Vulnerability-Lookup

CVE-2026-63443 (GCVE-0-2026-63443)

Vulnerability from cvelistv5 – Published: 2026-09-15 16:44 – Updated: 2026-09-15 17:31

Title

Coder: Workspace agent API insecure redirect handling allowed cross-agent file read and write

Summary

Coder allows organizations to provision remote development environments via Terraform. Prior to 2.29.19, 2.32.9, 2.33.10, and 2.34.4, agentConn.apiClient() follows redirects while its custom transport accepts the host from the redirected request URL when the port is the workspace agent HTTP API port 4. An authenticated user who controls a modified workspace agent and knows another online agent's UUID can derive the victim's tailnet address and redirect control-plane requests to that agent. HTTP 301, 302, and 303 redirects can redirect read requests, while HTTP 307 and 308 preserve replayable write and process-start requests. The redirected workspace agent file APIs can read or write files as the victim workspace user, and affected versions exposing the workspace agent process API can execute commands after a redirected file write, crossing workspace and tenant boundaries. This issue is fixed in versions 2.29.19, 2.32.9, 2.33.10, and 2.34.4.

Severity

8.3 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L

SSVC

Exploitation: none Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-15 17:31 UTC

CWE

CWE-863 - Incorrect Authorization
CWE-918 - Server-Side Request Forgery (SSRF)

Assigner

GitHub_M mitre root

References

15 references

URL	Tags
https://github.com/coder/coder/security/advisorie…	x_refsource_CONFIRM
https://github.com/coder/coder/pull/26600	x_refsource_MISC
https://github.com/coder/coder/pull/26611	x_refsource_MISC
https://github.com/coder/coder/pull/26612	x_refsource_MISC
https://github.com/coder/coder/pull/26613	x_refsource_MISC
https://github.com/coder/coder/pull/26622	x_refsource_MISC
https://github.com/coder/coder/commit/2312b67bc52…	x_refsource_MISC
https://github.com/coder/coder/commit/812549d671d…	x_refsource_MISC
https://github.com/coder/coder/commit/ec3ba84c000…	x_refsource_MISC
https://github.com/coder/coder/commit/eeb2624549d…	x_refsource_MISC
https://github.com/coder/coder/commit/f8bdec5add4…	x_refsource_MISC
https://github.com/coder/coder/releases/tag/v2.29.19	x_refsource_MISC
https://github.com/coder/coder/releases/tag/v2.32.9	x_refsource_MISC
https://github.com/coder/coder/releases/tag/v2.33.10	x_refsource_MISC
https://github.com/coder/coder/releases/tag/v2.34.4	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
coder	coder	Affected: >= 2.27.0, < 2.29.19 Affected: >= 2.30.0, < 2.32.9 Affected: >= 2.33.0, < 2.33.10 Affected: >= 2.34.0, < 2.34.4	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-63443

Vulnerability from fkie_nvd - Published: 2026-09-15 17:17 - Updated: 2026-09-15 18:17

Severity

8.3 (High) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/coder/coder/commit/2312b67bc52c4e314c18c4b4be5dcf5500c94ad7
	security-advisories@github.com	https://github.com/coder/coder/commit/812549d671d0f5a0b45adcee860d37b70aaddccd
	security-advisories@github.com	https://github.com/coder/coder/commit/ec3ba84c0002f47dd979c073cde1ab345acbaea5
	security-advisories@github.com	https://github.com/coder/coder/commit/eeb2624549ddb85538e493af3e678fdb185a809f
	security-advisories@github.com	https://github.com/coder/coder/commit/f8bdec5add4711650d5bfb6ff93d0cc9d7821c81
	security-advisories@github.com	https://github.com/coder/coder/pull/26600
	security-advisories@github.com	https://github.com/coder/coder/pull/26611
	security-advisories@github.com	https://github.com/coder/coder/pull/26612
	security-advisories@github.com	https://github.com/coder/coder/pull/26613
	security-advisories@github.com	https://github.com/coder/coder/pull/26622
	security-advisories@github.com	https://github.com/coder/coder/releases/tag/v2.29.19
	security-advisories@github.com	https://github.com/coder/coder/releases/tag/v2.32.9
	security-advisories@github.com	https://github.com/coder/coder/releases/tag/v2.33.10
	security-advisories@github.com	https://github.com/coder/coder/releases/tag/v2.34.4
	security-advisories@github.com	https://github.com/coder/coder/security/advisories/GHSA-qrwj-vh9x-gw5v

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "coder",
          "vendor": "coder",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 2.27.0, \u003c 2.29.19"
            },
            {
              "status": "affected",
              "version": "\u003e= 2.30.0, \u003c 2.32.9"
            },
            {
              "status": "affected",
              "version": "\u003e= 2.33.0, \u003c 2.33.10"
            },
            {
              "status": "affected",
              "version": "\u003e= 2.34.0, \u003c 2.34.4"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Coder allows organizations to provision remote development environments via Terraform. Prior to 2.29.19, 2.32.9, 2.33.10, and 2.34.4, agentConn.apiClient() follows redirects while its custom transport accepts the host from the redirected request URL when the port is the workspace agent HTTP API port 4. An authenticated user who controls a modified workspace agent and knows another online agent\u0027s UUID can derive the victim\u0027s tailnet address and redirect control-plane requests to that agent. HTTP 301, 302, and 303 redirects can redirect read requests, while HTTP 307 and 308 preserve replayable write and process-start requests. The redirected workspace agent file APIs can read or write files as the victim workspace user, and affected versions exposing the workspace agent process API can execute commands after a redirected file write, crossing workspace and tenant boundaries. This issue is fixed in versions 2.29.19, 2.32.9, 2.33.10, and 2.34.4."
    }
  ],
  "id": "CVE-2026-63443",
  "lastModified": "2026-09-15T18:17:29.010",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "LOW",
          "baseScore": 8.3,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 5.5,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-63443",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-09-15T17:31:25.407398Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-09-15T17:17:23.567",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/coder/coder/commit/2312b67bc52c4e314c18c4b4be5dcf5500c94ad7"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/coder/coder/commit/812549d671d0f5a0b45adcee860d37b70aaddccd"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/coder/coder/commit/ec3ba84c0002f47dd979c073cde1ab345acbaea5"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/coder/coder/commit/eeb2624549ddb85538e493af3e678fdb185a809f"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/coder/coder/commit/f8bdec5add4711650d5bfb6ff93d0cc9d7821c81"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/coder/coder/pull/26600"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/coder/coder/pull/26611"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/coder/coder/pull/26612"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/coder/coder/pull/26613"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/coder/coder/pull/26622"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/coder/coder/releases/tag/v2.29.19"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/coder/coder/releases/tag/v2.32.9"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/coder/coder/releases/tag/v2.33.10"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/coder/coder/releases/tag/v2.34.4"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/coder/coder/security/advisories/GHSA-qrwj-vh9x-gw5v"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Received",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-863"
        },
        {
          "lang": "en",
          "value": "CWE-918"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

GHSA-QRWJ-VH9X-GW5V

Vulnerability from github – Published: 2026-07-06 21:52 – Updated: 2026-07-06 21:52

Summary

Coder's workspace agent API insecure redirect handling allowed cross-agent file read and write

Details

Summary

agentConn.apiClient() used the default redirect behavior of http.Client while its custom transport dialed the host from the request URL as long as the port was the workspace agent HTTP API port (4). Agent tailnet IPs are deterministic from agent UUIDs, so a malicious workspace agent could return a redirect to another agent's tailnet IP and cause the control-plane client to send the follow-up workspace agent API request to the victim agent instead of the intended agent.

Redirects that preserve the method and body, such as HTTP 307 and 308, allow replay of write and process-start requests. HTTP 301, 302 and 303 redirects only convert POST requests to GET requests, so they are sufficient to demonstrate redirected reads but not write or command-execution primitives.

Impact

An authenticated user with a running workspace and control of a modified workspace agent can redirect workspace agent API requests made to their agent toward another online workspace agent reachable on the tailnet. If the attacker knows the victim agent UUID, they can derive the victim's tailnet IP and target the victim's file APIs to read or write files as the victim workspace user.

