{"id":"CVE-2026-47074","aliases":["EEF-CVE-2026-47074","EUVD-2026-32861","GHSA-8jgf-23q5-x7xx"],"status":"published","title":"ex_aws_sns SigningCertURL not validated in verify_message/1","description":"Improper Certificate Validation vulnerability in ex-aws ex_aws_sns (ExAws.SNS, ExAws.SNS.PublicKeyCache modules) allows Signature Spoofing by Improper Validation.\n\nThis vulnerability is associated with program files lib/ex_aws/sns.ex, lib/ex_aws/sns/public_key_cache.ex and program routines 'Elixir.ExAws.SNS':verify_message/1, 'Elixir.ExAws.SNS.PublicKeyCache':get/1.\n\n'Elixir.ExAws.SNS':verify_message/1 fetches the signing certificate from the SigningCertURL field of the incoming SNS message without validating that the URL uses HTTPS or that the host matches an AWS-owned SNS certificate domain. An unauthenticated attacker who can POST to an endpoint that calls verify_message/1 can supply an attacker-controlled SigningCertURL, sign a forged SNS message with their own key, and cause the function to return :ok, completely bypassing SNS signature verification.\n\nThis issue affects ex_aws_sns: from 2.0.1 before 2.3.5.","severity":{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00226,"percentile":0.13412,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-295"],"published":"2026-05-28T09:05:54Z","modified":"2026-10-28T02:30:26Z","fixes":[{"ecosystem":"Hex","package":"ex_aws_sns","fixed_in":["2.3.5"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"Hex","package":"ex_aws_sns","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.0.1"},{"fixed":"2.3.5"}]}]},{"source":"osv","ecosystem":"Hex","package":"ex_aws_sns","ranges":[{"type":"SEMVER","events":[{"introduced":"2.0.1"},{"fixed":"2.3.5"}]}],"versions":["2.0.1","2.1.0","2.2.0","2.3.0","2.3.1","2.3.2","2.3.3","2.3.4"]},{"source":"osv","ecosystem":"Hex","package":"ex_aws_sns","ranges":[{"type":"SEMVER","events":[{"introduced":"2.0.1"},{"fixed":"2.3.5"}]}],"versions":["2.0.1","2.1.0","2.2.0","2.3.0","2.3.1","2.3.2","2.3.3","2.3.4"]}],"products":[{"vendor":"ex-aws","product":"ex_aws_sns"}],"references":[{"url":"https://github.com/ex-aws/ex_aws_sns/security/advisories/GHSA-8jgf-23q5-x7xx","tags":["vendor-advisory","related","advisory","web"]},{"url":"https://cna.erlef.org/cves/CVE-2026-47074.html","tags":["related","web"]},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-47074","tags":["related","web"]},{"url":"https://github.com/ex-aws/ex_aws_sns/commit/1853d280b152d10384a1e21a22cf22152a60be48","tags":["patch","fix","web"]},{"url":"https://github.com/benoitc/hackney/security/advisories/GHSA-jq4m-q6p2-8gwc","tags":["web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-47074","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-8jgf-23q5-x7xx"},{"url":"https://github.com","tags":["web"]},{"url":"https://hex.pm","tags":["web"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/47xxx/CVE-2026-47074.json","tags":["advisory"]},{"url":"https://github.com/ex-aws/ex_aws_sns","tags":["package"]},{"url":"https://hex.pm/packages/ex_aws_sns","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-47074","title":"ex_aws_sns SigningCertURL not validated in verify_message/1","description":"Improper Certificate Validation vulnerability in ex-aws ex_aws_sns (ExAws.SNS, ExAws.SNS.PublicKeyCache modules) allows Signature Spoofing by Improper Validation.\n\nThis vulnerability is associated with program files lib/ex_aws/sns.ex, lib/ex_aws/sns/public_key_cache.ex and program routines 'Elixir.ExAws.SNS':verify_message/1, 'Elixir.ExAws.SNS.PublicKeyCache':get/1.\n\n'Elixir.ExAws.SNS':verify_message/1 fetches the signing certificate from the SigningCertURL field of the incoming SNS message without validating that the URL uses HTTPS or that the host matches an AWS-owned SNS certificate domain. An unauthenticated attacker who can POST to an endpoint that calls verify_message/1 can supply an attacker-controlled SigningCertURL, sign a forged SNS message with their own key, and cause the function to return :ok, completely bypassing SNS signature verification.