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MEDIUM severity

GHSA-r88r-gmrh-7j83 yaml.v2

MEDIUMFix: go-yaml/yaml#375

GHSA-r88r-gmrh-7j83 is a medium-severity (CVSS 5.5) vulnerability in gopkg.in/yaml.v2. 1 public exploit reference exists, so weaponization risk is real. A fix is available for gopkg.in/yaml.v2 — see the affected versions and patch details below.

YAML Go package vulnerable to denial of service

Also known asCVE-2021-4235GO-2021-0061
Published
Dec 28, 2022
Updated
Sep 10, 2026
Affected
2 pkgs
Patched
1 / 2
Exploits
1 known
Exploitation data as of Sep 19, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

  • CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.

Exploitation and automatability from CISA’s SSVC triage for GHSA-r88r-gmrh-7j83.

EPSS Exploitation Probability

via FIRST.org ↗
0.4%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs36th percentile — riskier than 36% of all scored CVEsHighest risk

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

How urgent is this, really

GHSA-r88r-gmrh-7j83 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.

Where this sits among everything scored

Of 377,166 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.

Real-World Exposure

2 pkgs affected
🐹gopkg.in/yaml.v2🐹github.com/go-yaml/yaml

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

Due to unbounded alias chasing, a maliciously crafted YAML file can cause the system to consume significant system resources. If parsing user input, this may be used as a denial of service vector.

Affected Packages

2 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐹Gogopkg.in/yaml.v2all versions2.2.3go get gopkg.in/yaml.v2@v2.2.3
🐹Gogithub.com/go-yaml/yamlall versionsNo fix
Exploits & PoCs
1

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

Detection & mitigation playbook

Open-source dependency
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for gopkg.in/yaml.v2, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update gopkg.in/yaml.v2 to 2.2.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-r88r-gmrh-7j83 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-r88r-gmrh-7j83 can be triaged on real exposure rather than presence alone.

Tailored to GHSA-r88r-gmrh-7j83. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate
ProductFixed inAdvisory
Red Hat OpenShift Container Platform 4.12openshift-clients-0:4.12.0-202301042257.p0.g854f807.assembly.stream.el8RHSA-2022:7398
Red Hat OpenShift Container Platform 4.12openshift4/ose-installer:v4.12.0-202301271115.p0.g7fea1c4.assembly.streamRHSA-2023:0569
Red Hat OpenShift Container Platform 4.12openshift4/metallb-rhel8-operator:v4.12.0-202301301729.p0.g917cd33.assembly.streamRHSA-2023:0570
Red Hat OpenShift Container Platform 4.12openshift4/ose-openshift-controller-manager-rhel8:v4.12.0-202306090942.p0.gb6528f9.assembly.streamRHSA-2023:3615
Red Hat OpenShift Container Platform 4.13openshift4/ose-installer:v4.13.0-202305091542.p0.g44db7b2.assembly.streamRHSA-2023:1326
RHODF-4.13-RHEL-9odf4/mcg-rhel9-operator:v4.13.0-41RHSA-2023:3742

Frequently Asked Questions

Due to unbounded alias chasing, a maliciously crafted YAML file can cause the system to consume significant system resources. If parsing user input, this may be used as a denial of service vector.
O3 Security · Impact-Aware SCA

Is GHSA-r88r-gmrh-7j83 in your dependencies?

O3 Security finds GHSA-r88r-gmrh-7j83 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.

GHSA-r88r-gmrh-7j83: yaml.v2 (Medium 5.5) | O3 Security