The parser_yyerror function in the UTF-8 parser in Ruby 2.4.1 allows attackers to cause a denial of service (invalid write or read) or possi
The parser_yyerror function in the UTF-8 parser in Ruby 2.4.1 allows attackers to cause a denial of service (invalid write or read) or possibly have unspecified other impact via a crafted Ruby script, related to the parser_tokadd_utf8 function in parse.y. NOTE: this might have security relevance as a bypass of a $SAFE protection mechanism.
- Published
- Jul 19, 2017
- Updated
- Jun 16, 2026
- EPSS
- 1.7% · 76th percentile
- CWE
- CWE-125
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Report tools
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 · 1.7%
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| ruby-lang | ruby | cpe:2.3:a:ruby-lang:ruby |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- ruby-lang ruby2.4.1
Same product
ruby-lang: all recordsOther 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 i52Plan
- 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 demons41Plan
- 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.
No fix version is recorded for this entry. Check the references for vendor advisories.
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
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.
No dated events beyond publication.
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 researchersFinders, 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-125 · Out-of-bounds ReadCVSS vector
CVSS:3.0/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.
Attack patterns (CAPEC)
ATT&CK techniques
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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 helpChange log
No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.
References
Vendor advisories and official records. Exploit/PoC links are deliberately left out.