GHSA-qhcq-9pm2-c9w9 CVE-2026-113658
ApostropheCMS: Unauthenticated CSV import requests leave rejected uploads in the system temporary directory
- Severity
- 7.5 / 10
- High · CVSS 3.1
- Exploit chance (EPSS)
- 0.61%
- Chance of exploitation in the next 30 days. Higher than 49.47% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-400 Uncontrolled Resource Consumption
- CWE-459 Incomplete Cleanup
- CWE-770 Allocation of Resources Without Limits or Throttling
- Fix
4.33.0- Upgrade apostrophe to this version or later
Description
Summary
A rejected upload can remain in the operating system temporary directory.
Multer writes the file before its extension is checked, and the rejection path does not remove that temporary file. An unauthenticated requester can repeat this with large files and steadily consume temporary disk space.
Details
The endpoint is:
POST /api/v1/@apostrophecms/rich-text-widget/generate-csv-table
In packages/apostrophe/modules/@apostrophecms/rich-text-widget/lib/apiRoutes.js, Multer first writes the upload to os.tmpdir(). The handler then rejects filenames whose extension is not csv, but there is no cleanup of the Multer file on this error path.
The route does not require an authenticated user. A normal CSRF cookie is sufficient.
During testing, the request returned HTTP 400 with Only csv files are supported, while the complete uploaded content remained in a randomly named file in the configured temporary directory after the response.
Relationship to prior public work
I reviewed PR #5013, which migrated the Rich Text CSV upload path from connect-multiparty to Multer. This report concerns cleanup after that migration: the rejected Multer file remains on disk, a behavior not described in the PR or its review discussion.
POC
Create a small test file. A larger file can be used to demonstrate disk growth, but 1 MiB is enough for a safe local reproduction:
dd if=/dev/zero of=rejected.txt bs=1M count=1
Obtain the normal site cookies and send the rejected upload:
curl -c cookies.txt 'http://127.0.0.1:3000/' > /dev/null
curl -i -b cookies.txt \
-F 'file=@rejected.txt;filename=rejected.txt;type=text/plain' \
'http://127.0.0.1:3000/api/v1/@apostrophecms/rich-text-widget/generate-csv-table'
The response is HTTP 400. Compare the contents of the system temporary directory before and after the request:
ls -lt /tmp
A new randomly named file remains present and contains the uploaded bytes.
No login is required. Repeating the multipart request creates additional persistent temporary files.
Impact
A remote unauthenticated attacker can fill the partition used by the operating system temporary directory. Once that partition is exhausted, Apostrophe and unrelated services on the same host may fail to upload files, create temporary data, or continue operating normally.
The attack requires only repeated HTTP requests and the stored files remain after each rejected response.
Affected versions
npm
| Package | Vulnerable | Fixed in |
|---|---|---|
| apostrophe | < 4.33.0 |
4.33.0 |
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.
apostrophe npm → 4.33.0
- npm
npm install apostrophe@4.33.0- yarn
yarn add apostrophe@4.33.0- pnpm
pnpm add apostrophe@4.33.0
Severity breakdown
CVSS 3.1 7.5
CVSS:3.1/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-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.
CWE-459: Incomplete Cleanup
The product does not properly "clean up" and remove temporary or supporting resources after they have been used.
How to prevent it
- Architecture and Design, Implementation: Temporary files and other supporting resources should be deleted/released immediately after they are no longer needed.
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
Packages
Other links
- github.com/apostrophecms/apostrophe/security/advisories/GHSA-qhcq-9pm2-c9w9
- github.com/apostrophecms/apostrophe/commit/9500b8b0e1d630d5e07fbb5fd2c25ed09438…
- github.com/apostrophecms/apostrophe/commit/f84fd41cbf6c22eb8d0008fc9c25df1f7130…
- github.com/apostrophecms/apostrophe/releases/tag/apostrophe@4.33.0
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-86wm-68pq-5jwq ApostropheCMS: Unauthenticated resource exhaustion via pre-auth aposBigUpload processing in @apostrophecms/import-export | High | Also affects apostrophe |
| GHSA-653j-g8j7-gh54 ApostropheCMS: No Attempt Throttling on Authenticated Password-Change Endpoint Enables Unlimited Current-Password Guessing | Medium | Also affects apostrophe |
| GHSA-vwwx-px9w-crrc ApostropheCMS: Missing Authorization on Notification PATCH/DELETE Endpoints | Low | Also affects apostrophe |
| GHSA-vmxh-77cw-65j7 ApostropheCMS: Authenticated Object-Level Authorization Bypass in exist-in-locale Reveals Restricted Localized Draft Identifiers | Medium | Also affects apostrophe |
| GHSA-m2m5-rw3w-cwmj ApostropheCMS: Client-side Prototype Pollution in apos.http.parseQuery leading to DOM-based XSS against authenticated users | Medium | Also affects apostrophe |
| GHSA-gqh3-7856-rjjg ApostropheCMS: :_id/locales REST route omits the public-API authorization gate its sibling read routes enforce (unauthenticated doc-existence + locale metadata disclosure) | Medium | Also affects apostrophe |
| GHSA-hhvr-8m24-qqr3 ApostropheCMS: Cross-domain session token in URL confers session takeover | Medium | Also affects apostrophe |
| GHSA-j5rq-xfvr-p969 ApostropheCMS: Authenticated projection-exclusion prototype-member deletion in @apostrophecms/db-connect causes process-wide denial of service | High | Also affects apostrophe |
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