wisp has Allocation of Resources Without Limits or ThrottlingGHSA-8645-p2v4-73r2
Fix: gleam-wisp/wisp@7a97874GHSA-8645-p2v4-73r2 is a CWE-770 vulnerability in wisp. A fix is available for wisp — see the affected versions and patch details below.
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-8645-p2v4-73r2.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
Real-World Exposure
wispReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Hex packages — download data is not available via public APIs for these ecosystems.
Description
Summary
A multipart form parsing bug allows any unauthenticated user to bypass configured request size limits and trigger a denial of service by exhausting server memory or disk.
Details
The issue is in the multipart parsing logic, specifically in multipart_body and multipart_headers.
When parsing multipart data, the implementation distinguishes between:
- chunks where a boundary is found
- chunks where more data is required
In the normal case (boundary found), the parser correctly accounts for consumed bytes by calling decrement_quota.
However, in the MoreRequiredForBody branch, the parser appends incoming data to the output but recurses without decrementing the quota. This means that any chunk that does not contain the multipart boundary is effectively “free” from a quota perspective. Only the final chunk, the one containing the boundary, is counted.
The same pattern exists in multipart_headers, where MoreRequiredForHeaders also recurses without decrementing the quota.
As a result, an attacker can send arbitrarily large multipart bodies split across many chunks that avoid the boundary. The parser will accumulate the data (in memory for form fields, on disk for file uploads) without enforcing max_body_size or max_files_size.
Impact
This is a denial of service vulnerability caused by uncontrolled resource consumption.
Any application using require_form or require_multipart_form on user-controlled input is affected. An unauthenticated attacker can send large multipart requests that bypass configured limits and cause:
- memory exhaustion (for form fields accumulated in memory)
- disk exhaustion (for file uploads written to temporary storage)
In both cases, the application may become unavailable or be terminated by the operating system.
Workaround
Deploy a reverse proxy (such as nginx or HAProxy) in front of the application and enforce request body size limits there. This ensures large multipart requests are rejected before they reach the vulnerable parser.
Resources
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💧Hex | wisp | all versions | 2.2.2mix deps.update wisp |
Affected Products
wispgleam-wispDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for wisp, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update wisp to 2.2.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-8645-p2v4-73r2 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
Frequently Asked Questions
Is GHSA-8645-p2v4-73r2 in your dependencies?
Find it across Hex, including transitive dependencies.