Linux: Out-of-bounds Read
CVE-2026-63903 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 f1617539ab90e67da788959bfd314076f093a11a, f361359a952da15e70e693c2d7dca5c5843eae3e, 37e54d1b986df35c936d81e5b59a7aa3ec6938f0 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 f1617539ab90e67da788959bfd314076f093a11a or f361359a952da15e70e693c2d7dca5c5843eae3e or 37e54d1b986df35c936d81e5b59a7aa3ec6938f0 or ffb739a49186ea784bbd9cb91b647f062395b419, 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 | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, f1617539ab90e67da788959bfd314076f093a11a; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, f361359a952da15e70e693c2d7dca5c5843eae3e; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 37e54d1b986df35c936d81e5b59a7aa3ec6938f0; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, ffb739a49186ea784bbd9cb91b647f062395b419; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 6a4602221cba7a738442328d66a2f0b1c9bf6e17; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 22823a319fb2afdf02cacafbed8b613b757efbc8; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, db1e7eb6203d534dad64cac2c793b69e561e657b; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 4ce058df2ee02cc2a0f0fd5cd64ce6f1482a0b65; and 1 more ranges | f1617539ab90e67da788959bfd314076f093a11a, f361359a952da15e70e693c2d7dca5c5843eae3e, 37e54d1b986df35c936d81e5b59a7aa3ec6938f0, ffb739a49186ea784bbd9cb91b647f062395b419, 6a4602221cba7a738442328d66a2f0b1c9bf6e17, 22823a319fb2afdf02cacafbed8b613b757efbc8 |
| Linux | Linux Kernel | 2.6.12.1 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; 2.6.12; and 1 more ranges | 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: belkin_sa: validate interrupt status length The Belkin interrupt callback treats interrupt data as a four-byte status report and reads LSR/MSR fields at offsets 2 and 3. The interrupt-in buffer length is derived from endpoint wMaxPacketSize, and short interrupt transfers may complete successfully with a smaller actual_length. Check the completed interrupt packet length before parsing status fields so short interrupt endpoints and short successful packets are ignored instead of causing out-of-bounds or stale status-byte reads. KASAN report as below: BUG: KASAN: slab-out-of-bounds in belkin_sa_read_int_callback() Read of size 1 Call trace: belkin_sa_read_int_callback() (drivers/usb/serial/belkin_sa.c:202) __usb_hcd_giveback_urb() (drivers/usb/core/hcd.c:1630) dummy_timer() (?:?)
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/22823a319fb2afdf02cacafbed8b613b757efbc8
- git.kernel.org/stable/c/37e54d1b986df35c936d81e5b59a7aa3ec6938f0
- git.kernel.org/stable/c/4ce058df2ee02cc2a0f0fd5cd64ce6f1482a0b65
- git.kernel.org/stable/c/6a4602221cba7a738442328d66a2f0b1c9bf6e17
- git.kernel.org/stable/c/db1e7eb6203d534dad64cac2c793b69e561e657b
- git.kernel.org/stable/c/f1617539ab90e67da788959bfd314076f093a11a
- git.kernel.org/stable/c/f361359a952da15e70e693c2d7dca5c5843eae3e
- git.kernel.org/stable/c/ffb739a49186ea784bbd9cb91b647f062395b419
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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