CVE-2026-84366 Vulnerability Analysis & Exploit Details

CVE-2026-84366 Vulnerability Summary

CVE-2026-84366: Scrapy is a high-level web crawling and scraping framework for Python. Prior to 2.17.0, in scrapy/core/downloader/handlers/s3.py, Scrapy's S3DownloadHandler converts an S3-scheme bucket and key request into a plaintext HTTP request to the corresponding S3 endpoint unless request.meta["is_secure"] is explicitly enabled, then signs and sends the plaintext request with configured AWS credentials. A network attacker who can observe traffic between Scrapy and S3 can read the bucket and key path, AWS Authorization header, X-Amz-Security-Token when temporary credentials are used, S3 object contents, and S3 response headers. An active man-in-the-middle attacker can also modify the plaintext S3 response body, status code, and headers before Scrapy processes them, causing scraped-data poisoning, poisoned exports, HTTP cache poisoning when caching is enabled, or influence over later crawl targets through forged redirects or attacker-controlled links. Users making S3-scheme requests with AWS credentials are affected. This issue is fixed in version 2.17.0.

CVE-2026-84366 References

External References

• https://github.com/scrapy/scrapy/commit/9523e1ec8c41fde265a26d14563d178b6f1ad04b
• https://github.com/scrapy/scrapy/releases/tag/2.17.0
• https://github.com/scrapy/scrapy/security/advisories/GHSA-76g3-c3x4-crvx

CWE Common Weakness Enumeration

CAPEC Common Attack Pattern Enumeration and Classification

• Session Sidejacking CAPEC-102 Session sidejacking takes advantage of an unencrypted communication channel between a victim and target system. The attacker sniffs traffic on a network looking for session tokens in unencrypted traffic. Once a session token is captured, the attacker performs malicious actions by using the stolen token with the targeted application to impersonate the victim. This attack is a specific method of session hijacking, which is exploiting a valid session token to gain unauthorized access to a target system or information. Other methods to perform a session hijacking are session fixation, cross-site scripting, or compromising a user or server machine and stealing the session token.
• Interception CAPEC-117 An adversary monitors data streams to or from the target for information gathering purposes. This attack may be undertaken to solely gather sensitive information or to support a further attack against the target. This attack pattern can involve sniffing network traffic as well as other types of data streams (e.g. radio). The adversary can attempt to initiate the establishment of a data stream or passively observe the communications as they unfold. In all variants of this attack, the adversary is not the intended recipient of the data stream. In contrast to other means of gathering information (e.g., targeting data leaks), the adversary must actively position themself so as to observe explicit data channels (e.g. network traffic) and read the content. However, this attack differs from a Adversary-In-the-Middle (CAPEC-94) attack, as the adversary does not alter the content of the communications nor forward data to the intended recipient.
• Harvesting Information via API Event Monitoring CAPEC-383 An adversary hosts an event within an application framework and then monitors the data exchanged during the course of the event for the purpose of harvesting any important data leaked during the transactions. One example could be harvesting lists of usernames or userIDs for the purpose of sending spam messages to those users. One example of this type of attack involves the adversary creating an event within the sub-application. Assume the adversary hosts a "virtual sale" of rare items. As other users enter the event, the attacker records via AiTM (CAPEC-94) proxy the user_ids and usernames of everyone who attends. The adversary would then be able to spam those users within the application using an automated script.
• Signature Spoofing by Mixing Signed and Unsigned Content CAPEC-477 An attacker exploits the underlying complexity of a data structure that allows for both signed and unsigned content, to cause unsigned data to be processed as though it were signed data.
• Sniff Application Code CAPEC-65 An adversary passively sniffs network communications and captures application code bound for an authorized client. Once obtained, they can use it as-is, or through reverse-engineering glean sensitive information or exploit the trust relationship between the client and server. Such code may belong to a dynamic update to the client, a patch being applied to a client component or any such interaction where the client is authorized to communicate with the server.

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