Executive brief
A security flaw was found in a Netty library used for processing encrypted HTTP messages. When certain cryptographic operations fail, the system incorrectly continues using a default 'all-zero' key instead of stopping with an error. This allows an attacker to predict the encryption keys used for responses, potentially allowing them to decrypt or tamper with secure communications.
Technical details
A vulnerability exists in the Netty incubator codec.bhttp (OHTTP) where HKDF_expand and EVP_HPKE_CTX_export return a non-NULL byte array filled with zeros upon failure rather than throwing an exception. This zeroed output is subsequently used as key material for the response Authenticated Encryption with Associated Data (AEAD). Because the failure is silent, the system generates a deterministic, attacker-predictable AEAD key. This issue stems from insufficient error signaling in the native HPKE implementation. The vulnerability is resolved in version 0.0.21.Final by ensuring these methods throw a CryptoException on failure.
Affected products
- Netty Project netty-incubator-codec-ohttp < 0.0.21.Final
Timeline
- 2026-05-06: patched: Fix committed to repository
- 2026-05-20: advisory: GitHub Security Advisory published
- 2026-06-04: disclosed: CVE published to NVD