GHSA-6w4m-2xhg-2658 is a critical-severity (CVSS 9.8) CWE-190 vulnerability in pysha3. 1 public exploit reference exists, so weaponization risk is real. A fix is available for pysha3 — see the affected versions and patch details below.
Buffer overflow in sponge queue functions
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.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA’s SSVC triage for GHSA-6w4m-2xhg-2658.
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-6w4m-2xhg-2658 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 377,333 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
pysha3💎sha3Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI, RubyGems packages — download data is not available via public APIs for these ecosystems.
Description
Impact
The Keccak sponge function interface accepts partial inputs to be absorbed and partial outputs to be squeezed. A buffer can overflow when partial data with some specific sizes are queued, where at least one of them has a length of 2^32 - 200 bytes or more.
Patches
Yes, see commit fdc6fef0.
Workarounds
The problem can be avoided by limiting the size of the partial input data (or partial output digest) below 2^32 - 200 bytes. Multiple calls to the queue system can be chained at a higher level to retain the original functionality. Alternatively, one can process the entire input (or produce the entire output) at once, avoiding the queuing functions altogether.
References
See issue #105 for more details.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | pysha3 | all versions | No fix |
| 💎RubyGems | sha3 | all versions | 1.0.5bundle update sha3 --conservative |
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 dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for pysha3, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
No patched version of pysha3 has shipped for GHSA-6w4m-2xhg-2658 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
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-6w4m-2xhg-2658 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-6w4m-2xhg-2658. 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.
Python as shipped with Red Hat Red Hat Enterprise Linux is not affected by this flaw as it uses the OpenSSL SHA-3 implementation. PHP as shipped with Red Hat Enterprise Linux is affected but not vulnerable by default as it depends of the memory_limit[1] configuration setting to have a value of -1, indicating there is…
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Enterprise Linux 8 | php:8.0-8070020230118114629.ef331662 | RHSA-2023:0848 |
| Red Hat Enterprise Linux 8 | php:7.4-8080020230118140634.cc342424 | RHSA-2023:2903 |
| Red Hat Enterprise Linux 9 | php-0:8.0.27-1.el9_1 | RHSA-2023:0965 |
| Red Hat Enterprise Linux 9 | php:8.1-9020020230120141750.9 | RHSA-2023:2417 |
Frequently Asked Questions
Is GHSA-6w4m-2xhg-2658 in your dependencies?
O3 Security finds GHSA-6w4m-2xhg-2658 across PyPI, RubyGems dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.