How severe is CVE-2011-5036?

No CVSS score has been assigned to CVE-2011-5036 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2011-5036?

CVE-2011-5036 affects the following packages: org.jruby:jruby-parent (Maven), rack (RubyGems), rack (RubyGems), rack (RubyGems). Ecosystems affected: Maven, RubyGems.

How do I fix CVE-2011-5036?

Update org.jruby:jruby-parent to 1.6.5.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2011-5036 is resolved across your whole dependency graph.

How do I detect CVE-2011-5036 in my Maven, RubyGems dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.jruby:jruby-parent, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2011-5036 if there is no patch (or I can't update yet)?

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.

Is CVE-2011-5036 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2011-5036, including 1 in-the-wild exploitation observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2011-5036?

CVE-2011-5036 has an EPSS (Exploit Prediction Scoring System) score of 3.9%, placing it in the 90th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2011-5036?

CVE-2011-5036 is classified as CWE-310 (CWE-310). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2011-5036 published, and has it been updated?

CVE-2011-5036 was published on December 30, 2011 and was last updated on April 10, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕ Maven💎 RubyGems

Not in CISA KEV

CVE-2011-5036 — jruby-parent

CVE-2011-5036 is a CWE-310 vulnerability in org.jruby:jruby-parent. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for org.jruby:jruby-parent — see the affected versions and patch details below.

Rack Gem Subject to Denial of Service via Hash Collisions

Also known asGHSA-v6j3-7jrw-hq2p

Published

Dec 30, 2011

Updated

Apr 10, 2026

Affected

4 pkgs

Patched

4 / 4

Exploits

1 known

Exploitation data as of Oct 29, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

3.9%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs90th percentile — riskier than 90% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

4 pkgs affected

☕org.jruby:jruby-parent💎rack💎rack💎rack

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven, RubyGems packages — download data is not available via public APIs for these ecosystems.

Description

Rack before 1.1.3, 1.2.x before 1.2.5, and 1.3.x before 1.3.6 computes hash values for form parameters without restricting the ability to trigger hash collisions predictably, which allows remote attackers to cause a denial of service (CPU consumption) by sending many crafted parameters.

Affected Packages

4 total 4 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`org.jruby:jruby-parent`	all versions	1.6.5.1`org.jruby:jruby-parent:1.6.5.1`
💎RubyGems	`rack`	all versions	1.1.3`bundle update rack --conservative`
💎RubyGems	`rack`	≥ 1.2.0&&< 1.2.5	1.2.5`bundle update rack --conservative`
💎RubyGems	`rack`	≥ 1.3.0&&< 1.3.6	1.3.6`bundle update rack --conservative`

Affected Products

1 product · 12 configurations

Application

rackrack_project

≤ 1.1.0

11 versions

1.2.01.2.11.2.21.2.31.2.41.3.01.3.11.3.21.3.31.3.41.3.5

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

Rack before 1.1.3, 1.2.x before 1.2.5, and 1.3.x before 1.3.6 computes h…

gist.github.comNVDOct 2013

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.jruby:jruby-parent, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.jruby:jruby-parent to 1.6.5.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2011-5036 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.