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              "value": "\u003cp\u003eImproper Verification of Cryptographic Signature vulnerability in dashbit nimble_zta allows an unauthenticated remote attacker to authenticate as an arbitrary Cloudflare service token. Applications using the Cloudflare Zero Trust authentication strategy are affected.\u003c/p\u003e\n\u003cp\u003e\u003ccode\u003everify_token/2\u003c/code\u003e in \u003ccode\u003elib/nimble_zta/cloudflare.ex\u003c/code\u003e matches the result of \u003ccode\u003eJOSE.JWT.verify/2\u003c/code\u003e against \u003ccode\u003e{_, token, _s}\u003c/code\u003e, which discards the boolean verification result and returns the decoded token after a failed signature check. The attacker sends a forged JWT in the \u003ccode\u003ecf-access-jwt-assertion\u003c/code\u003e header, carrying the expected \u003ccode\u003eiss\u003c/code\u003e claim and the seven service token claims. \u003ccode\u003everify_iss/2\u003c/code\u003e reads the \u003ccode\u003eiss\u003c/code\u003e claim from the forged token, so it rejects nothing, and the service token path then returns those claims as the authenticated identity.\u003c/p\u003e\n\u003cp\u003eThis issue affects nimble_zta: from 0.1.2 before 0.1.3.\u003c/p\u003e"
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              "value": "Improper Verification of Cryptographic Signature vulnerability in dashbit nimble_zta allows an unauthenticated remote attacker to authenticate as an arbitrary Cloudflare service token. Applications using the Cloudflare Zero Trust authentication strategy are affected.\n\n`verify_token/2` in `lib/nimble_zta/cloudflare.ex` matches the result of `JOSE.JWT.verify/2` against `{_, token, _s}`, which discards the boolean verification result and returns the decoded token after a failed signature check. The attacker sends a forged JWT in the `cf-access-jwt-assertion` header, carrying the expected `iss` claim and the seven service token claims. `verify_iss/2` reads the `iss` claim from the forged token, so it rejects nothing, and the service token path then returns those claims as the authenticated identity.\n\nThis issue affects nimble_zta: from 0.1.2 before 0.1.3."
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          "value": "Improper Verification of Cryptographic Signature vulnerability in dashbit nimble_zta allows an unauthenticated remote attacker to authenticate as an arbitrary Cloudflare service token. Applications using the Cloudflare Zero Trust authentication strategy are affected.\n\nverify_token/2 in lib/nimble_zta/cloudflare.ex matches the result of JOSE.JWT.verify/2 against {_, token, _s}, which discards the boolean verification result and returns the decoded token after a failed signature check. The attacker sends a forged JWT in the cf-access-jwt-assertion header, carrying the expected iss claim and the seven service token claims. verify_iss/2 reads the iss claim from the forged token, so it rejects nothing, and the service token path then returns those claims as the authenticated identity.\n\nThis issue affects nimble_zta: from 0.1.2 before 0.1.3."
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                  "value": "\u003cp\u003eThe attacker authenticates as an arbitrary Cloudflare service token without holding the Cloudflare signing key. The application receives the \u003ccode\u003eclient_id\u003c/code\u003e and the claims of the forged token as the authenticated identity, so the attacker gets the access that the application grants to that service token.\u003c/p\u003e"
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                  "value": "The attacker authenticates as an arbitrary Cloudflare service token without holding the Cloudflare signing key. The application receives the `client_id` and the claims of the forged token as the authenticated identity, so the attacker gets the access that the application grants to that service token."
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              "value": "The attacker authenticates as an arbitrary Cloudflare service token without holding the Cloudflare signing key. The application receives the client_id and the claims of the forged token as the authenticated identity, so the attacker gets the access that the application grants to that service token."
