Heap overwrite via mutable Psych tag array
Published Feb 14, 2020 · Updated Aug 5, 2024
Heap overflow in Ruby 2.2.2 and 2.3.0 dev allows attackers to write beyond a heap allocation via crafted Psych tags. Psych::Emitter#start_document sizes head once from the tags array, but StringValuePtr invokes attacker-defined to_str code that can enlarge that array before the loop ends. Exploitation requires a non-String UTF-8-encoded object with a to_str method inside a tag tuple; the published demonstration corrupts the heap and crashes Ruby.
Summary
What happened
Heap overflow in Ruby 2.2.2 and 2.3.0 dev allows attackers to write beyond a heap allocation via crafted Psych tags. Psych::Emitter#start_document sizes head once from the tags array, but StringValuePtr invokes attacker-defined to_str code that can enlarge that array before the loop ends. Exploitation requires a non-String UTF-8-encoded object with a to_str method inside a tag tuple; the published demonstration corrupts the heap and crashes Ruby.
The record
- CVE
- CVE-2016-2338
- Published
- Feb 14, 2020
- Updated
- Aug 5, 2024
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-787
- Attack vector
- Unavailable
- Privileges
- Unavailable
Timeline
How it unfolded
- Feb 14, 2020CVE publishedPublication date reported by the CVE source.
- Aug 5, 2024Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
What conditions does exploitation require?
What is affected?
Affected products and versions are unavailable in this record.
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Cisco Talos Psych::Emitter start_document proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo