Vulnerability-Lookup

GHSA-WRQ8-FCV5-8HVP

Vulnerability from github – Published: 2026-07-06 20:58 – Updated: 2026-07-06 20:58

Summary

Coder: Route hijacking through lack of validation of agent-supplied AllowedIPs in tailnet coordinator

Details

Summary

The tailnet coordinator validates that an agent's Addresses derive from its authenticated UUID but applies no equivalent check to AllowedIPs. The coordinator forwards agent-supplied AllowedIPs verbatim to tunnel peers which install them into the WireGuard peer configuration.

Impact

A malicious workspace agent can advertise arbitrary AllowedIPs prefixes including another agent's tailnet address. Coder's ServerTailnet routes to agents by tailnet IP so an agent that claims a victim's prefix can intercept web terminal and workspace app traffic and serve spoofed content. Exploitation requires an authenticated user with a running workspace and a modified agent binary.

Patches

The fix validates each AllowedIPs prefix against the authenticating agent's UUID just like Addresses.

The fix was backported to all supported release lines:

Release line	Patched version
2.34	v2.34.2
2.33	v2.33.8
2.32	v2.32.7
2.29 (ESR)	v2.29.17

Workarounds

Operators who cannot upgrade immediately should monitor coordinator logs for agents advertising unexpected AllowedIPs prefixes.

Resources

Fix: #26144

Credits

Coder would like to thank Anthropic's Security Team (ANT-2026-22451) for independently disclosing this issue!

Severity

8.2 (High)


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

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{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/coder/coder/v2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.34.0"
            },
            {
              "fixed": "2.34.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/coder/coder/v2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.33.0"
            },
            {
              "fixed": "2.33.8"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/coder/coder/v2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.30.0"
            },
            {
              "fixed": "2.32.7"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/coder/coder/v2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.29.17"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-55428"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-285",
      "CWE-863"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-06T20:58:30Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "### Summary\n\nThe tailnet coordinator validates that an agent\u0027s `Addresses` derive from its authenticated UUID but applies no equivalent check to `AllowedIPs`. The coordinator forwards agent-supplied `AllowedIPs` verbatim to tunnel peers which install them into the WireGuard peer configuration.\n\n### Impact\n\nA malicious workspace agent can advertise arbitrary `AllowedIPs` prefixes including another agent\u0027s tailnet address. Coder\u0027s `ServerTailnet` routes to agents by tailnet IP so an agent that claims a victim\u0027s prefix can intercept web terminal and workspace app traffic and serve spoofed content. Exploitation requires an authenticated user with a running workspace and a modified agent binary.\n\n### Patches\n\nThe fix validates each `AllowedIPs` prefix against the authenticating agent\u0027s UUID just like `Addresses`.\n\nThe fix was backported to all supported release lines:\n\n| Release line | Patched version |\n|---|---|\n| 2.34 | [v2.34.2](https://github.com/coder/coder/releases/tag/v2.34.2) |\n| 2.33 | [v2.33.8](https://github.com/coder/coder/releases/tag/v2.33.8) |\n| 2.32 | [v2.32.7](https://github.com/coder/coder/releases/tag/v2.32.7) |\n| 2.29 (ESR) | [v2.29.17](https://github.com/coder/coder/releases/tag/v2.29.17) |\n\n### Workarounds\n\nOperators who cannot upgrade immediately should monitor coordinator logs for agents advertising unexpected `AllowedIPs` prefixes.\n\n### Resources\n\n- Fix: #26144\n\n### Credits\n\nCoder would like to thank Anthropic\u0027s Security Team (ANT-2026-22451) for independently disclosing this issue!",
  "id": "GHSA-wrq8-fcv5-8hvp",
  "modified": "2026-07-06T20:58:30Z",
  "published": "2026-07-06T20:58:30Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/coder/coder/security/advisories/GHSA-wrq8-fcv5-8hvp"
    },
    {
      "type": "WEB",
      "url": "https://github.com/coder/coder/pull/26144"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/coder/coder"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Coder: Route hijacking through lack of validation of agent-supplied AllowedIPs in tailnet coordinator"
}

CVE-2026-55428 (GCVE-0-2026-55428)

Vulnerability from cvelistv5 – Published: 2026-07-07 23:57 – Updated: 2026-07-08 13:11

Title

Coder: Route hijacking through lack of validation of agent-supplied AllowedIPs in tailnet coordinator

Summary

Coder allows organizations to provision remote development environments via Terraform. Prior to versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2, the tailnet coordinator validates that an agent's `Addresses` derive from its authenticated UUID but applies no equivalent check to `AllowedIPs`. The coordinator forwards agent-supplied `AllowedIPs` verbatim to tunnel peers which install them into the WireGuard peer configuration. The fix in versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2 validates each `AllowedIPs` prefix against the authenticating agent's UUID just like `Addresses`. As a workaround, monitor coordinator logs for agents advertising unexpected `AllowedIPs` prefixes.

