CVE-2026-42300: Github.com/l3montree dev/devguard DevGuard Has An Unauthenticated Identity Vulnerability

CRITICAL
Advisory Identifier: GHSA-2g9v-7mr5-fgjg
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CWE-288
Published
Advisory Summary

CVE-2026-42300 is a CRITICAL devguard has an unauthenticated identity vulnerability (CWE-288: Authentication Bypass Using an Alternate Path or Channel) affecting Github.com/l3montree dev/devguard libraries in the Go ecosystem. The issue involves devguard has an unauthenticated identity assertion via `x-admin-token` header. Remediation is available by upgrading affected packages to version 1.2.2.

CVE-2026-42300 at a Glance

CVE Identifier CVE-2026-42300
GHSA Identifier GHSA-2g9v-7mr5-fgjg
Severity CRITICAL
CVSS v3.1 Base Score N/A
CWE Classification CWE-288: Authentication Bypass Using an Alternate Path or Channel
Affected Product Github.com/l3montree dev/devguard
Package Ecosystem Go
Published Date
Last Updated

How to Fix CVE-2026-42300

To remediate this vulnerability, upgrade all affected Github.com/l3montree dev/devguard dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

github.com/l3montree-dev/devguard fixed: 1.2.2 
Upgrade github.com/l3montree-dev/devguard to 1.2.2
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for github.com/l3montree-dev/devguard

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-42300, inspect your project dependencies for Github.com/l3montree dev/devguard:

inspect dependencies for github.com/l3montree-dev/devguard

Analyze the terminal output to locate any version of Github.com/l3montree dev/devguard in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.2.2), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-288: Authentication Bypass Using an Alternate Path or Channel, where the product requires authentication, but the product has an alternate path or channel that does not require authentication. In Github.com/l3montree dev/devguard, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Impact The `SessionMiddleware` accepts a client-supplied `X-Admin-Token` HTTP request header and uses its raw string value as the authenticated `userID` when no Kratos session cookie is present. An unauthenticated attacker who knows or can guess a target user's Kratos identity UUID can issue requests as that user. Where the target user is an organisation `admin` or `owner`, this gives the attacker full control over that organisation's DevGuard resources. ### Patches The release v1.2.2 patches this issue. Update your DevGuard API Instances to this version. ### Workarounds Configure a reverse proxy to strip the `X-Admin-Token` header before sending requests to the DevGuard API. ### Resources Fixed commit: https://github.com/l3montree-dev/devguard/commit/6f38310bf93b2a63df3055038f4da82b1f4e6d9a

CVE-2026-42300 Affected Github.com/l3montree dev/devguard Versions

1 component(s)
Fixed Versions:
1.2.2
Product / Package Ecosystem Affected Versions Fixed Version
github.com/l3montree-dev/devguard
golang/github.com/l3montree-dev/devguard
Go
< 1.2.2
1.2.2

References

GitHub Advisory / Wiki ADVISORY
https://github.com/l3montree-dev/devguard/security/advisories/GHSA-2g9v-7mr5-fgjg
NVD — CVE-2026-42300 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-42300
Security Fix Commit FIX COMMIT
https://github.com/l3montree-dev/devguard/commit/6f38310bf93b2a63df3055038f4da82b1f4e6d9a
Github.com/l3montree dev/devguard Source Repository REPOSITORY
https://github.com/l3montree-dev/devguard

Frequently Asked Questions

What is CVE-2026-42300?
CVE-2026-42300 is a security vulnerability in Github.com/l3montree dev/devguard involving DevGuard has an unauthenticated identity assertion via `X-Admin-Token` header under CWE-288: Authentication Bypass Using an Alternate Path or Channel.
Which Github.com/l3montree dev/devguard versions are affected?
Affected versions include releases prior to 1.2.2 across affected packages: github.com/l3montree-dev/devguard.
What version fixes CVE-2026-42300?
Upgrading to 1.2.2 (or the latest patched release for your respective branch) resolves the vulnerability.
Is github.com/l3montree-dev/devguard affected?
Yes, github.com/l3montree-dev/devguard is affected in releases prior to 1.2.2. Upgrade your dependency to 1.2.2 or later.
What CWE is associated with CVE-2026-42300?
CVE-2026-42300 is classified under CWE-288: Authentication Bypass Using an Alternate Path or Channel (The product requires authentication, but the product has an alternate path or channel that does not require authentication.).
How can I check Go dependencies for CVE-2026-42300?
Run the dependency tree command: 'inspect dependencies for github.com/l3montree-dev/devguard'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-2g9v-7mr5-fgjg",
  "modified" : "2026-05-13T16:26:37Z",
  "published" : "2026-05-05T20:58:27Z",
  "aliases" : [ "CVE-2026-42300" ],
  "summary" : "DevGuard has an unauthenticated identity assertion via `X-Admin-Token` header",
  "details" : "### Impact\nThe `SessionMiddleware` accepts a client-supplied `X-Admin-Token` HTTP request header and uses its raw string value as the authenticated `userID` when no Kratos session cookie is present. An unauthenticated attacker who knows or can guess a target user's Kratos identity UUID can issue requests as that user. Where the target user is an organisation `admin` or `owner`, this gives the attacker full control over that organisation's DevGuard resources.\n\n### Patches\nThe release v1.2.2 patches this issue. Update your DevGuard API Instances to this version.\n\n### Workarounds\nConfigure a reverse proxy to strip the `X-Admin-Token` header before sending requests to the DevGuard API.\n\n### Resources\nFixed commit: https://github.com/l3montree-dev/devguard/commit/6f38310bf93b2a63df3055038f4da82b1f4e6d9a",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/l3montree-dev/devguard"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.2.2"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/l3montree-dev/devguard/security/advisories/GHSA-2g9v-7mr5-fgjg"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-42300"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/l3montree-dev/devguard/commit/6f38310bf93b2a63df3055038f4da82b1f4e6d9a"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/l3montree-dev/devguard"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-288" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-05T20:58:27Z",
    "nvd_published_at" : "2026-05-12T18:17:24Z"
  }
}