In the Linux kernel, the following vulnerability has been resolved: ppp: require CAP_NET_ADMIN in target netns for unattached ioctls /dev/ppp open… (CVE-2026-53075)
In the Linux kernel, the following vulnerability has been resolved: ppp: require CAP_NET_ADMIN in target netns for unattached ioctls /dev/ppp open is currently authorized against file->f_cred->user_ns, while unattached administrative ioctls operate on current->nsproxy->net_ns. As a result, a local unprivileged user can create a new user namespace with CLONE_NEWUSER, gain CAP_NET_ADMIN only in that new user namespace, and still issue PPPIOCNEWUNIT, PPPIOCATTACH, or PPPIOCATTCHAN against an inherited network namespace. Require CAP_NET_ADMIN in the user namespace that owns the target network namespace before handling unattached PPP administrative ioctls. This preserves normal pppd operation in the network namespace it is actually privileged in, while rejecting the userns-only inherited-netns case.
AI Analysis
Technical Summary
The Linux kernel's PPP ioctl authorization was flawed because it checked CAP_NET_ADMIN against the user namespace of the file descriptor's credentials, whereas the ioctls operated on the current network namespace. This discrepancy allowed a local unprivileged user to create a new user namespace with CAP_NET_ADMIN and issue administrative PPP ioctls against an inherited network namespace without proper authorization. The vulnerability affects kernel versions prior to 5.15.0-1112.119~20.04.1, 5.15.0-1117.126~20.04.1, 5.15.0-1117.126~20.04.2, 5.15.0-186.196~20.04.1, and 5.15.0-1106.110~20.04.1. The fix requires CAP_NET_ADMIN in the user namespace owning the target network namespace before handling unattached PPP administrative ioctls, ensuring correct privilege enforcement.
Potential Impact
A local unprivileged user could escalate privileges within network namespaces by exploiting the improper capability check, potentially allowing unauthorized administrative operations on PPP interfaces. This could lead to unauthorized network configuration changes or interference with PPP network interfaces within the affected namespaces.
Mitigation Recommendations
A fix is available in Linux kernel versions 5.15.0-1112.119~20.04.1 and later (including 5.15.0-1117.126~20.04.1, 5.15.0-1117.126~20.04.2, 5.15.0-186.196~20.04.1, and 5.15.0-1106.110~20.04.1). Users should upgrade to these or later kernel versions to remediate this vulnerability. No additional mitigation steps are indicated beyond applying the official kernel updates.
In the Linux kernel, the following vulnerability has been resolved: ppp: require CAP_NET_ADMIN in target netns for unattached ioctls /dev/ppp open… (CVE-2026-53075)
Description
In the Linux kernel, the following vulnerability has been resolved: ppp: require CAP_NET_ADMIN in target netns for unattached ioctls /dev/ppp open is currently authorized against file->f_cred->user_ns, while unattached administrative ioctls operate on current->nsproxy->net_ns. As a result, a local unprivileged user can create a new user namespace with CLONE_NEWUSER, gain CAP_NET_ADMIN only in that new user namespace, and still issue PPPIOCNEWUNIT, PPPIOCATTACH, or PPPIOCATTCHAN against an inherited network namespace. Require CAP_NET_ADMIN in the user namespace that owns the target network namespace before handling unattached PPP administrative ioctls. This preserves normal pppd operation in the network namespace it is actually privileged in, while rejecting the userns-only inherited-netns case.
