Vulnerability-Lookup

CVE-2026-52824 (GCVE-0-2026-52824)

Vulnerability from cvelistv5 – Published: 2026-09-15 10:40 – Updated: 2026-09-16 17:33

Title

Kimai: Default APP_SECRET in Docker Image Enables Cookie Forgery and Account Takeover

Summary

Kimai is an open-source time tracking application. Prior to 2.58.0, the official Docker image sets APP_SECRET to the public value change_this_to_something_unique in Dockerfile, and .docker/entrypoint.sh neither replaces nor rejects that value before Symfony uses it as kernel.secret. An unauthenticated attacker who reaches a deployment that did not override APP_SECRET, knows a username, correctly guesses the account ID associated with that username, and targets an account without active two-factor authentication can forge HMAC-protected authentication artifacts, including KIMAI_REMEMBER cookies and login links, to access the account without its password. The updated entrypoint generates and persists a random secret when no safe operator-provided value exists. This issue is fixed in version 2.58.0.

Severity

9.1 (Critical)


                        
                          CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

SSVC

Exploitation: none Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-16 17:32 UTC

CWE

CWE-1188 - Insecure Default Initialization of Resource

Assigner

GitHub_M CNA under the mitre root

CNA scorecard C 72/100 over 7771 records in the last 180 days details

References

5 references

URL	Tags
https://github.com/kimai/kimai/security/advisorie…	x_refsource_CONFIRM
https://github.com/kimai/kimai/pull/5952	x_refsource_MISC
https://github.com/kimai/kimai/commit/31a8f887a5c…	x_refsource_MISC
https://github.com/kimai/kimai/releases/tag/2.58.0	x_refsource_MISC
https://www.kimai.org/en/security/ghsa-jr9p-4h4j-6c58	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
kimai	kimai	Affected: < 2.58.0	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-52824

Vulnerability from fkie_nvd - Published: 2026-09-15 11:17 - Updated: 2026-09-30 17:51

Severity

9.1 (Critical) - CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/kimai/kimai/commit/31a8f887a5cda517db7b4320a7ad997c87d08601
	security-advisories@github.com	https://github.com/kimai/kimai/pull/5952
	security-advisories@github.com	https://github.com/kimai/kimai/releases/tag/2.58.0
	security-advisories@github.com	https://github.com/kimai/kimai/security/advisories/GHSA-jr9p-4h4j-6c58
	security-advisories@github.com	https://www.kimai.org/en/security/ghsa-jr9p-4h4j-6c58

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
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    {
      "affectedData": [
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          "product": "kimai",
          "vendor": "kimai",
          "versions": [
            {
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  "metrics": {
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      "url": "https://github.com/kimai/kimai/releases/tag/2.58.0"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/kimai/kimai/security/advisories/GHSA-jr9p-4h4j-6c58"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://www.kimai.org/en/security/ghsa-jr9p-4h4j-6c58"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-1188"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

GHSA-JR9P-4H4J-6C58

Vulnerability from github – Published: 2026-07-14 00:07 – Updated: 2026-07-14 00:07

Summary

Kimai: Default APP_SECRET in Docker Image Enables Cookie Forgery and Account Takeover

Details

Summary

The official Kimai Docker image ships with APP_SECRET=change_this_to_something_unique as the default environment variable. The Docker entrypoint does not override or validate this value. Any Kimai instance deployed using the Docker image without explicitly setting APP_SECRET runs with a publicly-known Symfony kernel.secret, enabling an unauthenticated attacker to forge HMAC-signed cookies and login links to take over any account including super_admin.

Details

Dockerfile:263 sets ENV APP_SECRET=change_this_to_something_unique. This value is consumed by config/packages/framework.yaml:7 as kernel.secret, which Symfony uses to HMAC-sign:

The KIMAI_REMEMBER remember-me cookie
LoginLink signatures
Password reset URLs
CSRF tokens

The .docker/entrypoint.sh does not check for or replace the default sentinel value. The bare-metal .env.dist:38 ships the same default. No startup-time guard exists anywhere in the codebase that refuses to start when APP_SECRET equals the sentinel.

User IDs are sequential integers starting from 1. The first super_admin account is almost always id=1. User IDs are visible in some URLs and API responses.

A PoC was provided, but removed for security reasons.

