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CVE-2016-2338· NVD / CVE Program· CNA certcc

An exploitable heap overflow vulnerability exists in the Psych::Emitter start_document function of Ruby.

An exploitable heap overflow vulnerability exists in the Psych::Emitter start_document function of Ruby. In Psych::Emitter start_document function heap buffer "head" allocation is made based on tags array length. Specially constructed object passed as element of tags array can increase this array size after mentioned allocation and cause heap overflow.

CriticalCVSS 9.8 · v3.1—Proof of concept Fix available
Published
Sep 28, 2022
Updated
Jun 16, 2026
EPSS
4.7% · 91th percentile
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Report tools

JSON

Action score

40

Plan

Add it to your regular patch cycle.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
1 / 30 · 4.7%

Affected systems

VendorProduct
ruby-langruby
debiandebian linux

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • debian debian linux8.0
  • ruby-lang ruby2.2.2
  • ruby-lang ruby2.3.0

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:8ruby2.1before 2.1.5-2+deb8u92.1.5-2+deb8u9

Same product

ruby-lang: all records

Other highest-scoring records for the same primary product.

  • CVE-2017-17405Ruby before 2.4.3 allows Net::FTP command injection.
    57Plan
  • CVE-2008-3656Algorithmic complexity vulnerability in the WEBrick::HTTPUtils.split_header_value function in WEBrick::HTTP::DefaultFileHandler in WEBrick i
    52Plan
  • CVE-2021-28966In Ruby through 3.0 on Windows, a remote attacker can submit a crafted path when a Web application handles a parameter with TmpDir.
    47Plan
  • CVE-2017-14064Ruby through 2.2.7, 2.3.x through 2.3.4, and 2.4.x through 2.4.1 can expose arbitrary memory during a JSON.generate call.
    42Plan
  • CVE-2017-17790The lazy_initialize function in lib/resolv.rb in Ruby through 2.4.3 uses Kernel#open, which might allow Command Injection attacks, as demons
    41Plan
  • CVE-2016-2339An exploitable heap overflow vulnerability exists in the Fiddle::Function.new "initialize" function functionality of Ruby.
    41Plan

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
debian:ruby2.12.1.5-2+deb8u9 · Debian:8Package registry (OSV)

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Proof-of-concept repository on GitHub ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Proof-of-concept repository on GitHubstars:02022-12-19

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. Published
  2. First PoC+81 d
  3. TodaySep 30, 2026+1462 d
EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

The product’s vendor appears in a public program. Matched by name; verify the scope text in the program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-787 · Out-of-bounds Write

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Noroxi analysis

No Noroxi analysis for this record yet

We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.

We use this product, ask for help

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records