# CVE-2026-31866: Allocation of Resources Without Limits or Throttling in flagd

> An attacker can cause denial of service in flagd by sending large payloads to evaluation endpoints, exhausting memory and crashing the process.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 11 Mar 2026
- **Updated:** 12 Mar 2026
- **Also known as:** GHSA-rmrf-g9r3-73pm, GO-2026-4674

## What is CVE-2026-31866?

CVE-2026-31866 is a high-severity denial of service vulnerability in open-feature flagd, published on 11 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

flagd is a feature flag daemon with a Unix philosophy. Prior to 0.14.2, flagd exposes OFREP (/ofrep/v1/evaluate/...) and gRPC (evaluation.v1, evaluation.v2) endpoints for feature flag evaluation. These endpoints are designed to be publicly accessible by client applications. The evaluation context included in request payloads is read into memory without any size restriction. An attacker can send a single HTTP request with an arbitrarily large body, causing flagd to allocate a corresponding amount of memory. This leads to immediate memory exhaustion and process termination (e.g., OOMKill in Kubernetes environments). flagd does not natively enforce authentication on its evaluation endpoints. While operators may deploy flagd behind an authenticating reverse proxy or similar infrastructure, the endpoints themselves impose no access control by default. This vulnerability is fixed in 0.14.2.

Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling)

## Which versions are affected by CVE-2026-31866?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/open-feature/flagd/flagd` | Go | All versions | 0.14.2 |
| `github.com/open-feature/flagd/flagd` | Go | All versions | 0.14.2 |
| `github.com/open-feature/flagd/flagd` | Go | All versions | 0.14.2 |

Products: Openfeature Flagd.

## How do I fix CVE-2026-31866?

Upgrade github.com/open-feature/flagd/flagd to 0.14.2 or later.

## Is CVE-2026-31866 being exploited?

There is no known exploitation of CVE-2026-31866 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-31866 and fix it if it is affected.

What it is: CVE-2026-31866 is a high-severity denial of service vulnerability in open-feature flagd, published on 11 Mar 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-2026-31866 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/open-feature/flagd/flagd (Go): affected all versions; fixed in 0.14.2
- github.com/open-feature/flagd/flagd (Go): affected all versions; fixed in 0.14.2
- github.com/open-feature/flagd/flagd (Go): affected all versions; fixed in 0.14.2

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-2026-31866/ (Markdown: https://insights.sbomify.com/CVE-2026-31866/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-31866
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-31866
- OSV: https://osv.dev/vulnerability/CVE-2026-31866

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-31866/
Summaries are generated and may contain mistakes; the official description above is the record.