\n\nThis issue affects ex_aws_sns: from 2.0.1 before 2.3.5.","status":"published","published":"2026-05-28T09:05:54.815Z","modified":"2026-05-29T04:40:43.232Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N","level":"high","assessor":"cna"}],"cwes":["CWE-295"],"updated_at":"2026-11-02T13:36:40.478484Z"}],"euvd":[{"id":"EUVD-2026-32861","description":"Improper Certificate Validation vulnerability in ex-aws ex_aws_sns (ExAws.SNS, ExAws.SNS.PublicKeyCache modules) allows Signature Spoofing by Improper Validation.\n\nThis vulnerability is associated with program files lib/ex_aws/sns.ex, lib/ex_aws/sns/public_key_cache.ex and program routines 'Elixir.ExAws.SNS':verify_message/1, 'Elixir.ExAws.SNS.PublicKeyCache':get/1.\n\n'Elixir.ExAws.SNS':verify_message/1 fetches the signing certificate from the SigningCertURL field of the incoming SNS message without validating that the URL uses HTTPS or that the host matches an AWS-owned SNS certificate domain. An unauthenticated attacker who can POST to an endpoint that calls verify_message/1 can supply an attacker-controlled SigningCertURL, sign a forged SNS message with their own key, and cause the function to return :ok, completely bypassing SNS signature verification.\n\nThis issue affects ex_aws_sns: from 2.0.1 before 2.3.5.","status":"published","published":"2026-05-28T09:05:54Z","modified":"2026-05-29T04:40:43Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N","level":"high"}],"updated_at":"2026-11-02T18:21:01.680356Z"}],"ghsa":[{"id":"GHSA-8jgf-23q5-x7xx","title":"ex_aws_sns: Trusted-attacker `SigningCertURL` permits complete SNS signature bypass","description":"### Summary\n\n`ExAws.SNS.verify_message/1` fetches the signing certificate from the `SigningCertURL` field of the incoming SNS message without validating that the URL uses HTTPS or that its host is an AWS-owned SNS certificate domain. An unauthenticated attacker who can POST to any endpoint that calls `verify_message/1` can supply an attacker-controlled `SigningCertURL`, sign a forged SNS message with their own RSA key, and cause the function to return `:ok`, completely bypassing SNS signature verification.\n\n### Details\n\nIn `lib/ex_aws/sns.ex` (lines 475–483), `verify_message/1` performs three checks: `validate_message_params/1` (confirms required fields are present), `validate_signature_version/1` (confirms `SignatureVersion == \"1\"`), then signature verification. The signature step calls `ExAws.SNS.PublicKeyCache.get(message[\"SigningCertURL\"])` and passes the result to `:public_key.verify/4`.\n\nNeither `validate_message_params/1` nor any other step checks that `SigningCertURL` is an HTTPS URL or that the hostname matches the expected pattern (e.g. `sns.\u003cregion\u003e.amazonaws.com`). `PublicKeyCache.get/1` in `lib/ex_aws/sns/public_key_cache.ex` fetches whatever URL is provided and caches the certificate. The RSA signature then verifies against the attacker's own public key, and `verify_message/1` returns `:ok`.\n\n### PoC\n\n1. Generate an RSA keypair and host the DER/PEM public certificate at any URL reachable from the target server (e.g. `http://attacker.example/cert.pem`).\n2. Build a forged `Notification` payload with an arbitrary `TopicArn` and `Message`, compute the canonical string-to-sign per the SNS spec, and sign it with the attacker private key.\n3. Set `SigningCertURL` to the attacker URL and `Signature` to the base64-encoded signature.\n4. POST the forged payload to any SNS webhook endpoint that calls `ExAws.SNS.verify_message/1`.\n5. The function returns `:ok`; the application treats the message as authentic.\n\n### Configurations\n\nThe application must expose an HTTP endpoint that calls `ExAws.SNS.verify_message/1` on incoming request bodies (the standard SNS webhook pattern).