CyberSecBulletin
CVE-2026-63829NVD status: Analyzed

Linux: Missing Authorization

Published Updated By the CyberSecBulletin desk

CVE-2026-63829 is a high-severity missing authorization vulnerability in Linux, with a CVSS 3.1 base score of 8.8 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 19275943d8fe903eb7b9aa53e380e41efd042ada, 866b0f5ae599490bd496fd84581c68ac8b94e6af, 92b766fc55156e0da2ecd0c2302c971118f8a229 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 0.15% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to 19275943d8fe903eb7b9aa53e380e41efd042ada or 866b0f5ae599490bd496fd84581c68ac8b94e6af or 92b766fc55156e0da2ecd0c2302c971118f8a229 or e54c05ed3d9c28733fb9e5837219aca3691defa3, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.10.261 or 5.15.212 or 6.1.178 or 6.6.145, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxb57708add31494175be741ed3fd24023b50c3423 up to, but not including, 19275943d8fe903eb7b9aa53e380e41efd042ada; b57708add31494175be741ed3fd24023b50c3423 up to, but not including, 866b0f5ae599490bd496fd84581c68ac8b94e6af; b57708add31494175be741ed3fd24023b50c3423 up to, but not including, 92b766fc55156e0da2ecd0c2302c971118f8a229; b57708add31494175be741ed3fd24023b50c3423 up to, but not including, e54c05ed3d9c28733fb9e5837219aca3691defa3; b57708add31494175be741ed3fd24023b50c3423 up to, but not including, 9831bc9ecb402957810c2045c663fbfe9b09e296; b57708add31494175be741ed3fd24023b50c3423 up to, but not including, 1697957eb0971d420dde42862b88eb43506a1105; b57708add31494175be741ed3fd24023b50c3423 up to, but not including, 47b5d3d506609b08b2e1f7c14f0b681a1953d572; b57708add31494175be741ed3fd24023b50c3423 up to, but not including, 8165f7ff57d9667d2bb477ef6af83ede7fed4ad7; and 1 more ranges19275943d8fe903eb7b9aa53e380e41efd042ada, 866b0f5ae599490bd496fd84581c68ac8b94e6af, 92b766fc55156e0da2ecd0c2302c971118f8a229, e54c05ed3d9c28733fb9e5837219aca3691defa3, 9831bc9ecb402957810c2045c663fbfe9b09e296, 1697957eb0971d420dde42862b88eb43506a1105
LinuxLinux Kernel3.16 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, 6.1.178; 6.2 up to, but not including, 6.6.145; 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, 6.1.178, 6.6.145, 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
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
ChangedThe attack can reach beyond the vulnerable component into other systems.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

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

Official description

In the Linux kernel, the following vulnerability has been resolved: net: ip_gre: require CAP_NET_ADMIN in the device netns for changelink A tunnel changelink() operates on at most two netns, dev_net(dev) and the tunnel link netns t->net. They differ once the device is created in or moved to a netns other than the one the request runs in. The rtnl changelink path checks CAP_NET_ADMIN only against dev_net(dev), so a caller privileged there but not in t->net can rewrite a tunnel that lives in t->net. Add rtnl_dev_link_net_capable() next to rtnl_get_net_ns_capable() in net/core/rtnetlink.c. It requires CAP_NET_ADMIN in the link netns and is skipped when the link netns is dev_net(dev), where the rtnl path already checked it. The other patches in this series use the same helper. Gate ipgre_changelink() and erspan_changelink() with it, at the top of the op before any attribute is parsed, because the parsers update live tunnel fields first. ipgre_netlink_parms() sets t->collect_md before ip_tunnel_changelink() runs. Commit 8b484efd5cb4 ("ip6: vti: Use ip6_tnl.net in vti6_siocdevprivate().") added the same check on the ioctl path. This adds it on RTM_NEWLINK.

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

The underlying weakness: Missing Authorization

The product does not perform an authorization check when an actor attempts to access a resource or perform an action.

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 Missing Authorization vulnerabilities (CWE-862)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Missing Authorization vulnerabilities

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