GHSA-5c9c-6x87-f9vm is a high-severity (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in zstd. A fix is available for zstd — see the affected versions and patch details below.
zstd vulnerable to buffer overrun
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-5c9c-6x87-f9vm.
EPSS Exploitation Probability
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-5c9c-6x87-f9vm 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
zstd📦github.com/facebook/zstdReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI, SwiftURL packages — download data is not available via public APIs for these ecosystems.
Description
A vulnerability was found in zstd v1.4.10, where an attacker can supply an empty string as an argument to the command line tool to cause buffer overrun.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | zstd | all versions | 1.5.4.0pip install --upgrade 'zstd==1.5.4.0' |
| 📦SwiftURL | github.com/facebook/zstd | all versions | 1.5.4 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for zstd, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update zstd to 1.5.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-5c9c-6x87-f9vm is resolved across your whole dependency graph.
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.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-5c9c-6x87-f9vm can be triaged on real exposure rather than presence alone.
Tailored to GHSA-5c9c-6x87-f9vm. 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.
The vulnerability in the zstd command-line utility is rated as Moderate Severity because it involves an Incorrect Calculation of Buffer Size (CWE-400) within the mallocAndJoin2Dir function in programs/util.c. A remote attacker can exploit this flaw by providing an input, specifically an empty string, which causes a…
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat AMQ Streams 2.7.0 | see advisory | RHSA-2024:3527 |
| Red Hat Enterprise Linux 8 | mysql:8.0-8090020240126173013.a75119d5 | RHSA-2024:0894 |
| Red Hat Enterprise Linux 9 | mysql-0:8.0.36-1.el9_3 | RHSA-2024:1141 |
| Red Hat Software Collections for Red Hat Enterprise Linux 7 | rh-mysql80-mysql-0:8.0.36-1.el7 | RHSA-2024:2619 |
Frequently Asked Questions
Is GHSA-5c9c-6x87-f9vm in your dependencies?
O3 Security finds GHSA-5c9c-6x87-f9vm across PyPI, SwiftURL dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.