CVE-2024-36121

netty-incubator-codec-ohttp is the OHTTP implementation for netty. BoringSSLAEADContext keeps track of how many OHTTP responses have been sent and uses this sequence number to calculate the appropriate nonce to use with the encryption algorithm. Unfortunately, two separate errors combine which would allow an attacker to cause the sequence number to overflow and thus the nonce to repeat.

netty-incubator-codec-ohttp is the OHTTP implementation for netty. BoringSSLAEADContext keeps track of how many OHTTP responses have been sent and uses this sequence number to calculate the appropriate nonce to use with the encryption algorithm. Unfortunately, two separate errors combine which would allow an attacker to cause the sequence number to overflow and thus the nonce to repeat.

### Summary BoringSSLAEADContext keeps track of how many OHTTP responses have been sent and uses this sequence number to calculate the appropriate nonce to use with the encryption algorithm. Unfortunately, two separate errors combine which would allow an attacker to cause the sequence number to overflow and thus the nonce to repeat. ### Details 1. There is no overflow detection or enforcement of the maximum sequence value. (This is a missed requirement from the draft Chunked Oblivious OHTTP RFC and so should be inherited from the HPKE RFC 9180, Section 5.2). 2. The sequence number (seq) is stored as 32-bit int which is relatively easy to overflow. https://github.com/netty/netty-incubator-codec-ohttp/blob/1ddadb6473cd3be5491d114431ed4c1a9f316001/codec-ohttp-hpke-classes-boringssl/src/main/java/io/netty/incubator/codec/hpke/boringssl/BoringSSLAEADContext.java#L112-L114 ### Impact If the BoringSSLAEADContext is used to encrypt more than 2^32 messages then the AES-GCM nonce will repeat. Repeating a nonce with AES-GCM results in both confidentiality and integrity compromise of data encrypted with the associated key.

### Summary BoringSSLAEADContext keeps track of how many OHTTP responses have been sent and uses this sequence number to calculate the appropriate nonce to use with the encryption algorithm. Unfortunately, two separate errors combine which would allow an attacker to cause the sequence number to overflow and thus the nonce to repeat. ### Details 1. There is no overflow detection or enforcement of the maximum sequence value. (This is a missed requirement from the draft Chunked Oblivious OHTTP RFC and so should be inherited from the HPKE RFC 9180, Section 5.2). 2. The sequence number (seq) is stored as 32-bit int which is relatively easy to overflow. https://github.com/netty/netty-incubator-codec-ohttp/blob/1ddadb6473cd3be5491d114431ed4c1a9f316001/codec-ohttp-hpke-classes-boringssl/src/main/java/io/netty/incubator/codec/hpke/boringssl/BoringSSLAEADContext.java#L112-L114 ### Impact If the BoringSSLAEADContext is used to encrypt more than 2^32 messages then the AES-GCM nonce will repeat. Repeating a nonce with AES-GCM results in both confidentiality and integrity compromise of data encrypted with the associated key.

netty-incubator-codec-ohttp es la implementación OHTTP para netty. BoringSSLAEADContext realiza un seguimiento de cuántas respuestas OHTTP se han enviado y utiliza este número de secuencia para calcular el nonce apropiado para usar con el algoritmo de cifrado. Desafortunadamente, se combinan dos errores separados que permitirían a un atacante provocar que el número de secuencia se desborde y, por lo tanto, que se repita el nonce.