\n\n### Impact\n\nComplete SNS signature authentication bypass. Affects `ex_aws_sns` from 2.0.1 through 2.3.4. Consequences include spoofing arbitrary `Notification` payloads, auto-confirming attacker-controlled `SubscribeURL` values to hijack topic delivery, and spoofing `UnsubscribeConfirmation` to disrupt legitimate subscriptions. No authentication or special configuration on the attacker side is required. CVSS v4.0: **8.7 (HIGH)**.\n\n## Resources\n\n* Introduction commit: https://github.com/ex-aws/ex_aws_sns/commit/a7ec21880943f4dac1d59bda557db0ffcd2b61fa\n* Patch commit: https://github.com/ex-aws/ex_aws_sns/commit/1853d280b152d10384a1e21a22cf22152a60be48","status":"published","published":"2026-06-26T22:50:27Z","modified":"2026-06-30T17:16:17Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-295"],"updated_at":"2026-11-02T14:40:35.701766Z"}],"nvd":[{"id":"CVE-2026-47074","description":"Improper Certificate Validation vulnerability in ex-aws ex_aws_sns (ExAws.SNS, ExAws.SNS.PublicKeyCache modules) allows Signature Spoofing by Improper Validation.\n\nThis vulnerability is associated with program files lib/ex_aws/sns.ex, lib/ex_aws/sns/public_key_cache.ex and program routines 'Elixir.ExAws.SNS':verify_message/1, 'Elixir.ExAws.SNS.PublicKeyCache':get/1.\n\n'Elixir.ExAws.SNS':verify_message/1 fetches the signing certificate from the SigningCertURL field of the incoming SNS message without validating that the URL uses HTTPS or that the host matches an AWS-owned SNS certificate domain. An unauthenticated attacker who can POST to an endpoint that calls verify_message/1 can supply an attacker-controlled SigningCertURL, sign a forged SNS message with their own key, and cause the function to return :ok, completely bypassing SNS signature verification.\n\nThis issue affects ex_aws_sns: from 2.0.1 before 2.3.5.","status":"published","published":"2026-05-28T10:16:39.8Z","modified":"2026-10-26T11:10:00.157Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high","assessor":"secondary"}],"cwes":["CWE-295"],"updated_at":"2026-11-02T14:12:21.244426Z"}],"osv":[{"id":"CVE-2026-47074","title":"ex_aws_sns SigningCertURL not validated in verify_message/1","description":"Improper Certificate Validation vulnerability in ex-aws ex_aws_sns (ExAws.SNS, ExAws.SNS.PublicKeyCache modules) allows Signature Spoofing by Improper Validation.\n\nThis vulnerability is associated with program files lib/ex_aws/sns.ex, lib/ex_aws/sns/public_key_cache.ex and program routines 'Elixir.ExAws.SNS':verify_message/1, 'Elixir.ExAws.SNS.PublicKeyCache':get/1.\n\n'Elixir.ExAws.SNS':verify_message/1 fetches the signing certificate from the SigningCertURL field of the incoming SNS message without validating that the URL uses HTTPS or that the host matches an AWS-owned SNS certificate domain. An unauthenticated attacker who can POST to an endpoint that calls verify_message/1 can supply an attacker-controlled SigningCertURL, sign a forged SNS message with their own key, and cause the function to return :ok, completely bypassing SNS signature verification.\n\nThis issue affects ex_aws_sns: from 2.0.1 before 2.3.5.","status":"published","published":"2026-05-28T09:05:54.815Z","modified":"2026-10-28T02:30:26.751022787Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-295"],"updated_at":"2026-11-02T15:45:06.231145Z"},{"id":"EEF-CVE-2026-47074","title":"ex_aws_sns SigningCertURL not validated in verify_message/1","description":"## Summary\n\nImproper Certificate Validation vulnerability in ex-aws ex\\_aws\\_sns (ExAws.SNS, ExAws.SNS.PublicKeyCache modules) allows Signature Spoofing by Improper Validation.\n\nThis vulnerability is associated with program files lib/ex\\_aws/sns.ex, lib/ex\\_aws/sns/public\\_key\\_cache.ex and program routines 'Elixir.ExAws.SNS':verify\\_message/1, 'Elixir.ExAws.SNS.PublicKeyCache':get/1.