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              "description": "CWE-347 Improper Verification of Cryptographic Signature",
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      "title": "Improper Verification of Cryptographic Signature in dashbit nimble_zta Cloudflare strategy",
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              "value": "\u003cp\u003eDisable the Cloudflare authentication strategy.\u003c/p\u003e\n\u003cp\u003eTo keep the user identity strategy available, reject the service token requests yourself. Examine each request before you call \u003ccode\u003eNimbleZTA.Cloudflare.authenticate/3\u003c/code\u003e, and reject it if its JWT carries the \u003ccode\u003ecommon_name\u003c/code\u003e claim and the \u003ccode\u003etype\u003c/code\u003e claim.\u003c/p\u003e"
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              "value": "Disable the Cloudflare authentication strategy.\n\nTo keep the user identity strategy available, reject the service token requests yourself. Examine each request before you call `NimbleZTA.Cloudflare.authenticate/3`, and reject it if its JWT carries the `common_name` claim and the `type` claim."
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          "value": "Disable the Cloudflare authentication strategy.\n\nTo keep the user identity strategy available, reject the service token requests yourself. Examine each request before you call NimbleZTA.Cloudflare.authenticate/3, and reject it if its JWT carries the common_name claim and the type claim."
        }
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              "value": "\u003col\u003e\n\u003cli\u003eBuild a JWT payload that carries the \u003ccode\u003eaud\u003c/code\u003e, \u003ccode\u003ecommon_name\u003c/code\u003e, \u003ccode\u003eexp\u003c/code\u003e, \u003ccode\u003eiat\u003c/code\u003e, \u003ccode\u003eiss\u003c/code\u003e, \u003ccode\u003esub\u003c/code\u003e and \u003ccode\u003etype\u003c/code\u003e claims. Use the \u003ccode\u003eiss\u003c/code\u003e the application expects, set \u003ccode\u003eexp\u003c/code\u003e to a future timestamp, and set \u003ccode\u003ecommon_name\u003c/code\u003e to the service token to impersonate.\u003c/li\u003e\n\u003cli\u003eAppend any signature segment. The segment must be present, because \u003ccode\u003eJOSE.JWT.verify/2\u003c/code\u003e needs three segments to parse the token. The signature does not need to verify against the Cloudflare keys.\u003c/li\u003e\n\u003cli\u003eSend a request to the application with the forged JWT in the \u003ccode\u003ecf-access-jwt-assertion\u003c/code\u003e header.\u003c/li\u003e\n\u003cli\u003e\u003ccode\u003eNimbleZTA.Cloudflare.authenticate/3\u003c/code\u003e returns the claims of the forged token as the authenticated identity, with the \u003ccode\u003estrategy\u003c/code\u003e field set to \u003ccode\u003eservice_token\u003c/code\u003e.\u003c/li\u003e\n\u003c/ol\u003e"
            },
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              "base64": false,
              "type": "text/markdown",
              "value": "1. Build a JWT payload that carries the `aud`, `common_name`, `exp`, `iat`, `iss`, `sub` and `type` claims. Use the `iss` the application expects, set `exp` to a future timestamp, and set `common_name` to the service token to impersonate.\n2. Append any signature segment. The segment must be present, because `JOSE.JWT.verify/2` needs three segments to parse the token. The signature does not need to verify against the Cloudflare keys.\n3. Send a request to the application with the forged JWT in the `cf-access-jwt-assertion` header.\n4. `NimbleZTA.Cloudflare.authenticate/3` returns the claims of the forged token as the authenticated identity, with the `strategy` field set to `service_token`."
            }
          ],
          "value": "* Build a JWT payload that carries the aud, common_name, exp, iat, iss, sub and type claims. Use the iss the application expects, set exp to a future timestamp, and set common_name to the service token to impersonate.\n* Append any signature segment. The segment must be present, because JOSE.JWT.verify/2 needs three segments to parse the token. The signature does not need to verify against the Cloudflare keys.\n* Send a request to the application with the forged JWT in the cf-access-jwt-assertion header.\n* NimbleZTA.Cloudflare.authenticate/3 returns the claims of the forged token as the authenticated identity, with the strategy field set to service_token."
