GHSA-6X44-W3XG-HQQF

Vulnerability from github – Published: 2026-05-19 20:04 – Updated: 2026-05-19 20:04
VLAI
Summary
Coder: PKCS#7 signature bypass in Azure instance identity allows unauthenticated agent token theft
Details

Summary

azureidentity.Validate() verifies that the PKCS#7 signer certificate chains to a trusted Azure CA but never verifies the PKCS#7 signature itself. An attacker can embed a legitimate Azure certificate alongside arbitrary content e.g. {"vmId":"<target>"} and the forged vmId will be accepted returning the victim workspace agent's session token.

No authentication is required. The attacker only needs to know a target VM's vmId which is a UUIDv4.

that's a practical limitation which would typically require prior access to be exploited

Root Cause

In unpatched Coder releases the signature over the PKCS#7 content is not validated - only the signing certificate is checked.

Impact

An attacker on any Azure VM or with access to a publicly available Azure IMDS certificate from CT logs can:

  1. Steal an agent session token by sending a forged PKCS#7 envelope to POST /api/v2/workspaceagents/azure-instance-identity which is unauthenticated.
  2. With the stolen token access:
  3. Git SSH private key via GET /workspaceagents/me/gitsshkey: push to repositories and impersonate the workspace owner.
  4. OAuth access tokens via GET /workspaceagents/me/external-auth: GitHub, GitLab, and Bitbucket tokens in plaintext.
  5. Workspace secrets via the agent manifest: environment variables, file paths, and API keys.

Attack Path Diagram

PKCS7_diagram (1)

Affected Versions

All versions of Coder v2 are affected.

Patches

Fixed in #25286

The fix was backported to all supported release lines:

Patched Versions
v2.33.3
v2.32.2
v2.31.12
v2.30.8
v2.29.13
v2.24.5

Workarounds

If unable to patch we recommend immediately reconfiguring any Azure templates to use token authentication rather than azure-instance-identity until the patch is released and you are fully upgraded.

  1. Modify the coder_agent.auth value to be token.
  2. Add CODER_AGENT_TOKEN=${coder_agent.main.token} to the set of environment variables for the Coder Workspace Agent initialization script.

Recognition

We'd like to thank Ben Tran of calif.io and Anthropic’s Security Team (ANT-2026-22445) for independently disclosing this issue!

Severity
9.1 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Show details on source website
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{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/coder/coder/v2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.33.0-rc.0"
            },
            {
              "fixed": "2.33.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/coder/coder/v2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.32.0-rc.0"
            },
            {
              "fixed": "2.32.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/coder/coder/v2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.31.0"
            },
            {
              "fixed": "2.31.12"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/coder/coder/v2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.30.0"
            },
            {
              "fixed": "2.30.8"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/coder/coder/v2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.29.0"
            },
            {
              "fixed": "2.29.13"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/coder/coder/v2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.24.5"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/coder/coder"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "0.27.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-46354"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-347"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-19T20:04:13Z",
    "nvd_published_at": null,
    "severity": "CRITICAL"
  },
  "details": "## Summary\n\n`azureidentity.Validate()` verifies that the PKCS#7 signer certificate chains to a trusted Azure CA but never verifies the PKCS#7 signature itself. An attacker can embed a legitimate Azure certificate alongside arbitrary content e.g. `{\"vmId\":\"\u003ctarget\u003e\"}` and the forged `vmId` will be accepted returning the victim workspace agent\u0027s session token.\n\n**No authentication is required.** The attacker only needs to know a target VM\u0027s `vmId` which is a `UUIDv4`.\n\u003e that\u0027s a practical limitation which would typically require prior access to be exploited\n\n## Root Cause\n\nIn unpatched Coder releases the signature over the PKCS#7 content is not validated - only the signing certificate is checked.\n\n## Impact\n\nAn attacker on any Azure VM or with access to a publicly available Azure IMDS certificate from CT logs can:\n\n1. **Steal an agent session token** by sending a forged PKCS#7 envelope to `POST /api/v2/workspaceagents/azure-instance-identity` which is unauthenticated.\n2. **With the stolen token** access:\n   - **Git SSH private key** via `GET /workspaceagents/me/gitsshkey`: push to repositories and impersonate the workspace owner.\n   - **OAuth access tokens** via `GET /workspaceagents/me/external-auth`: GitHub, GitLab, and Bitbucket tokens in plaintext.\n   - **Workspace secrets** via the agent manifest: environment variables, file paths, and API keys.\n\n## Attack Path Diagram\n\n\u003cimg width=\"5588\" height=\"4176\" alt=\"PKCS7_diagram (1)\" src=\"https://github.com/user-attachments/assets/74e88a89-a995-450d-87ab-6feed03579a5\" /\u003e\n\n## Affected Versions\n\nAll versions of Coder v2 are affected.\n\n## Patches\n\nFixed in [#25286 ](https://github.com/coder/coder/pull/25286)\n\nThe fix was backported to all supported release lines:\n\n| Patched Versions |\n| --- |\n| [**v2.33.3**](https://github.com/coder/coder/releases/tag/v2.33.3) |\n| [**v2.32.2**](https://github.com/coder/coder/releases/tag/v2.32.2) |\n| [**v2.31.12**](https://github.com/coder/coder/releases/tag/v2.31.12) |\n| [**v2.30.8**](https://github.com/coder/coder/releases/tag/v2.30.8) |\n| [**v2.29.13**](https://github.com/coder/coder/releases/tag/v2.29.13) |\n| [**v2.24.5**](https://github.com/coder/coder/releases/tag/v2.24.5) |\n\n## Workarounds\n\nIf unable to patch we recommend immediately reconfiguring any Azure templates to use token authentication rather than `azure-instance-identity` until the patch is released and you are fully upgraded.\n\n1. Modify the [`coder_agent.auth`](https://registry.terraform.io/providers/coder/coder/latest/docs/resources/agent#auth-1) value to be `token`.\n2. Add `CODER_AGENT_TOKEN=${coder_agent.main.token}` to the set of environment variables for the Coder Workspace Agent initialization script.\n\n## Recognition\n\nWe\u0027d like to thank [Ben Tran](https://github.com/bencalif) of [calif.io](http://calif.io) and Anthropic\u2019s Security Team (`ANT-2026-22445`) for independently disclosing this issue!",
  "id": "GHSA-6x44-w3xg-hqqf",
  "modified": "2026-05-19T20:04:13Z",
  "published": "2026-05-19T20:04:13Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/coder/coder/security/advisories/GHSA-6x44-w3xg-hqqf"
    },
    {
      "type": "WEB",
      "url": "https://github.com/coder/coder/pull/25286"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/coder/coder"
    },
    {
      "type": "WEB",
      "url": "https://github.com/coder/coder/releases/tag/v2.24.5"
    },
    {
      "type": "WEB",
      "url": "https://github.com/coder/coder/releases/tag/v2.29.13"
    },
    {
      "type": "WEB",
      "url": "https://github.com/coder/coder/releases/tag/v2.30.8"
    },
    {
      "type": "WEB",
      "url": "https://github.com/coder/coder/releases/tag/v2.31.12"
    },
    {
      "type": "WEB",
      "url": "https://github.com/coder/coder/releases/tag/v2.32.2"
    },
    {
      "type": "WEB",
      "url": "https://github.com/coder/coder/releases/tag/v2.33.3"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Coder: PKCS#7 signature bypass in Azure instance identity allows unauthenticated agent token theft"
}



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