GHSA-4c5f-9mj4-m247 flagd: Multiple Go Runtime CVEs Impact Security and Availability
Attackers can cause denial of service or data corruption in flagd by exploiting multiple Go standard library vulnerabilities via crafted inputs.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is GHSA-4c5f-9mj4-m247?
GHSA-4c5f-9mj4-m247 is a denial of service vulnerability in github.com/open-feature/flagd/core, published on 5 Jan 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Summary
In 2025, several vulnerabilities in the Go Standard Library were disclosed, impacting Go-based applications like flagd (the evaluation engine for OpenFeature). These CVEs primarily focus on Denial of Service (DoS) through resource exhaustion and Race Conditions in database handling.
| CVE ID | Impacted Package | Severity | Description & Impact on flagd |
|---|---|---|---|
| CVE-2025-47907 | database/sql | 7.0 (High) | Race Condition: Canceling a query during a Scan call can return data from the wrong query. Critical if flagd uses SQL-based sync providers (e.g., Postgres), potentially leading to incorrect flag configurations. |
| CVE-2025-61725 | net/mail | 7.5 (High) | DoS: Inefficient complexity in ParseAddress. Attackers can provide crafted email strings with large domain literals to exhaust CPU if flagd parses email-formatted metadata. |
| CVE-2025-61723 | encoding/pem | 7.5 (High) | DoS: Quadratic complexity when parsing invalid PEM inputs. Relevant if flagd loads TLS certificates or keys via PEM files from untrusted sources. |
| CVE-2025-61729 | crypto/x509 | 7.5 (High) | Resource Exhaustion: HostnameError.Error() lacks string concatenation limits. A malicious TLS certificate with thousands of hostnames could crash flagd during connection handshakes. |
| CVE-2025-58188 | net/http | Medium | Request Smuggling: Improper header handling in HTTP/1.1. Could allow attackers to bypass security filters positioned in front of flagd sync or evaluation APIs. |
| CVE-2025-58187 | archive/zip | Medium | DoS: Improper validation of malformed ZIP archives. Impacts flagd if configured to fetch and unpack zipped configuration bundles from remote providers. |
Which versions are affected by GHSA-4c5f-9mj4-m247?
9 open source packages ship an affected version, including github.com/open-feature/flagd/core, github.com/open-feature/flagd/flagd and github.com/open-feature/flagd/flagd-proxy.
| Package | Affected | Fixed in |
|---|---|---|
github.com/open-feature/flagd/core Go | All versions | 0.13.1 |
github.com/open-feature/flagd/core Go | All versions | 0.13.1 |
github.com/open-feature/flagd/core Go | All versions | 0.13.1 |
github.com/open-feature/flagd/flagd Go | All versions | 0.13.1 |
github.com/open-feature/flagd/flagd Go | All versions | 0.13.1 |
github.com/open-feature/flagd/flagd Go | All versions | 0.13.1 |
3 more packages
github.com/open-feature/flagd/flagd-proxy Go | All versions | 0.8.2 |
github.com/open-feature/flagd/flagd-proxy Go | All versions | 0.8.2 |
github.com/open-feature/flagd/flagd-proxy Go | All versions | 0.8.2 |
How do I fix GHSA-4c5f-9mj4-m247?
Upgrade github.com/open-feature/flagd/core to 0.13.1 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is GHSA-4c5f-9mj4-m247 being exploited?
There is no known exploitation of GHSA-4c5f-9mj4-m247 in the wild and no public exploit code.
Sources
Also known as GO-2026-4279.