Linux: Out-of-bounds Read
CVE-2026-63902 is a high-severity out-of-bounds read vulnerability in Linux, with a CVSS 3.1 base score of 7.1 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions fcef31a5a85ccf3c313449a866ec6ed7e4132425, aaa66708bfb1dca2acd219d1c1582f9f6d5492cb, 44f9bab8df7750a1e2a4d6cc22d7c9c2dc096aed as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.17% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to fcef31a5a85ccf3c313449a866ec6ed7e4132425 or aaa66708bfb1dca2acd219d1c1582f9f6d5492cb or 44f9bab8df7750a1e2a4d6cc22d7c9c2dc096aed or be50533fe7068e86eb7adb81988e6d6a3f6dfe53, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.259 or 5.15.210 or 6.1.176 or 6.6.143, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 3416eaa1f8f8d516b77de514e14cf8da256d28fb up to, but not including, fcef31a5a85ccf3c313449a866ec6ed7e4132425; 3416eaa1f8f8d516b77de514e14cf8da256d28fb up to, but not including, aaa66708bfb1dca2acd219d1c1582f9f6d5492cb; 3416eaa1f8f8d516b77de514e14cf8da256d28fb up to, but not including, 44f9bab8df7750a1e2a4d6cc22d7c9c2dc096aed; 3416eaa1f8f8d516b77de514e14cf8da256d28fb up to, but not including, be50533fe7068e86eb7adb81988e6d6a3f6dfe53; 3416eaa1f8f8d516b77de514e14cf8da256d28fb up to, but not including, 90664556916de22467097d4c8ceb716d597a5c32; 3416eaa1f8f8d516b77de514e14cf8da256d28fb up to, but not including, ae03453f2c809ca3cf73753269fa6184dea7160f; 3416eaa1f8f8d516b77de514e14cf8da256d28fb up to, but not including, 4a4cb0021ebe1fcadb52e04d19ed8d71470a530b; 3416eaa1f8f8d516b77de514e14cf8da256d28fb up to, but not including, 9f9bfc80c67f35a275820da7e83a35dface08281; and 1 more ranges | fcef31a5a85ccf3c313449a866ec6ed7e4132425, aaa66708bfb1dca2acd219d1c1582f9f6d5492cb, 44f9bab8df7750a1e2a4d6cc22d7c9c2dc096aed, be50533fe7068e86eb7adb81988e6d6a3f6dfe53, 90664556916de22467097d4c8ceb716d597a5c32, ae03453f2c809ca3cf73753269fa6184dea7160f |
| Linux | Linux Kernel | 2.6.26 up to, but not including, 5.10.259; 5.11 up to, but not including, 5.15.210; 5.16 up to, but not including, 6.1.176; 6.2 up to, but not including, 6.6.143; 6.7 up to, but not including, 6.12.93; 6.13 up to, but not including, 6.18.35; 6.19 up to, but not including, 7.0.12; 7.1 | 5.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.93, 6.18.35 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H. Scored by NVD.
Official description
In the Linux kernel, the following vulnerability has been resolved: USB: serial: cypress_m8: validate interrupt packet headers cypress_read_int_callback() parses the interrupt-in buffer according to the selected Cypress packet format. Format 1 has a two-byte status/count header and format 2 has a one-byte combined status/count header. The usb-serial core sizes the interrupt-in buffer from the endpoint descriptor's wMaxPacketSize, and successful interrupt transfers can complete short when URB_SHORT_NOT_OK is not set. Check that the completed packet contains the selected header before reading it. Malformed short reports are ignored and the interrupt URB is resubmitted through the existing retry path, preventing out-of-bounds header-byte reads. KASAN report as below: KASAN slab-out-of-bounds in cypress_read_int_callback+0x240/0x7f0 Read of size 1 Call trace: cypress_read_int_callback() (drivers/usb/serial/cypress_m8.c:1009) __usb_hcd_giveback_urb() dummy_timer() [ johan: use constants in header length sanity checks ]
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Out-of-bounds Read
The product reads data past the end, or before the beginning, of the intended buffer.
How developers prevent this class of flaw
- Use a language that provides appropriate memory abstractions.
Timeline
- CVE record published.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/44f9bab8df7750a1e2a4d6cc22d7c9c2dc096aed
- git.kernel.org/stable/c/4a4cb0021ebe1fcadb52e04d19ed8d71470a530b
- git.kernel.org/stable/c/90664556916de22467097d4c8ceb716d597a5c32
- git.kernel.org/stable/c/9f9bfc80c67f35a275820da7e83a35dface08281
- git.kernel.org/stable/c/aaa66708bfb1dca2acd219d1c1582f9f6d5492cb
- git.kernel.org/stable/c/ae03453f2c809ca3cf73753269fa6184dea7160f
- git.kernel.org/stable/c/be50533fe7068e86eb7adb81988e6d6a3f6dfe53
- git.kernel.org/stable/c/fcef31a5a85ccf3c313449a866ec6ed7e4132425
Recent Out-of-bounds Read vulnerabilities
- 7.1 High severity
- 7.8 High severity
- 7.3 High severity
- 7.1 High severity
- 7.8 High severity
- 9.8 Critical severity
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