\n\n'Elixir.ExAws.SNS':verify\\_message/1 fetches the signing certificate from the SigningCertURL field of the incoming SNS message without validating that the URL uses HTTPS or that the host matches an AWS-owned SNS certificate domain. An unauthenticated attacker who can POST to an endpoint that calls verify\\_message/1 can supply an attacker-controlled SigningCertURL, sign a forged SNS message with their own key, and cause the function to return :ok, completely bypassing SNS signature verification.\n\nThis issue affects ex\\_aws\\_sns: from 2.0.1 before 2.3.5.\n\n## Configurations\n\nThe application must expose an HTTP endpoint that calls 'Elixir.ExAws.SNS':verify\\_message/1 on incoming request bodies.","status":"published","published":"2026-05-28T09:05:54.815Z","modified":"2026-09-08T03:45:07.615311335Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-295"],"updated_at":"2026-11-02T15:46:33.047032Z"},{"id":"GHSA-8jgf-23q5-x7xx","title":"ex_aws_sns: Trusted-attacker `SigningCertURL` permits complete SNS signature bypass","description":"### Summary\n\n`ExAws.SNS.verify_message/1` fetches the signing certificate from the `SigningCertURL` field of the incoming SNS message without validating that the URL uses HTTPS or that its host is an AWS-owned SNS certificate domain. An unauthenticated attacker who can POST to any endpoint that calls `verify_message/1` can supply an attacker-controlled `SigningCertURL`, sign a forged SNS message with their own RSA key, and cause the function to return `:ok`, completely bypassing SNS signature verification.\n\n### Details\n\nIn `lib/ex_aws/sns.ex` (lines 475–483), `verify_message/1` performs three checks: `validate_message_params/1` (confirms required fields are present), `validate_signature_version/1` (confirms `SignatureVersion == \"1\"`), then signature verification. The signature step calls `ExAws.SNS.PublicKeyCache.get(message[\"SigningCertURL\"])` and passes the result to `:public_key.verify/4`.\n\nNeither `validate_message_params/1` nor any other step checks that `SigningCertURL` is an HTTPS URL or that the hostname matches the expected pattern (e.g. `sns.\u003cregion\u003e.amazonaws.com`). `PublicKeyCache.get/1` in `lib/ex_aws/sns/public_key_cache.ex` fetches whatever URL is provided and caches the certificate. The RSA signature then verifies against the attacker's own public key, and `verify_message/1` returns `:ok`.\n\n### PoC\n\n1. Generate an RSA keypair and host the DER/PEM public certificate at any URL reachable from the target server (e.g. `http://attacker.example/cert.pem`).\n2. Build a forged `Notification` payload with an arbitrary `TopicArn` and `Message`, compute the canonical string-to-sign per the SNS spec, and sign it with the attacker private key.\n3. Set `SigningCertURL` to the attacker URL and `Signature` to the base64-encoded signature.\n4. POST the forged payload to any SNS webhook endpoint that calls `ExAws.SNS.verify_message/1`.\n5. The function returns `:ok`; the application treats the message as authentic.\n\n### Configurations\n\nThe application must expose an HTTP endpoint that calls `ExAws.SNS.verify_message/1` on incoming request bodies (the standard SNS webhook pattern).\n\n### Impact\n\nComplete SNS signature authentication bypass. Affects `ex_aws_sns` from 2.0.1 through 2.3.4. Consequences include spoofing arbitrary `Notification` payloads, auto-confirming attacker-controlled `SubscribeURL` values to hijack topic delivery, and spoofing `UnsubscribeConfirmation` to disrupt legitimate subscriptions. No authentication or special configuration on the attacker side is required. CVSS v4.0: **8.7 (HIGH)**.\n\n## Resources\n\n* Introduction commit: https://github.com/ex-aws/ex_aws_sns/commit/a7ec21880943f4dac1d59bda557db0ffcd2b61fa\n* Patch commit: https://github.com/ex-aws/ex_aws_sns/commit/1853d280b152d10384a1e21a22cf22152a60be48","status":"published","published":"2026-06-26T22:50:27Z","modified":"2026-06-30T17:41:03.698517863Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-295"],"updated_at":"2026-11-02T15:46:42.437513Z"}]}}