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CVE-2026-33898— Local Incus UI web server vulnerable to nuthentication bypass

Quick assessment

Affected
lxc incus
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Incus是LXC开源的一个系统容器和虚拟机管理器。 Incus 6.23.0之前版本存在授权问题漏洞，该漏洞源于身份验证令牌验证不当，可能导致本地攻击者获得与运行incus webui用户相同的Incus访问权限，进而导致权限提升或远程攻击者访问用户Incus实例及系统资源。

CVSS 8.8 · High EPSS 0.48% · P40

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application
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I. Basic Information for CVE-2026-33898

Vulnerability Information
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Vulnerability Title
Local Incus UI web server vulnerable to nuthentication bypass
Source: CVE Program / CVE List V5
Vulnerability Description
Incus is a system container and virtual machine manager. Prior to version 6.23.0, the web server spawned by `incus webui` incorrectly validates the authentication token such that an invalid value will be accepted. `incus webui` runs a local web server on a random localhost port. For authentication, it provides the user with a URL containing an authentication token. When accessed with that token, Incus creates a cookie persisting that token without needing to include it in subsequent HTTP requests. While the Incus client correctly validates the value of the cookie, it does not correctly validate the token when passed int the URL. This allows for an attacker able to locate and talk to the temporary web server on localhost to have as much access to Incus as the user who ran `incus webui`. This can lead to privilege escalation by another local user or an access to the user's Incus instances and possibly system resources by a remote attack able to trick the local user into interacting with the Incus UI web server. Version 6.23.0 patches the issue.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
认证机制不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
Incus 授权问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Incus是LXC开源的一个系统容器和虚拟机管理器。 Incus 6.23.0之前版本存在授权问题漏洞，该漏洞源于身份验证令牌验证不当，可能导致本地攻击者获得与运行incus webui用户相同的Incus访问权限，进而导致权限提升或远程攻击者访问用户Incus实例及系统资源。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
lxc incus < 6.23.0 -

II. Public POCs for CVE-2026-33898

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III. Intelligence Information for CVE-2026-33898

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Vendor Advisories for CVE-2026-33898 (1)

Same Patch Batch · lxc · 2026-03-26 · 6 CVEs total

CVE-2026-33897 10.0 CRITICAL Incus vulnerable to arbitrary file read and write through pongo templates
CVE-2026-33945 10.0 CRITICAL Abitrary file write through systemd-creds option
CVE-2026-33743 6.5 MEDIUM Incus vulnerable to denial of source through crafted bucket backup file
CVE-2026-33711 Incus vulnerable to local privilege escalation through VM screenshot path
CVE-2026-33542 Incus does not verify combined fingerprint when downloading images from simplestreams serv

IV. Related Vulnerabilities

Same product: incus
Same vendor: lxc
Same weakness: CWE-287

V. Comments for CVE-2026-33898

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