fugit parse and parse_nat stall on lengthy inputGHSA-2m96-52r3-2f3g
MEDIUMFix: floraison/fugit@ad2c1c9GHSA-2m96-52r3-2f3g is a medium-severity (CVSS 5.3) Uncontrolled Resource Consumption vulnerability in fugit. A fix is available for fugit — 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-2m96-52r3-2f3g.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
fugitReal-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
Impact
The fugit "natural" parser, that turns "every wednesday at 5pm" into "0 17 * * 3", accepted any length of input and went on attempting to parse it, not returning promptly, as expected. The parse call could hold the thread with no end in sight.
Fugit dependents that do not check (user) input length for plausability are impacted.
Patches
Problem was reported in #104 and the fix was released in fugit 1.11.1
Workarounds
By making sure that Fugit.parse(s), Fugit.do_parse(s), Fugit.parse_nat(s), Fugit.do_parse_nat(s), Fugit::Nat.parse(s), and Fugit::Nat.do_parse(s) are not fed strings too long. 1000 chars feels ok, while 10_000 chars makes it stall.
In fewer words, making sure those fugit methods are not fed unvetted input strings.
References
gh-104
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | fugit | all versions | 1.11.1bundle update fugit --conservative |
Affected Products
fugitfloraisonDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for fugit, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update fugit to 1.11.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-2m96-52r3-2f3g 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-2m96-52r3-2f3g in your dependencies?
Find it across RubyGems, including transitive dependencies.