# CVE-2026-40481: monetr: Unauthenticated Stripe webhook reads attacker-sized request bodies before signature validation

> Unauthenticated attackers can cause denial of service in monetr by sending oversized payloads to the Stripe webhook endpoint before signature validation.

- **Severity:** High 8.2 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/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:** 17 Apr 2026
- **Updated:** 20 Apr 2026
- **Also known as:** GHSA-v7xq-3wx6-fqc2, GO-2026-5654

## What is CVE-2026-40481?

CVE-2026-40481 is a high-severity denial of service vulnerability in monetr, published on 17 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

monetr is a budgeting application for recurring expenses. In versions 1.12.3 and below, the public Stripe webhook endpoint buffers the entire request body into memory before validating the Stripe signature. A remote unauthenticated attacker can send oversized POST payloads to cause uncontrolled memory growth, leading to denial of service. The issue affects deployments with Stripe webhooks enabled and is mitigated if an upstream proxy enforces a request body size limit. This issue has been fixed in version 1.12.4.

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2026-40481?

3 open source packages ship an affected version, including github.com/monetr/monetr. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/monetr/monetr` | Go | All versions | 1.12.4 |
| `github.com/monetr/monetr` | Go | All versions | 1.12.4 |
| `github.com/monetr/monetr` | Go | All versions | 1.12.4 |

Products: Monetr Monetr.

## How do I fix CVE-2026-40481?

Upgrade github.com/monetr/monetr to 1.12.4 or later.

## Is CVE-2026-40481 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-40481 exists.

## Other vulnerabilities in monetr

- [CVE-2026-41644](https://insights.sbomify.com/CVE-2026-41644/): monetr is vulnerable to server-side request forgery in Lunch Flow link creation and refresh (high 8.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-40481 and fix it if it is affected.

What it is: CVE-2026-40481 is a high-severity denial of service vulnerability in monetr, published on 17 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-40481 exists.

Affected packages and fixed versions:
- github.com/monetr/monetr (Go): affected all versions; fixed in 1.12.4
- github.com/monetr/monetr (Go): affected all versions; fixed in 1.12.4
- github.com/monetr/monetr (Go): affected all versions; fixed in 1.12.4

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-2026-40481/ (Markdown: https://insights.sbomify.com/CVE-2026-40481/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-40481
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-40481
- OSV: https://osv.dev/vulnerability/CVE-2026-40481

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-40481/
Summaries are generated and may contain mistakes; the official description above is the record.