GHSA-g9mf-h72j-4rw9 CVE-2026-22036
Undici has an unbounded decompression chain in HTTP responses on Node.js Fetch API via Content-Encoding leads to resource exhaustion
High
npm
- Severity
- 5.9 / 10
- High · CVSS 3.1
- Exploit chance (EPSS)
- 0.46%
- Chance of exploitation in the next 30 days. Higher than 39.63% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-770 Allocation of Resources Without Limits or Throttling
- Fix
7.18.2- Upgrade undici to this version or later
Description
Impact
The fetch() API supports chained HTTP encoding algorithms for response content according to RFC 9110 (e.g., Content-Encoding: gzip, br). This is also supported by the undici decompress interceptor.
However, the number of links in the decompression chain is unbounded and the default maxHeaderSize allows a malicious server to insert thousands compression steps leading to high CPU usage and excessive memory allocation.
Patches
Upgrade to 7.18.2 or 6.23.0.
Workarounds
It is possible to apply an undici interceptor and filter long Content-Encoding sequences manually.
References
Affected versions
npm
| Package | Vulnerable | Fixed in |
|---|---|---|
| undici | >= 7.0.0, < 7.18.2 |
7.18.2 |
| undici | < 6.23.0 |
6.23.0 |
| undici | >= 7.0.0, < 7.18.2 |
7.18.2 |
| undici | < 6.23.0 |
6.23.0 |
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.
undici npm → 7.18.2
- npm
npm install undici@7.18.2- yarn
yarn add undici@7.18.2- pnpm
pnpm add undici@7.18.2
Severity breakdown
CVSS 3.1 5.9
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
- Attack vector
- Network
- Attack complexity
- High
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Weakness
CWE-770: Allocation of Resources Without Limits or Throttling
The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.
How to prevent it
- Requirements: Clearly specify the minimum and maximum expectations for capabilities, and dictate which behaviors are acceptable when resource allocation reaches limits.
- Architecture and Design: Limit the amount of resources that are accessible to unprivileged users. Set per-user limits for resources. Allow the system administrator to define these limits. Be careful to avoid CWE-410.
- 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, and it will help the administrator to identify who is committing the abuse. 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.
- 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.
- 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.
- 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, typically by using increasing time delays 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 can be difficult to effectively institute -- and even when properly done, it does not provide a full solution. It simply requires more resources on the part of the attacker.
- Architecture and Design: Ensure that protocols have specific limits of scale placed on them.
- Architecture and Design, Implementation: If the program must fail, ensure that it fails gracefully (fails closed). There may be a temptation to simply let the program fail poorly in cases such as low memory conditions, but an attacker may be able to assert control before the software has fully exited. Alternately, an uncontrolled failure could cause cascading problems with other downstream components; for example, the program could send a signal to a downstream process so the process immediately knows that a problem has occurred and has a better chance of recovery. Ensure that all failures in resource allocation place the system into a safe posture.
- Operation, Architecture and Design: Use quotas or other resource-limiting settings provided by the operating system or environment. For example, when managing system resources in POSIX, setrlimit() can be used to set limits for certain types of resources, and getrlimit() can determine how many resources are available. However, these functions are not available on all operating systems. When the current levels get close to the maximum that is defined for the application (see CWE-770), then limit the allocation of further resources to privileged users; alternately, begin releasing resources for less-privileged users. While this mitigation may protect the system from attack, it will not necessarily stop attackers from adversely impacting other users. Ensure that the application performs the appropriate error checks and error handling in case resources become unavailable (CWE-703).
References
Advisories
Fixes and patches
Packages
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-55wc-3pg8-jfw6 undici vulnerable to Denial of Service via unhandled exception in the decompress interceptor | High | Also affects undici |
| GHSA-qrxm-fqhp-jwvm undici vulnerable to Denial of Service via TLS 1.2 certificate-changing renegotiation | High | Also affects undici |
| GHSA-9fm3-97px-rjf6 undici WebSocket client vulnerable to Denial of Service via unbounded automatic PONG buffering | High | Also affects undici |
| GHSA-4qv8-2p9j-2685 undici vulnerable to Denial of Service via unbounded memory in the EventSource parser | High | Also affects undici |
| GHSA-xjj6-f33q-929c undici vulnerable to Denial of Service via unhandled error on excessive content-encodings | High | Also affects undici |
| GHSA-f72v-6w45-q472 undici vulnerable to Subresource Integrity bypass via non-lowercase algorithm tokens | High | Also affects undici |
| GHSA-4w7w-5xrc-9h26 undici vulnerable to cache poisoning and cross-user disclosure via cross-origin redirects | Critical | Also affects undici |
| GHSA-2m5v-pch6-74hx undici vulnerable to TLS certificate validation bypass via dropped tls options in Agent | Critical | Also affects undici |
Credits: illia-v, mcollina
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