ex-aws ex_aws_sns up to 2.3.4 PublicKeyCache lib/ex_aws/sns.ex SigningCertURL certificate validation

Summaryinfo

A vulnerability was found in ex-aws ex_aws_sns up to 2.3.4. It has been classified as problematic. This impacts an unknown function in the library lib/ex_aws/sns.ex of the component PublicKeyCache Module. The manipulation of the argument SigningCertURL leads to certificate validation. This vulnerability is traded as CVE-2026-47074. It is possible to initiate the attack remotely. There is no exploit available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability was found in ex-aws ex_aws_sns up to 2.3.4. It has been rated as problematic. This issue affects an unknown code block in the library lib/ex_aws/sns.ex of the component PublicKeyCache Module. The manipulation of the argument SigningCertURL with an unknown input leads to a certificate validation vulnerability. Using CWE to declare the problem leads to CWE-295. The product does not validate, or incorrectly validates, a certificate. Impacted is integrity. The summary by CVE is:

Improper Certificate Validation vulnerability in ex-aws ex_aws_sns (ExAws.SNS, ExAws.SNS.PublicKeyCache modules) allows Signature Spoofing by Improper Validation. This 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. '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. This issue affects ex_aws_sns: from 2.0.1 before 2.3.5.

The weakness was shared by Peter Ullrich, Jonatan Männchen and Eef as GHSA-8jgf-23q5-x7xx. The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-47074 since 05/18/2026. The exploitation is known to be difficult. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1587.003 for this issue.

Upgrading to version 2.3.5 eliminates this vulnerability. Applying the patch 1853d280b152d10384a1e21a22cf22152a60be48 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Vendor

• ex-aws

Name

• ex_aws_sns

Version

• 2.3.0
• 2.3.1
• 2.3.2
• 2.3.3
• 2.3.4

License

• open-source

Website

• Product: https://github.com/ex-aws/ex_aws_sns/

CPE 2.3info

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CPE 2.2info

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