CVE-2026-23115: Linux kernel · serial: Fix not set tty->port race condition
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 4.7 Medium · fixed in 6.17.0-1021.21~24.04.1 : update Linux kernel when convenient.
Data as of 26 Oct 2026, 12:55 UTC
- EPSS
- 0.08% chance of exploitation in 30 days – higher than 0% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 6.17.0-1021.21~24.04.1, 6.17.0-1021.24~24.04.1, 6.17.0-41.41~24.04.1 +3
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 14 Feb 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Patches and advisories
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 25.10linuxpkg:deb/ubuntu/linux?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-oraclepkg:deb/ubuntu/linux-oracle?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
In the Linux kernel, the following vulnerability has been resolved: serial: Fix not set tty->port race condition Revert commit bfc467db60b7 ("serial: remove redundant tty_port_link_device()") because the tty_port_link_device() is not redundant: the tty->port has to be confured before we call uart_configure_port(), otherwise user-space can open console without TTY linked to the driver. This tty_port_link_device() was added explicitly to avoid this exact issue in commit fb2b90014d78 ("tty: link tty and port before configuring it as console"), so offending commit basically reverted the fix saying it is redundant without addressing the actual race condition presented there. Reproducible always as tty->port warning on Qualcomm SoC with most of devices disabled, so with very fast boot, and one serial device being the console: printk: legacy console [ttyMSM0] enabled printk: legacy console [ttyMSM0] enabled printk: legacy bootconsole [qcom_geni0] disabled printk: legacy bootconsole [qcom_geni0] disabled ------------[ cut here ]------------ tty_init_dev: ttyMSM driver does not set tty->port. This would crash the kernel. Fix the driver! WARNING: drivers/tty/tty_io.c:1414 at tty_init_dev.part.0+0x228/0x25c, CPU#2: systemd/1 Modules linked in: socinfo tcsrcc_eliza gcc_eliza sm3_ce fuse ipv6 CPU: 2 UID: 0 PID: 1 Comm: systemd Tainted: G S 6.19.0-rc4-next-20260108-00024-g2202f4d30aa8 #73 PREEMPT Tainted: [S]=CPU_OUT_OF_SPEC Hardware name: Qualcomm Technologies, Inc. Eliza (DT) ... tty_init_dev.part.0 (drivers/tty/tty_io.c:1414 (discriminator 11)) (P) tty_open (arch/arm64/include/asm/atomic_ll_sc.h:95 (discriminator 3) drivers/tty/tty_io.c:2073 (discriminator 3) drivers/tty/tty_io.c:2120 (discriminator 3)) chrdev_open (fs/char_dev.c:411) do_dentry_open (fs/open.c:962) vfs_open (fs/open.c:1094) do_open (fs/namei.c:4634) path_openat (fs/namei.c:4793) do_filp_open (fs/namei.c:4820) do_sys_openat2 (fs/open.c:1391 (discriminator 3)) ... Starting Network Name Resolution... Apparently the flow with this small Yocto-based ramdisk user-space is: driver (qcom_geni_serial.c): user-space: ============================ =========== qcom_geni_serial_probe() uart_add_one_port() serial_core_register_port() serial_core_add_one_port() uart_configure_port() register_console() | | open console | ... | tty_init_dev() | driver->ports[idx] is NULL | tty_port_register_device_attr_serdev() tty_port_link_device() <- set driver->ports[idx]
References
- ubuntu.com/security/CVE-2026-23115 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-23115 (opens in a new tab)
- git.kernel.org/linus/32f37e57583f869140cff445feedeea8a5fea986 (opens in a new tab)
- git.kernel.org/stable/c/2501c49306238b54a2de0f93de43d50ab6e76c84 (opens in a new tab)
- git.kernel.org/stable/c/32f37e57583f869140cff445feedeea8a5fea986 (opens in a new tab)
- ubuntu.com/security/notices/USN-8570-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8594-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8604-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8605-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8570-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8669-1 (opens in a new tab)