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

> Attackers can bypass SNS signature verification by supplying a malicious SigningCertURL, allowing forged messages to be accepted as valid.

- **Severity:** High 8.7 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 28 May 2026
- **Updated:** 29 May 2026
- **Also known as:** EEF-CVE-2026-47074, GHSA-8jgf-23q5-x7xx

## What is CVE-2026-47074?

CVE-2026-47074 is a high-severity vulnerability in ex-aws ex_aws_sns, published on 28 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-295 (Improper Certificate Validation)

## Which versions are affected by CVE-2026-47074?

3 open source packages ship an affected version, including ex_aws_sns.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `ex_aws_sns` | Hex | From 2.0.1 | 2.3.5 |
| `ex_aws_sns` | Hex | From 2.0.1 | 2.3.5 |
| `ex_aws_sns` | Hex | From 2.0.1 | 2.3.5 |

## How do I fix CVE-2026-47074?

Upgrade ex_aws_sns to 2.3.5 or later.

## Is CVE-2026-47074 being exploited?

There is no known exploitation of CVE-2026-47074 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-47074 and fix it if it is affected.

What it is: CVE-2026-47074 is a high-severity vulnerability in ex-aws ex_aws_sns, published on 28 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-47074 in the wild and no public exploit code.

Affected packages and fixed versions:
- ex_aws_sns (Hex): affected from 2.0.1; fixed in 2.3.5
- ex_aws_sns (Hex): affected from 2.0.1; fixed in 2.3.5
- ex_aws_sns (Hex): affected from 2.0.1; fixed in 2.3.5

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-47074/ (Markdown: https://insights.sbomify.com/CVE-2026-47074/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-47074
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-47074
- OSV: https://osv.dev/vulnerability/CVE-2026-47074

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-47074/
Summaries are generated and may contain mistakes; the official description above is the record.