GHSA-75px-5xx7-5xc7 CVE-2026-44291
protobuf.js: Code generation gadget after prototype pollution
- Severity
- 8.1 / 10
- High · CVSS 3.1
- Exploit chance (EPSS)
- 0.50%
- Chance of exploitation in the next 30 days. Higher than 42.84% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-1321 Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
- CWE-94 Improper Control of Generation of Code ('Code Injection')
- Fix
7.5.6- Upgrade protobufjs to this version or later
Description
Summary
protobufjs used plain objects with inherited prototypes for internal type lookup tables used by generated encode and decode functions. If Object.prototype had already been polluted, those lookup tables could resolve attacker-controlled inherited properties as valid protobuf type information.
This could cause attacker-controlled strings to be emitted into generated JavaScript code.
Impact
An attacker who can first trigger a prototype pollution vulnerability may be able to influence generated protobufjs encode or decode functions in a way that can lead to arbitrary JavaScript execution.
This issue requires a separate prototype pollution primitive before protobufjs is invoked.
Applications without a reachable prototype pollution primitive are not directly exploitable through this issue alone.
Preconditions
- The application or one of its dependencies must allow an attacker to pollute
Object.prototype. - The polluted property must affect protobufjs internal type lookup behavior.
- The application must use protobufjs functionality that generates encode or decode code for affected types.
- The generated code path must be reached after the prototype pollution has occurred.
Workarounds
Avoid running affected versions in applications where attacker-controlled input can pollute Object.prototype. If immediate upgrade is not possible, remove or mitigate reachable prototype pollution primitives and isolate schema/message processing from untrusted application state.
Affected versions
npm
| Package | Vulnerable | Fixed in |
|---|---|---|
| protobufjs | < 7.5.6 |
7.5.6 |
| protobufjs | >= 8.0.0, < 8.0.2 |
8.0.2 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
protobufjs npm → 7.5.6
- npm
npm install protobufjs@7.5.6- yarn
yarn add protobufjs@7.5.6- pnpm
pnpm add protobufjs@7.5.6
Severity breakdown
CVSS 3.1 8.1
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- Attack vector
- Network
- Attack complexity
- High
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Weakness
CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.
How to prevent it
- Implementation: By freezing the object prototype first (for example, Object.freeze(Object.prototype)), modification of the prototype becomes impossible.
- Architecture and Design: By blocking modifications of attributes that resolve to object prototype, such as proto or prototype, this weakness can be mitigated.
- Implementation: When handling untrusted objects, validating using a schema can be used.
- Implementation: By using an object without prototypes (via Object.create(null) ), adding object prototype attributes by accessing the prototype via the special attributes becomes impossible, mitigating this weakness.
- Implementation: Map can be used instead of objects in most cases. If Map methods are used instead of object attributes, it is not possible to access the object prototype or modify it.
CWE-94: Improper Control of Generation of Code ('Code Injection')
The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.
How to prevent it
- Architecture and Design: Refactor your program so that you do not have to dynamically generate code.
- Architecture and Design: 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 which code can be executed by your product. 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.
- 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. To reduce the likelihood of code injection, use stringent allowlists that limit which constructs are allowed. If you are dynamically constructing code that invokes a function, then verifying that the input is alphanumeric might be insufficient. An attacker might still be able to reference a dangerous function that you did not intend to allow, such as system(), exec(), or exit().
- Testing: Use dynamic tools and techniques that interact with the product using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The product's operation may slow down, but it should not become unstable, crash, or generate incorrect results.
- Operation: Run the code in an environment that performs automatic taint propagation and prevents any command execution that uses tainted variables, such as Perl's "-T" switch. This will force the program to perform validation steps that remove the taint, although you must be careful to correctly validate your inputs so that you do not accidentally mark dangerous inputs as untainted (see CWE-183 and CWE-184).
- Operation: Run the code in an environment that performs automatic taint propagation and prevents any command execution that uses tainted variables, such as Perl's "-T" switch. This will force the program to perform validation steps that remove the taint, although you must be careful to correctly validate your inputs so that you do not accidentally mark dangerous inputs as untainted (see CWE-183 and CWE-184).
- Implementation: For Python programs, it is frequently encouraged to use the ast.literal_eval() function instead of eval, since it is intentionally designed to avoid executing code. However, an adversary could still cause excessive memory or stack consumption via deeply nested structures [REF-1372], so the python documentation discourages use of ast.literal_eval() on untrusted data [REF-1373].
References
Advisories
Packages
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-j3f2-48v5-ccww protobufjs: Denial of Service via infinite loop in .proto option parsing | High | Also affects protobufjs |
| GHSA-jfj6-75fj-8934 protobufjs: Text Format string map parsing can mutate returned map object prototype | Medium | Also affects protobufjs |
| GHSA-94rc-8x27-4472 protobufjs: Memory amplification from preserved unknown fields in binary decode | Medium | Also affects protobufjs |
| GHSA-wcpc-wj8m-hjx6 protobufjs: Denial of service through unbounded Any expansion during JSON conversion | High | Also affects protobufjs |
| GHSA-f38q-mgvj-vph7 protobufjs : Schema-derived names can shadow runtime-significant properties | Medium | Also affects protobufjs |
| GHSA-jggg-4jg4-v7c6 protobufjs: Denial of Service via unbounded recursive JSON descriptor expansion | High | Also affects protobufjs |
| GHSA-2pr8-phx7-x9h3 protobuf.js: Denial of service from crafted field names in generated code | Medium | Also affects protobufjs |
| GHSA-66ff-xgx4-vchm protobuf.js: Code injection through bytes field defaults in generated toObject code | High | Also affects protobufjs |
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