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    "datePublished": "2026-09-24T13:20:52.974Z",
    "dateReserved": "2026-09-15T15:30:01.892Z",
    "dateUpdated": "2026-09-24T14:47:30.520Z",
    "state": "PUBLISHED"
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Examine each request before you call NimbleZTA.Cloudflare.authenticate/3, and reject it if its JWT carries the common_name claim and the type claim.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"\u003cp\u003eDisable the Cloudflare authentication strategy.\u003c/p\u003e\\n\u003cp\u003eTo keep the user identity strategy available, reject the service token requests yourself. Examine each request before you call \u003ccode\u003eNimbleZTA.Cloudflare.authenticate/3\u003c/code\u003e, and reject it if its JWT carries the \u003ccode\u003ecommon_name\u003c/code\u003e claim and the \u003ccode\u003etype\u003c/code\u003e claim.\u003c/p\u003e\", \"base64\": false}, {\"type\": \"text/markdown\", \"value\": \"Disable the Cloudflare authentication strategy.\\n\\nTo keep the user identity strategy available, reject the service token requests yourself. Examine each request before you call `NimbleZTA.Cloudflare.authenticate/3`, and reject it if its JWT carries the `common_name` claim and the `type` claim.\", \"base64\": false}]}], \"dateAssigned\": \"2026-09-24T09:09:36.000Z\", \"descriptions\": [{\"lang\": \"en\", \"value\": \"Improper Verification of Cryptographic Signature vulnerability in dashbit nimble_zta allows an unauthenticated remote attacker to authenticate as an arbitrary Cloudflare service token. Applications using the Cloudflare Zero Trust authentication strategy are affected.\\n\\nverify_token/2 in lib/nimble_zta/cloudflare.ex matches the result of JOSE.JWT.verify/2 against {_, token, _s}, which discards the boolean verification result and returns the decoded token after a failed signature check. The attacker sends a forged JWT in the cf-access-jwt-assertion header, carrying the expected iss claim and the seven service token claims. verify_iss/2 reads the iss claim from the forged token, so it rejects nothing, and the service token path then returns those claims as the authenticated identity.\\n\\nThis issue affects nimble_zta: from 0.1.2 before 0.1.3.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"\u003cp\u003eImproper Verification of Cryptographic Signature vulnerability in dashbit nimble_zta allows an unauthenticated remote attacker to authenticate as an arbitrary Cloudflare service token. Applications using the Cloudflare Zero Trust authentication strategy are affected.\u003c/p\u003e\\n\u003cp\u003e\u003ccode\u003everify_token/2\u003c/code\u003e in \u003ccode\u003elib/nimble_zta/cloudflare.ex\u003c/code\u003e matches the result of \u003ccode\u003eJOSE.JWT.verify/2\u003c/code\u003e against \u003ccode\u003e{_, token, _s}\u003c/code\u003e, which discards the boolean verification result and returns the decoded token after a failed signature check. The attacker sends a forged JWT in the \u003ccode\u003ecf-access-jwt-assertion\u003c/code\u003e header, carrying the expected \u003ccode\u003eiss\u003c/code\u003e claim and the seven service token claims. \u003ccode\u003everify_iss/2\u003c/code\u003e reads the \u003ccode\u003eiss\u003c/code\u003e claim from the forged token, so it rejects nothing, and the service token path then returns those claims as the authenticated identity.\u003c/p\u003e\\n\u003cp\u003eThis issue affects nimble_zta: from 0.1.2 before 0.1.3.\u003c/p\u003e\", \"base64\": false}, {\"type\": \"text/markdown\", \"value\": \"Improper Verification of Cryptographic Signature vulnerability in dashbit nimble_zta allows an unauthenticated remote attacker to authenticate as an arbitrary Cloudflare service token. Applications using the Cloudflare Zero Trust authentication strategy are affected.\\n\\n`verify_token/2` in `lib/nimble_zta/cloudflare.ex` matches the result of `JOSE.JWT.verify/2` against `{_, token, _s}`, which discards the boolean verification result and returns the decoded token after a failed signature check. The attacker sends a forged JWT in the `cf-access-jwt-assertion` header, carrying the expected `iss` claim and the seven service token claims. `verify_iss/2` reads the `iss` claim from the forged token, so it rejects nothing, and the service token path then returns those claims as the authenticated identity.\\n\\nThis issue affects nimble_zta: from 0.1.2 before 0.1.3.