CyberSecBulletin
CVE-2026-63830NVD status: Analyzed

Linux: Incorrect Authorization

Published Updated By the CyberSecBulletin desk

CVE-2026-63830 is a critical-severity incorrect authorization vulnerability in Linux, with a CVSS 3.1 base score of 9.4 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions f126eed589eec6f201405abbc398844042ef6d57, 31a110642b5fb5e61940cbcfb503445ac4f28017, 9bb86d8184b37503816150c4a6ad3c17dfdbe827 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 0.44% chance of exploitation within 30 days, which is low compared with other CVEs.

Patch this week

Critical severity: a successful attack would have severe impact.

What to do

  1. Update Linux to f126eed589eec6f201405abbc398844042ef6d57 or 31a110642b5fb5e61940cbcfb503445ac4f28017 or 9bb86d8184b37503816150c4a6ad3c17dfdbe827 or 0eb4c16c4adb262763bda870a8ed38a1a9dec7ec, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.10.261 or 5.15.212 or 6.1.177 or 6.6.144, whichever matches your release line, or a later version.
  3. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxd3b18ad31f93d0b6bae105c679018a1ba7daa9ca up to, but not including, f126eed589eec6f201405abbc398844042ef6d57; d3b18ad31f93d0b6bae105c679018a1ba7daa9ca up to, but not including, 31a110642b5fb5e61940cbcfb503445ac4f28017; d3b18ad31f93d0b6bae105c679018a1ba7daa9ca up to, but not including, 9bb86d8184b37503816150c4a6ad3c17dfdbe827; d3b18ad31f93d0b6bae105c679018a1ba7daa9ca up to, but not including, 0eb4c16c4adb262763bda870a8ed38a1a9dec7ec; d3b18ad31f93d0b6bae105c679018a1ba7daa9ca up to, but not including, d22cc92bc41290e5783a72375e0843d9435f6001; d3b18ad31f93d0b6bae105c679018a1ba7daa9ca up to, but not including, 1acdd14c0990dd1cd4b6534f00366d2e6dfce05f; d3b18ad31f93d0b6bae105c679018a1ba7daa9ca up to, but not including, 21ed9540a8e1906dfcbc1bb82ba9b4de4fa4bd6d; d3b18ad31f93d0b6bae105c679018a1ba7daa9ca up to, but not including, 406e8a651a7b854c41fecd5117bb282b3a6c2c6b; and 1 more rangesf126eed589eec6f201405abbc398844042ef6d57, 31a110642b5fb5e61940cbcfb503445ac4f28017, 9bb86d8184b37503816150c4a6ad3c17dfdbe827, 0eb4c16c4adb262763bda870a8ed38a1a9dec7ec, d22cc92bc41290e5783a72375e0843d9435f6001, 1acdd14c0990dd1cd4b6534f00366d2e6dfce05f
LinuxLinux Kernel4.20 up to, but not including, 5.10.261; 5.11 up to, but not including, 5.15.212; 5.16 up to, but not including, 6.1.177; 6.2 up to, but not including, 6.6.144; 6.7 up to, but not including, 6.12.95; 6.13 up to, but not including, 6.18.38; 6.19 up to, but not including, 7.1.35.10.261, 5.15.212, 6.1.177, 6.6.144, 6.12.95, 6.18.38

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
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
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
HighData or code can be modified at will.
Availability
LowPerformance or availability is reduced.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L. Scored by CNA.

Official description

In the Linux kernel, the following vulnerability has been resolved: net: skmsg: preserve sg.copy across SG transforms The sk_msg sg.copy bitmap is part of the scatterlist entry ownership state. A set bit tells sk_msg_compute_data_pointers() not to expose the entry through writable BPF ctx->data. This protects entries backed by pages that are not private to the sk_msg, such as splice-backed file page-cache pages. Several sk_msg transform paths move, copy, split, or compact msg->sg.data[] entries without moving the matching sg.copy bit. This can make an externally backed entry arrive at a new slot with a clear copy bit. A later SK_MSG verdict can then expose sg_virt(sge) as writable ctx->data and BPF stores can modify the original page cache. Keep sg.copy synchronized with sg.data[] whenever entries are transferred, shifted, split, or copied into a new sk_msg. Clear the bit when an entry is replaced by a newly allocated private page or freed. This covers the BPF pull/push/pop helpers, sk_msg_shift_left/right(), sk_msg_xfer(), and tls_split_open_record(), including the partial tail entry created during TLS open-record splitting.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Incorrect Authorization

The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.

How developers prevent this class of flaw

  • Divide the product into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully mapping roles with data and functionality. Use role-based access control (RBAC) to enforce the roles at the appropriate boundaries. Note that this approach may not protect against horizontal authorization, i.e., it will not protect a user from attacking others with the same role.
  • Ensure that access control checks are performed related to the business logic. These checks may be different than the access control checks that are applied to more generic resources such as files, connections, processes, memory, and database records. For example, a database may restrict access for medical records to a specific database user, but each record might only be intended to be accessible to the patient and the patient's doctor.
  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using authorization frameworks such as the JAAS Authorization Framework and the OWASP ESAPI Access Control feature.

More Incorrect Authorization vulnerabilities (CWE-863)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Incorrect Authorization vulnerabilities

Spotted an error? Tell us.