Client hang via nested DateTime regex repetition
Published Jul 12, 2021 · Updated Aug 3, 2024
Regular expression denial of service in RestSharp before 106.11.8-alpha.0.13 allows remote attackers to hang clients via crafted responses. The NewDateRegex in RestSharp.Extensions.StringExtensions uses nested repetition around a digit group, causing exponential backtracking when ParseJsonDate processes digits without a closing parenthesis. Exploitation requires a client to deserialize an attacker-controlled JSON response into a class with a DateTime property, consuming a processing thread for an exceedingly long time.
Summary
What happened
Regular expression denial of service in RestSharp before 106.11.8-alpha.0.13 allows remote attackers to hang clients via crafted responses. The NewDateRegex in RestSharp.Extensions.StringExtensions uses nested repetition around a digit group, causing exponential backtracking when ParseJsonDate processes digits without a closing parenthesis. Exploitation requires a client to deserialize an attacker-controlled JSON response into a class with a DateTime property, consuming a processing thread for an exceedingly long time.
The record
- CVE
- CVE-2021-27293
- Published
- Jul 12, 2021
- Updated
- Aug 3, 2024
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-185, CWE-697, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 12, 2021CVE publishedPublication date reported by the CVE source.
- Aug 3, 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
- Doyensec RestSharp ReDoS reproductionproof 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