CVSS v3.1
Score 8.8high
Affected software
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protected]~16.04.1?arch=source&distro=esm-infra-legacy/xenialpkg:deb/ubuntu/[email protected]?arch=source&distro=fips-updates/xenialpkg:deb/ubuntu/[email protected]?arch=source&distro=fips/xenialpkg:deb/ubuntu/[email protected]?arch=source&distro=esm-infra/bionicpkg:deb/ubuntu/[email protected]?arch=source&distro=esm-infra/bionicpkg:deb/ubuntu/[email protected]?arch=source&distro=bionicpkg:deb/ubuntu/[email protected]?arch=source&distro=bionicpkg:deb/ubuntu/[email protected]~18.04.1?arch=source&distro=esm-infra/bionicpkg:deb/ubuntu/[email protected]?arch=source&distro=bionicpkg:deb/ubuntu/[email protected]?arch=source&distro=esm-infra/bionicpkg:deb/ubuntu/[email protected]?arch=source&distro=bionicpkg:deb/ubuntu/[email protected]~18.04.1?arch=source&distro=esm-infra/bionicpkg:deb/ubuntu/[email protected]~18.04.2?arch=source&distro=bionicpkg:deb/ubuntu/[email protected]?arch=source&distro=bionicpkg:deb/ubuntu/[email protected]?arch=source&distro=esm-infra/bionicpkg:deb/ubuntu/[email 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protected]?arch=source&distro=resolutepkg:deb/ubuntu/[email protected]?arch=source&distro=resolutepkg:deb/ubuntu/[email protected]?arch=source&distro=resolutepkg:deb/ubuntu/[email protected]?arch=source&distro=resolutepkg:deb/ubuntu/[email protected]?arch=source&distro=resolutepkg:deb/ubuntu/[email protected]?arch=source&distro=resolutepkg:deb/ubuntu/[email protected]?arch=source&distro=resolutepkg:deb/ubuntu/[email protected]?arch=source&distro=resoluteRun on your own infrastructure? 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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The Linux kernel's PPP ioctl authorization was flawed because it checked CAP_NET_ADMIN against the user namespace of the file descriptor's credentials, whereas the ioctls operated on the current network namespace. This discrepancy allowed a local unprivileged user to create a new user namespace with CAP_NET_ADMIN and issue administrative PPP ioctls against an inherited network namespace without proper authorization. The vulnerability affects kernel versions prior to 5.15.0-1112.119~20.04.1, 5.15.0-1117.126~20.04.1, 5.15.0-1117.126~20.04.2, 5.15.0-186.196~20.04.1, and 5.15.0-1106.110~20.04.1. The fix requires CAP_NET_ADMIN in the user namespace owning the target network namespace before handling unattached PPP administrative ioctls, ensuring correct privilege enforcement.
Potential Impact
A local unprivileged user could escalate privileges within network namespaces by exploiting the improper capability check, potentially allowing unauthorized administrative operations on PPP interfaces. This could lead to unauthorized network configuration changes or interference with PPP network interfaces within the affected namespaces.
Mitigation Recommendations
A fix is available in Linux kernel versions 5.15.0-1112.119~20.04.1 and later (including 5.15.0-1117.126~20.04.1, 5.15.0-1117.126~20.04.2, 5.15.0-186.196~20.04.1, and 5.15.0-1106.110~20.04.1). Users should upgrade to these or later kernel versions to remediate this vulnerability. No additional mitigation steps are indicated beyond applying the official kernel updates.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- UBUNTU-CVE-2026-53075
- Osv Schema Version
- 1.7.0
- Aliases
- []
- Ecosystems
- ["Ubuntu:Pro:14.04:LTS","Ubuntu:Pro:16.04:LTS","Ubuntu:16.04:LTS","Ubuntu:Pro:FIPS:16.04:LTS","Ubuntu:Pro:18.04:LTS","Ubuntu:18.04:LTS","Ubuntu:Pro:FIPS-updates:18.04:LTS","Ubuntu:Pro:FIPS:18.04:LTS","Ubuntu:Pro:20.04:LTS","Ubuntu:20.04:LTS","Ubuntu:Pro:FIPS-updates:20.04:LTS","Ubuntu:Pro:FIPS:20.04:LTS","Ubuntu:22.04:LTS","Ubuntu:Nvidia-BlueField:22.04:LTS","Ubuntu:Pro:FIPS-preview:22.04:LTS","Ubuntu:Pro:FIPS-updates:22.04:LTS","Ubuntu:Pro:Realtime:22.04:LTS","Ubuntu:24.04:LTS","Ubuntu:Nvidia-BlueField:24.04:LTS","Ubuntu:Pro:FIPS-updates:24.04:LTS","Ubuntu:Pro:Realtime:24.04:LTS","Ubuntu:25.10","Ubuntu:26.04:LTS"]
- Database Specific Severity
- null
- Cvss Version
- 4.0
Threat ID: 6a5a013991ae9bcd3f801ae9
Added to database: 07/17/2026, 10:17:29 UTC
Last enriched: 07/30/2026, 21:23:38 UTC
Last updated: 07/31/2026, 19:30:18 UTC
Views: 2
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