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Fencer Intel
medium 5.0

CVE-2011-5036 json

Rack Gem Subject to Denial of Service via Hash Collisions

published 2011-12-30 14 y ago modified 2026-06-16 4 mo ago also GHSA-v6j3-7jrw-hq2p , EUVD-2022-5298

cvss
5.0
version 2.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
3.9%
EPSS 3.9% chance of exploitation in 30 days, percentile 90%
public exploits
0
none known

Summary

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.

Patch / fix

  • rubygems rack 1.1.3, 1.2.5, 1.3.6
  • maven org.jruby:jruby-parent 1.6.5.1
  • ruby-rack Debian 14, Debian 13, Debian 12 1.4.0-1

debian advisories DEBIAN-CVE-2011-5036

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2011-5036 updated cvss 5.0

rubygem-rack: hash table collisions DoS (oCERT-2011-003)

  • Red Hat Subscription Asset Manager rubygem-rack
    affected: no fix planned “Will not fix”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

3.87% chance of exploitation in the next 30 days, higher than 90% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • gist.github.com https://gist.github.com/52bbc6b9cc19ce330829 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P

Affected packages

ecosystem package affected fixed in
rubygems rack
<1.1.3
>=1.2.0, <1.2.5
>=1.3.0, <1.3.6
1.1.3
1.2.5
1.3.6
maven org.jruby:jruby-parent
<1.6.5.1
1.6.5.1

Classification

Weakness

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.