CVE-2026-35201
MEDIUMCVE-2026-35201 is a medium-severity (CVSS 5.9) Out-of-bounds Read vulnerability in rdiscount. O3 Security confirms whether CVE-2026-35201 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Discount has an Out-of-bounds Read in rdiscount
Real-World Exposure
rdiscountReal-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
Discount is an implementation of John Gruber's Markdown markup language in C. From 1.3.1.1 to before 2.2.7.4, a signed length truncation bug causes an out-of-bounds read in the default Markdown parse path. Inputs larger than INT_MAX are truncated to a signed int before entering the native parser, allowing the parser to read past the end of the supplied buffer and crash the process. This vulnerability is fixed in 2.2.7.4.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | rdiscount | ≥ 1.3.1.1&&< 2.2.7.4 | 2.2.7.4 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rdiscount. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update rdiscount to 2.2.7.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-35201 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 pinpoints whether CVE-2026-35201 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-35201. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-35201 in your dependencies?
O3 detects CVE-2026-35201 across RubyGems dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.