GHSA-wj3h-wx8g-x699 CVE-2024-5986 PYSEC-2026-353
H2O has an External Control of File Name or Path vulnerability
Critical
MavenPyPI
- Severity
- 9.1 / 10
- Critical · CVSS 3.0
- Exploit chance (EPSS)
- 0.70%
- Chance of exploitation in the next 30 days. Higher than 53.33% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-73 External Control of File Name or Path
- Fix
- None yet
- No fixed version published
Description
A vulnerability in h2oai/h2o-3 version 3.46.0.1 allows remote attackers to write arbitrary data to any file on the server. This is achieved by exploiting the /3/Parse endpoint to inject attacker-controlled data as the header of an empty file, which is then exported using the /3/Frames/framename/export endpoint. The impact of this vulnerability includes the potential for remote code execution and complete access to the system running h2o-3, as attackers can overwrite critical files such as private SSH keys or script files.
Affected versions
Maven
| Package | Vulnerable | Fixed in |
|---|---|---|
| ai.h2o:h2o-core | <= 3.46.0.1 |
No fix yet |
PyPI
| Package | Vulnerable | Fixed in |
|---|---|---|
| h2o | <= 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 9.1
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- High
- Availability
- High
Weakness
CWE-73: External Control of File Name or Path
The product allows user input to control or influence paths or file names that are used in filesystem operations.
How to prevent it
- Architecture and Design: When the set of filenames is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames, and reject all other inputs. For example, ID 1 could map to "inbox.txt" and ID 2 could map to "profile.txt". Features such as the ESAPI AccessReferenceMap provide this capability.
- Architecture and Design, Operation: Run your code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict all access to files within a particular directory. Examples include the Unix chroot jail and AppArmor. In general, managed code may provide some protection. This may not be a feasible solution, and it only limits the impact to the operating system; the rest of your application may still be subject to compromise. Be careful to avoid CWE-243 and other weaknesses related to jails.
- Architecture and Design: For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
- Implementation: Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright. When validating filenames, use stringent allowlists that limit the character set to be used. If feasible, only allow a single "." character in the filename to avoid weaknesses such as CWE-23, and exclude directory separators such as "/" to avoid CWE-36. Use a list of allowable file extensions, which will help to avoid CWE-434. Do not rely exclusively on a filtering mechanism that removes potentially dangerous characters. This is equivalent to a denylist, which may be incomplete (CWE-184). For example, filtering "/" is insufficient protection if the filesystem also supports the use of "\" as a directory separator. Another possible error could occur when the filtering is applied in a way that still produces dangerous data (CWE-182). For example, if "../" sequences are removed from the ".../...//" string in a sequential fashion, two instances of "../" would b
- Implementation: Use a built-in path canonicalization function (such as realpath() in C) that produces the canonical version of the pathname, which effectively removes ".." sequences and symbolic links (CWE-23, CWE-59).
- Installation, Operation: Use OS-level permissions and run as a low-privileged user to limit the scope of any successful attack.
- Operation, Implementation: If you are using PHP, configure your application so that it does not use register_globals. During implementation, develop your application so that it does not rely on this feature, but be wary of implementing a register_globals emulation that is subject to weaknesses such as CWE-95, CWE-621, and similar issues.
- Testing: Use tools and techniques that require manual (human) analysis, such as penetration testing, threat modeling, and interactive tools that allow the tester to record and modify an active session. These may be more effective than strictly automated techniques. This is especially the case with weaknesses that are related to design and business rules.
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-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 |
| GHSA-47f6-5p7h-5f3h H2O Vulnerable to Arbitrary File Overwrite via File Export | High | Also affects ai.h2o:h2o-core |
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