GHSA-wwr9-4gmr-xvq9 CVE-2024-10549 PYSEC-2026-1445
H2O Vulnerable to Denial of Service (DoS) via `/3/Parse` Endpoint
- Severity
- 7.5 / 10
- High · CVSS 3.0
- Exploit chance (EPSS)
- 0.64%
- Chance of exploitation in the next 30 days. Higher than 50.52% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Fix
- None yet
- No fixed version published
Description
A vulnerability in the /3/Parse endpoint of h2oai/h2o-3 version 3.46.0.1 allows for a denial of service (DoS) attack. The endpoint uses a user-specified string to construct a regular expression, which is then applied to another user-specified string. By sending multiple simultaneous requests, an attacker can exhaust all available threads, leading to a complete denial of service.
Affected versions
Maven
| Package | Vulnerable | Fixed in |
|---|---|---|
| ai.h2o:h2o-core | >= 3.30.0.7, <= 3.46.0.1 |
No fix yet |
PyPI
| Package | Vulnerable | Fixed in |
|---|---|---|
| h2o | >= 3.30.0.7, <= 3.46.0.1 |
No fix yet |
How to fix
No fixed version has been published yet. Until one is, remove or replace the package, or turn off or isolate the affected feature. This page updates when a fix ships.
Severity breakdown
CVSS 3.0 7.5
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Weakness
CWE-1333: Inefficient Regular Expression Complexity
The product uses a regular expression with a worst-case computational complexity that is inefficient and possibly exponential.
How to prevent it
- Architecture and Design: Use regular expressions that do not support backtracking, e.g. by removing nested quantifiers.
- System Configuration: Set backtracking limits in the configuration of the regular expression implementation, such as PHP's pcre.backtrack_limit. Also consider limits on execution time for the process.
- Implementation: Do not use regular expressions with untrusted input. If regular expressions must be used, avoid using backtracking in the expression.
- Implementation: Limit the length of the input that the regular expression will process.
CWE-400: Uncontrolled Resource Consumption
The product does not properly control the allocation and maintenance of a limited resource.
How to prevent it
- Architecture and Design: Design throttling mechanisms into the system architecture. The best protection is to limit the amount of resources that an unauthorized user can cause to be expended. A strong authentication and access control model will help prevent such attacks from occurring in the first place. The login application should be protected against DoS attacks as much as possible. Limiting the database access, perhaps by caching result sets, can help minimize the resources expended. To further limit the potential for a DoS attack, consider tracking the rate of requests received from users and blocking requests that exceed a defined rate threshold.
- Architecture and Design: Mitigation of resource exhaustion attacks requires that the target system either: recognizes the attack and denies that user further access for a given amount of time, or uniformly throttles all requests in order to make it more difficult to consume resources more quickly than they can again be freed. The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question. The second solution is simply difficult to effectively institute -- and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.
- Architecture and Design: Ensure that protocols have specific limits of scale placed on them.
- Implementation: Ensure that all failures in resource allocation place the system into a safe posture.
References
Advisories
Packages
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-qmcv-hh7c-3m56 H2O-3 is Vulnerable to Code Injection | Critical | Also affects ai.h2o:h2o-core |
| GHSA-wj3h-wx8g-x699 H2O has an External Control of File Name or Path vulnerability | Critical | Also affects ai.h2o:h2o-core |
| GHSA-5w3j-gwgh-4rfv H2O affected by a deserialization vulnerability | Critical | Also affects ai.h2o:h2o-core |
| GHSA-g48v-3p35-88jr H2O Vulnerable to Arbitrary File Overwrite | High | Also affects ai.h2o:h2o-core |
| GHSA-5c8j-g96x-cj78 H2O Vulnerable to Denial of Service (DoS) via `HEAD` Request | High | Also affects ai.h2o:h2o-core |
| GHSA-p2vc-m5fv-9w9m H2O Vulnerable to Denial of Service (DoS) via `/3/ImportFiles` Endpoint | High | Also affects ai.h2o:h2o-core |
| GHSA-6w62-3jvj-mfj6 H2O Vulnerable to Denial of Service (DoS) via Large GZIP Parsing | High | Also affects ai.h2o:h2o-core |
| GHSA-m37h-8r48-2cxj H2O Vulnerable to Execution of Arbitrary Files | Medium | Also affects ai.h2o:h2o-core |
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