\", \"base64\": false}]}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-347\", \"description\": \"CWE-347 Improper Verification of Cryptographic Signature\"}]}], \"configurations\": [{\"lang\": \"en\", \"value\": \"The application must add NimbleZTA.Cloudflare to its supervision tree and authenticate requests through it.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"\u003cp\u003eThe application must add \u003ccode\u003eNimbleZTA.Cloudflare\u003c/code\u003e to its supervision tree and authenticate requests through it.\u003c/p\u003e\", \"base64\": false}, {\"type\": \"text/markdown\", \"value\": \"The application must add `NimbleZTA.Cloudflare` to its supervision tree and authenticate requests through it.\", \"base64\": false}]}], \"cpeApplicability\": [{\"nodes\": [{\"negate\": false, \"cpeMatch\": [{\"criteria\": \"cpe:2.3:a:dashbit:nimble_zta:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"0.1.3\", \"versionStartIncluding\": \"0.1.2\"}], \"operator\": \"OR\"}], \"operator\": \"AND\"}], \"providerMetadata\": {\"orgId\": \"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\", \"shortName\": \"EEF\", \"dateUpdated\": \"2026-09-24T13:20:52.974Z\"}, \"x_proofOfConcept\": [{\"lang\": \"en\", \"value\": \"* Build a JWT payload that carries the aud, common_name, exp, iat, iss, sub and type claims. Use the iss the application expects, set exp to a future timestamp, and set common_name to the service token to impersonate.\\n* Append any signature segment. The segment must be present, because JOSE.JWT.verify/2 needs three segments to parse the token. The signature does not need to verify against the Cloudflare keys.\\n* Send a request to the application with the forged JWT in the cf-access-jwt-assertion header.\\n* NimbleZTA.Cloudflare.authenticate/3 returns the claims of the forged token as the authenticated identity, with the strategy field set to service_token.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"\u003col\u003e\\n\u003cli\u003eBuild a JWT payload that carries the \u003ccode\u003eaud\u003c/code\u003e, \u003ccode\u003ecommon_name\u003c/code\u003e, \u003ccode\u003eexp\u003c/code\u003e, \u003ccode\u003eiat\u003c/code\u003e, \u003ccode\u003eiss\u003c/code\u003e, \u003ccode\u003esub\u003c/code\u003e and \u003ccode\u003etype\u003c/code\u003e claims. Use the \u003ccode\u003eiss\u003c/code\u003e the application expects, set \u003ccode\u003eexp\u003c/code\u003e to a future timestamp, and set \u003ccode\u003ecommon_name\u003c/code\u003e to the service token to impersonate.\u003c/li\u003e\\n\u003cli\u003eAppend any signature segment. The segment must be present, because \u003ccode\u003eJOSE.JWT.verify/2\u003c/code\u003e needs three segments to parse the token. The signature does not need to verify against the Cloudflare keys.\u003c/li\u003e\\n\u003cli\u003eSend a request to the application with the forged JWT in the \u003ccode\u003ecf-access-jwt-assertion\u003c/code\u003e header.\u003c/li\u003e\\n\u003cli\u003e\u003ccode\u003eNimbleZTA.Cloudflare.authenticate/3\u003c/code\u003e returns the claims of the forged token as the authenticated identity, with the \u003ccode\u003estrategy\u003c/code\u003e field set to \u003ccode\u003eservice_token\u003c/code\u003e.\u003c/li\u003e\\n\u003c/ol\u003e\", \"base64\": false}, {\"type\": \"text/markdown\", \"value\": \"1. Build a JWT payload that carries the `aud`, `common_name`, `exp`, `iat`, `iss`, `sub` and `type` claims. Use the `iss` the application expects, set `exp` to a future timestamp, and set `common_name` to the service token to impersonate.\\n2. Append any signature segment. The segment must be present, because `JOSE.JWT.verify/2` needs three segments to parse the token. The signature does not need to verify against the Cloudflare keys.\\n3. Send a request to the application with the forged JWT in the `cf-access-jwt-assertion` header.\\n4. `NimbleZTA.Cloudflare.authenticate/3` returns the claims of the forged token as the authenticated identity, with the `strategy` field set to `service_token`.\", \"base64\": false}]}]}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-91187\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-09-24T14:47:30.520Z\", \"dateReserved\": \"2026-09-15T15:30:01.892Z\", \"assignerOrgId\": \"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\", \"datePublished\": \"2026-09-24T13:20:52.974Z\", \"assignerShortName\": \"EEF\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}