In affected versions that expose the workspace agent process API, the same primitive can be chained to command execution as the victim workspace user by writing a payload through the redirected file API and then redirecting a process-start request to execute it. This crosses workspace and tenant boundaries.

Patches

The fix disables automatic redirect following for workspace agent API clients and pins all workspace agent API dials to the intended agent's deterministic tailnet address. Requests whose URL host does not match the intended agent are rejected instead of being dialed.

The fix was backported to all supported release lines:

Release line	Patched version
2.34	v2.34.4
2.33	v2.33.10
2.32	v2.32.9
2.29 (ESR)	v2.29.19

Workarounds

None. Upgrading is required.

Resources

Fix: #26600

Severity

8.3 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/coder/coder/v2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.34.0"
            },
            {
              "fixed": "2.34.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/coder/coder/v2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.33.0"
            },
            {
              "fixed": "2.33.10"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/coder/coder/v2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.30.0"
            },
            {
              "fixed": "2.32.9"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/coder/coder/v2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.27.0"
            },
            {
              "fixed": "2.29.19"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [],
  "database_specific": {
    "cwe_ids": [
      "CWE-863",
      "CWE-918"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-06T21:52:31Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "### Summary\n\n`agentConn.apiClient()` used the default redirect behavior of `http.Client` while its custom transport dialed the host from the request URL as long as the port was the workspace agent HTTP API port (`4`). Agent tailnet IPs are deterministic from agent UUIDs, so a malicious workspace agent could return a redirect to another agent\u0027s tailnet IP and cause the control-plane client to send the follow-up workspace agent API request to the victim agent instead of the intended agent.\n\nRedirects that preserve the method and body, such as HTTP 307 and 308, allow replay of write and process-start requests. HTTP 301, 302 and 303 redirects only convert POST requests to GET requests, so they are sufficient to demonstrate redirected reads but not write or command-execution primitives.\n\n### Impact\n\nAn authenticated user with a running workspace and control of a modified workspace agent can redirect workspace agent API requests made to their agent toward another online workspace agent reachable on the tailnet. If the attacker knows the victim agent UUID, they can derive the victim\u0027s tailnet IP and target the victim\u0027s file APIs to read or write files as the victim workspace user.\n\nIn affected versions that expose the workspace agent process API, the same primitive can be chained to command execution as the victim workspace user by writing a payload through the redirected file API and then redirecting a process-start request to execute it. This crosses workspace and tenant boundaries.\n\n### Patches\n\nThe fix disables automatic redirect following for workspace agent API clients and pins all workspace agent API dials to the intended agent\u0027s deterministic tailnet address. Requests whose URL host does not match the intended agent are rejected instead of being dialed.\n\nThe fix was backported to all supported release lines:\n\n| Release line | Patched version |\n|---|---|\n| 2.34 | [v2.34.4](https://github.com/coder/coder/releases/tag/v2.34.4) |\n| 2.33 | [v2.33.10](https://github.com/coder/coder/releases/tag/v2.33.10) |\n| 2.32 | [v2.32.9](https://github.com/coder/coder/releases/tag/v2.32.9) |\n| 2.29 (ESR) | [v2.29.19](https://github.com/coder/coder/releases/tag/v2.29.19) |\n\n### Workarounds\n\nNone. Upgrading is required.\n\n### Resources\n- Fix: #26600",
  "id": "GHSA-qrwj-vh9x-gw5v",
  "modified": "2026-07-06T21:52:31Z",
  "published": "2026-07-06T21:52:31Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/coder/coder/security/advisories/GHSA-qrwj-vh9x-gw5v"
    },
    {
      "type": "WEB",
      "url": "https://github.com/coder/coder/pull/26600"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/coder/coder"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Coder\u0027s workspace agent API insecure redirect handling allowed cross-agent file read and write"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

Action not permitted

CVE-2026-63443 (GCVE-0-2026-63443)

FKIE_CVE-2026-63443

GHSA-QRWJ-VH9X-GW5V

Summary

Impact

Patches

Workarounds

Resources

Tags

Sightings

Nomenclature