Impact

Any Kimai instance deployed via the official Docker image without overriding APP_SECRET can be compromised from the internet. An unauthenticated attacker who can reach the Kimai URL can forge authentication tokens and log in as any user if: - a username is known AND - the correct account ID for this username is guessed AND - the account has no active 2FA (two factor) authentication

Solution

The entrypoint.sh file is updated and now contains a script that generates a random APP_SECRET via bin2hex(random_bytes(32)) which will be stored in /opt/kimai/var/data/.appsecret
The entrypoint.sh will create the file /opt/kimai/.env.local containing the APP_SECRET, either fetched from the Docker Environment or from the newly created secret file
The documentation was updated to highlight the importance of using a random secret for APP_SECRET
The Dockerfile removed default APP_SECRET=change_this_to_something_unique
Login links now contain more entropy (see GHSA-m492-gv72-xvxj) - so even without all previous changes, attackers won't be able to generate Login links even for installations that have a hard-coded APP_SECRET=change_this_to_something_unique

See https://www.kimai.org/en/security/ghsa-jr9p-4h4j-6c58 for more information.

Severity

9.1 (Critical)


                  
                    CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 2.57.0"
      },
      "package": {
        "ecosystem": "Packagist",
        "name": "kimai/kimai"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.58.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-52824"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1188"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-14T00:07:59Z",
    "nvd_published_at": null,
    "severity": "CRITICAL"
  },
  "details": "### Summary\n\nThe official Kimai Docker image ships with `APP_SECRET=change_this_to_something_unique` as the default environment variable. The Docker entrypoint does not override or validate this value. Any Kimai instance deployed using the Docker image without explicitly setting `APP_SECRET` runs with a publicly-known Symfony `kernel.secret`, enabling an unauthenticated attacker to forge HMAC-signed cookies and login links to take over any account including super_admin.\n\n### Details\n\n`Dockerfile:263` sets `ENV APP_SECRET=change_this_to_something_unique`. This value is consumed by `config/packages/framework.yaml:7` as `kernel.secret`, which Symfony uses to HMAC-sign:\n\n- The `KIMAI_REMEMBER` remember-me cookie\n- LoginLink signatures\n- Password reset URLs\n- CSRF tokens\n\nThe `.docker/entrypoint.sh` does not check for or replace the default sentinel value. The bare-metal `.env.dist:38` ships the same default. No startup-time guard exists anywhere in the codebase that refuses to start when `APP_SECRET` equals the sentinel.\n\nUser IDs are sequential integers starting from 1. The first super_admin account is almost always `id=1`. User IDs are visible in some URLs and API responses.\n\n*A PoC was provided, but removed for security reasons.*\n\n### Impact\n\nAny Kimai instance deployed via the official Docker image without overriding `APP_SECRET` can be compromised from the internet. An unauthenticated attacker who can reach the Kimai URL can forge authentication tokens and log in as any user if:\n- a username is known AND\n- the correct account ID for this username is guessed AND\n- the account has no active 2FA (two factor) authentication\n\n## Solution\n\n- The entrypoint.sh file is updated and now contains a script that generates a random `APP_SECRET` via `bin2hex(random_bytes(32))` which will be stored in  `/opt/kimai/var/data/.appsecret`\n- The entrypoint.sh will create the file `/opt/kimai/.env.local` containing the `APP_SECRET`, either fetched from the Docker Environment or from the newly created secret file\n- The documentation was updated to highlight the importance of using a random secret for `APP_SECRET`\n- The Dockerfile removed default `APP_SECRET=change_this_to_something_unique`\n- Login links now contain more entropy (see GHSA-m492-gv72-xvxj) - so even without all previous changes, attackers won\u0027t be able to generate Login links even for installations that have a hard-coded `APP_SECRET=change_this_to_something_unique`\n\nSee [https://www.kimai.org/en/security/ghsa-jr9p-4h4j-6c58](https://www.kimai.org/en/security/ghsa-jr9p-4h4j-6c58) for more information.",
  "id": "GHSA-jr9p-4h4j-6c58",
  "modified": "2026-07-14T00:07:59Z",
  "published": "2026-07-14T00:07:59Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/kimai/kimai/security/advisories/GHSA-jr9p-4h4j-6c58"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/kimai/kimai"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Kimai: Default APP_SECRET in Docker Image Enables Cookie Forgery and Account Takeover"
}

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CVE-2026-52824 (GCVE-0-2026-52824)

FKIE_CVE-2026-52824

GHSA-JR9P-4H4J-6C58

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