Severity

8.2 (High)


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

SSVC

Exploitation: none Automatable: no Technical Impact: total

CISA Coordinator (v2.0.3)

CWE

CWE-285 - Improper Authorization
CWE-863 - Incorrect Authorization

Assigner

GitHub_M

References

6 references

URL	Tags
https://github.com/coder/coder/security/advisorie…	x_refsource_CONFIRM
https://github.com/coder/coder/pull/26144	x_refsource_MISC
https://github.com/coder/coder/releases/tag/v2.29.17	x_refsource_MISC
https://github.com/coder/coder/releases/tag/v2.32.7	x_refsource_MISC
https://github.com/coder/coder/releases/tag/v2.33.8	x_refsource_MISC
https://github.com/coder/coder/releases/tag/v2.34.2	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
coder	coder	Affected: >= 2.34.0, < 2.34.2 Affected: >= 2.33.0, < 2.33.8 Affected: >= 2.30.0, < 2.32.7 Affected: < 2.29.17

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-55428",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-07-08T13:10:59.507766Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-07-08T13:11:08.435Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "coder",
          "vendor": "coder",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 2.34.0, \u003c 2.34.2"
            },
            {
              "status": "affected",
              "version": "\u003e= 2.33.0, \u003c 2.33.8"
            },
            {
              "status": "affected",
              "version": "\u003e= 2.30.0, \u003c 2.32.7"
            },
            {
              "status": "affected",
              "version": "\u003c 2.29.17"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Coder allows organizations to provision remote development environments via Terraform. Prior to versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2, the tailnet coordinator validates that an agent\u0027s `Addresses` derive from its authenticated UUID but applies no equivalent check to `AllowedIPs`. The coordinator forwards agent-supplied `AllowedIPs` verbatim to tunnel peers which install them into the WireGuard peer configuration. The fix in versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2 validates each `AllowedIPs` prefix against the authenticating agent\u0027s UUID just like `Addresses`. As a workaround, monitor coordinator logs for agents advertising unexpected `AllowedIPs` prefixes."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 8.2,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "LOW",
            "scope": "CHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
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              "cweId": "CWE-285",
              "description": "CWE-285: Improper Authorization",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-863",
              "description": "CWE-863: Incorrect Authorization",
              "lang": "en",
              "type": "CWE"
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          ]
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      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-07T23:57:45.338Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/coder/coder/security/advisories/GHSA-wrq8-fcv5-8hvp",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/coder/coder/security/advisories/GHSA-wrq8-fcv5-8hvp"
        },
        {
          "name": "https://github.com/coder/coder/pull/26144",
          "tags": [
            "x_refsource_MISC"
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          "url": "https://github.com/coder/coder/pull/26144"
        },
        {
          "name": "https://github.com/coder/coder/releases/tag/v2.29.17",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/coder/coder/releases/tag/v2.29.17"
        },
        {
          "name": "https://github.com/coder/coder/releases/tag/v2.32.7",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/coder/coder/releases/tag/v2.32.7"
        },
        {
          "name": "https://github.com/coder/coder/releases/tag/v2.33.8",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/coder/coder/releases/tag/v2.33.8"
        },
        {
          "name": "https://github.com/coder/coder/releases/tag/v2.34.2",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/coder/coder/releases/tag/v2.34.2"
        }
      ],
      "source": {
        "advisory": "GHSA-wrq8-fcv5-8hvp",
        "discovery": "UNKNOWN"
      },
      "title": "Coder: Route hijacking through lack of validation of agent-supplied AllowedIPs in tailnet coordinator"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-55428",
    "datePublished": "2026-07-07T23:57:45.338Z",
    "dateReserved": "2026-06-16T21:59:57.016Z",
    "dateUpdated": "2026-07-08T13:11:08.435Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.

Action not permitted

GHSA-WRQ8-FCV5-8HVP

Summary

Impact

Patches

Workarounds

Resources

Credits

CVE-2026-55428 (GCVE-0-2026-55428)

Tags

Sightings

Nomenclature