Skip to content
Fencer Vulns
low 3.7

CVE-2026-54696 json

Ruby JSON: JSON generator heap buffer overflow when streaming to an IO

published 2026-06-30 4 mo ago modified 2026-10-25 14 d ago also EUVD-2026-40626 , GHSA-x2f5-4prf-w687

cvss
3.7
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 35%
public exploits
0
none known

Summary

Ruby JSON is a JSON implementation for Ruby. Versions 2.9.0 through 2.19.8 are vulnerable to heap buffer overflow when the JSON generator is provided with an oversized streamed object. When streaming to an IO JSON.dump(obj, io) and JSON::State#generate(obj, io) can write past the internal JSON generator buffer when a streamed object contains an attacker-controlled string near 16 KB. Exploitation would result in a reliable process crash/denial of service. This issue has been fixed in version 2.19.9.

Patch / fix

  • rubygems json 2.19.9
  • ruby-lang javascript_object_notation 2.19.9
  • ruby-lang json 2.19.9
  • rubygems json_gem 2.19.9
  • ruby-json Debian 14 2.19.9+dfsg-1

debian advisories DEBIAN-CVE-2026-54696

  • ruby3.4 hummingbird 1 3.4.10-31.5.hum1
  • ruby3.4-libs hummingbird 1 3.4.10-31.5.hum1
  • ruby3.4-bundled-gems hummingbird 1 3.4.10-31.5.hum1
  • ruby3.4-default-gems hummingbird 1 3.4.10-31.5.hum1
  • ruby4.0 hummingbird 1 4.0.6-37.1.hum1
  • ruby4.0-libs hummingbird 1 4.0.6-37.1.hum1
  • rubygem4.0-irb hummingbird 1 1.16.0-37.1.hum1
  • rubygem4.0-rbs hummingbird 1 3.10.0-37.1.hum1

red hat advisories RHSA-2026:48482RHSA-2026:47932

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-2026-54696 updated cvss 3.7

json: Ruby JSON: Denial of service via heap buffer overflow with oversized streamed objects

  • Red Hat 3scale API Management Platform 2 3scale-amp2/zync-rhel8, 3scale-amp2/system-rhel7, 3scale-amp2/backend-rhel8
    affected: no fix available, no fix planned “Out of support scope”
  • Red Hat AMQ Clients json 3.11.2-2.el8 Red Hat Enterprise Linux 8 pcs, ruby, pcs-snmp, ruby-irb, rubygems, ruby-libs, +29 more Red Hat Enterprise Linux 9 ruby, rubygems, ruby-libs, rubygem-irb, rubygem-rbs, rubygem-rss, +16 more Red Hat Enterprise Linux 10 ubi10/ruby-33, ubi10/ruby-40, ruby 3.3.10-13.el10_2, ruby4.0 4.0.3-35.el10_2 Red Hat OpenShift Dev Spaces devspaces/code-rhel9
    affected: no fix available “Fix deferred”
  • Red Hat Hardened Images ruby4.0 4.0.6-37.1.hum1, ruby3.4 3.4.10-31.5.hum1, ruby4.0-libs 4.0.6-37.1.hum1, ruby3.4-libs 3.4.10-31.5.hum1, rubygem4.0-rss 0.3.2-37.1.hum1, rubygem4.0-irb 1.16.0-37.1.hum1, +19 more
    fixed: vendor fix RHSA-2026:48482
  • Red Hat Enterprise Linux AI (RHEL AI) 3 json 3.11.2-2.el8 Red Hat Hardened Images ruby3.3 3.3.10-23.4.hum1, rubygem3.4-rbs 3.8.0-31.5.hum1, rubygem3.4-rss 0.3.1-31.5.hum1, rubygem3.4-irb 1.14.3-31.5.hum1, rubygem3.4-json 2.9.1-31.5.hum1, rubygem3.4-racc 1.8.1-31.5.hum1, +12 more Red Hat OpenShift AI (RHOAI) rhoai/odh-workbench-codeserver-datascience-cpu-py312-rhel9
    not affected: vulnerable code not present

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

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
4 mo ago

Exploit prediction

0.41% chance of exploitation in the next 30 days, higher than 35% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/ruby/json/security/advisories/GHSA-x2f5-4prf-w687 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 3.7 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
GitHub 3.1 3.7 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

Affected packages

ecosystem package affected fixed in
rubygems json
>=2.9.0, <2.19.9
2.19.9

Affected products

  • ruby json

Classification

Weakness
  • CWE-122 Heap-based Buffer Overflow
  • CWE-131 Incorrect Calculation of Buffer Size
  • CWE-787 Out-of-bounds Write

References

Sources

Fencer Vulns 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.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.