Critical Authentication Flaw in dcrypt-symmetric Package: Streaming AEAD Vulnerability
Summary
RUSTSEC-2026-0239: Streaming AEAD does not authenticate stream structure. Affects dcrypt-symmetric versions >= 0.0.0-0, < 2.0.0. Fixed in 2.0.0. How to fix ↓
Check if this vulnerability affects your application
Upload a manifest or SBOM and we'll show whether you're affected, plus every other risky package in the same scan.
No signup required · Results in about 60 seconds
Background
The dcrypt-symmetric package is a Rust library designed for symmetric encryption, providing various authenticated encryption schemes. It supports multiple algorithms, including GCM and ChaCha20-Poly1305, enabling secure data transmission. However, prior to version 2.0.0, the package had a significant vulnerability related to the authentication of stream structures, which could compromise the integrity and confidentiality of encrypted data.
Vulnerability Detail
In all versions of dcrypt-symmetric before 2.0.0, the implementation of version-1 GCM and ChaCha20-Poly1305 streams lacked proper authentication for critical fields such as terminator, counter, and length. This flaw allowed decryptors to trust transmitted counters without verification, leading to potential attacks where an adversary could truncate EOF, omit, replay, or reorder frames within a stream. Additionally, attackers could request allocations nearing 4 GiB, posing a denial-of-service risk. The vulnerability stems from the absence of authenticated structures, making it impossible to ensure the completeness or ordering of existing version-1 ciphertext.
How To Fix
Minimum fixed version
2.0.0
This is the first release that contains the fix.
Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
There are no direct workarounds for this vulnerability. The best course of action is to upgrade to the patched version (2.0.0 or later) to ensure the integrity and security of your encrypted streams.
Conclusion
The dcrypt-symmetric package has a critical vulnerability affecting its streaming AEAD implementation, allowing for potential data manipulation and denial-of-service attacks. Users are strongly advised to upgrade to version 2.0.0 or later to ensure the security of their applications. Utilizing tools like Vulert can help monitor for such vulnerabilities in real-time.
See every vulnerability recorded for dcrypt-symmetric →
FAQ
The vulnerability allows attackers to manipulate the stream structure, potentially leading to data integrity issues and denial-of-service attacks.
You can use the Vulert platform to monitor and alert for open-source vulnerabilities in your software. Visit Vulert Scanner to check if your application is affected without any signup.
While there are no effective workarounds, it is crucial to prioritize upgrading to the patched version as soon as possible to mitigate risks.
Version 2.0.0 introduces the DCRSTRM2 format, which authenticates critical fields and enforces stricter security measures, including bounded lengths and authenticated finality.
Existing version-1 ciphertext cannot be validated for completeness or ordering and must be migrated through a trusted process.
Follow Vulert in Google
Get more Vulert vulnerability and dependency-security updates in Google Search and AI results.