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RUSTSEC-2026-0071

CriticalCVSS 9.3 / 10
Published Feb 5, 2026·Last modified Mar 24, 2026
Affected Components(0)

No affected components available

Description

The sequence number that is used to compute the AEAD nonce when using a re-usable HPKE context is incremented after each seal or open operation. This sequence number was stored as a u32 and used regular addition on u32 for the increment, meaning in release mode it would silently wrap around to 0 after 2^32 seal or open operations.

Impact

Nonce reuse causes catastrophic breakage of AEAD ciphers, enabling plaintext recovery attacks and authentication tag forgeries, depending on the concrete AEAD.

This bug impacts applications that use hpke-rs to encrypt a large number of messages using the same context. Applications using the one-shot APIs are unaffected.

Mitigation

Starting with version 0.6.0, checked_add is used to increment the sequence number, which avoids a silent wraparound in release mode. Additionally, the sequence number is now stored as a u64, increasing the maximally allowed number of seal and open operations on a given HPKE context.

Risk Scores
Base Score
9.3

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability.

Threat Intelligence
8.0

Exploitation activity has been observed. Apply available patches or mitigations urgently.

EPSS
N/A

Probability that this vulnerability will be exploited in the wild within the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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