GHSA-wpv5-97wm-hp9c is a high-severity (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in rack. A fix is available for rack — see the affected versions and patch details below.
Rack's multipart parser buffers unbounded per-part headers, enabling DoS (memory exhaustion)
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-wpv5-97wm-hp9c.
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-wpv5-97wm-hp9c 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
rack💎rack💎rackReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.
Description
Summary
Rack::Multipart::Parser can accumulate unbounded data when a multipart part’s header block never terminates with the required blank line (CRLFCRLF). The parser keeps appending incoming bytes to memory without a size cap, allowing a remote attacker to exhaust memory and cause a denial of service (DoS).
Details
While reading multipart headers, the parser waits for CRLFCRLF using:
@sbuf.scan_until(/(.*?\r\n)\r\n/m)
If the terminator never appears, it continues appending data (@sbuf.concat(content)) indefinitely. There is no limit on accumulated header bytes, so a single malformed part can consume memory proportional to the request body size.
Impact
Attackers can send incomplete multipart headers to trigger high memory use, leading to process termination (OOM) or severe slowdown. The effect scales with request size limits and concurrency. All applications handling multipart uploads may be affected.
Mitigation
- Upgrade to a patched Rack version that caps per-part header size (e.g., 64 KiB).
- Until then, restrict maximum request sizes at the proxy or web server layer (e.g., Nginx
client_max_body_size).
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | rack | all versions | 2.2.19bundle update rack --conservative |
| 💎RubyGems | rack | ≥ 3.1&&< 3.1.17 | 3.1.17bundle update rack --conservative |
| 💎RubyGems | rack | ≥ 3.2&&< 3.2.2 | 3.2.2bundle update rack --conservative |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rack, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update rack to 2.2.19 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-wpv5-97wm-hp9c 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-wpv5-97wm-hp9c can be triaged on real exposure rather than presence alone.
Tailored to GHSA-wpv5-97wm-hp9c. 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 availability risk to Red Hat systems is limited to the application which has integrated rack. The host operating system availability is not at risk.
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Enterprise Linux 10 | pcs-0:0.12.0-3.el10_0.3 | RHSA-2025:19513 |
| Red Hat Enterprise Linux 10 | pcs-0:0.12.1-1.el10_1.1 | RHSA-2025:21036 |
| Red Hat Enterprise Linux 8 | pcs-0:0.10.18-2.el8_10.7 | RHSA-2025:19719 |
| Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support | pcs-0:0.10.8-1.el8_4.8 | RHSA-2025:19948 |
| Red Hat Enterprise Linux 8.6 Telecommunications Update Service | pcs-0:0.10.12-6.el8_6.10 | RHSA-2025:19734 |
| Red Hat Enterprise Linux 8.8 Telecommunications Update Service | pcs-0:0.10.15-4.el8_8.9 | RHSA-2025:19647 |
| Red Hat Enterprise Linux 9 | pcs-0:0.11.9-2.el9_6.2 | RHSA-2025:19512 |
| Red Hat Enterprise Linux 9 | pcs-0:0.11.10-1.el9_7.1 | RHSA-2025:20962 |
Frequently Asked Questions
Is GHSA-wpv5-97wm-hp9c in your dependencies?
O3 Security finds GHSA-wpv5-97wm-hp9c across RubyGems dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.