866 is a high vulnerability published on May 27, 2026. In the Linux kernel, the following vulnerability has been resolved: serial: caif: fix use-after-free in caifserial ldiscclose() There is a use-after-free bug in caifserial where handletx() may access ser->tty after the tty has been freed. The race condition occurs between ldisc_close() and packet…
When was CVE-2026-45866 disclosed?
CVE-2026-45866 was first published in the National Vulnerability Database on May 27, 2026, with the most recent update on June 25, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-45866 actively exploited?
CVE-2026-45866 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 94.1% of all scored CVEs.
What is the CVSS score of CVE-2026-45866?
CVE-2026-45866 has a CVSS v3 base score of 7.8 (NVD).
How do I remediate CVE-2026-45866?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-45866, 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

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-45866

Explore →

Is Your Infrastructure Affected by CVE-2026-45866?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs