CVE-2026-47074: ex_aws_sns SigningCertURL not validated in verify_message/1

Severity: high (CVSS 8.7 v4.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-05-28 · updated 2026-10-26
Weakness: CWE-295

Description

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.

Affected products

ex-aws ex_aws_sns: from 2.0.1 before 2.3.5 — fixed in 2.3.5

How to fix

Upgrade to a fixed version: ex-aws ex_aws_sns 2.3.5. Check the vendor advisory for mitigations.

References

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