CVE-2026-24785: Clatter Rust Noise library: PSK validity violation in post-quantum handshake patterns
CVE-2026-24785 affects Clatter, a Rust implementation of the Noise protocol framework with post-quantum support, in versions before 2.2.0. The library accepted post-quantum handshake patterns that break the PSK validity rule, which can lead to PSK-derived keys being used for encryption without proper ephemeral randomness. The issue is fixed in v2.2.0, which adds runtime checks, and no confirmed active exploitation appears in the sources consulted.
Overview
CVE-2026-24785 is a protocol compliance flaw in Clatter, a pure Rust, no_std compatible implementation of the Noise protocol framework with post-quantum support. According to the record, versions before 2.2.0 allowed post-quantum handshake patterns that violate the PSK validity rule defined by the Noise specification. The Noise validity rule is the reference for the expected behavior.
Impact
The record states that this could allow PSK-derived keys to be used for encryption without proper randomization from ephemeral randomness chosen by the handshake participants. This may weaken the intended security guarantees and could potentially lead to catastrophic key reuse. The NVD score is 9.1 under CVSS 3.1 with high confidentiality and integrity impact, and the CNA score is 8 under CVSS 4.0.
Affected products and versions
- Product: Jmlepisto Clatter
- Affected range: versions before 2.2.0
- Fixed version: 2.2.0, which the record says includes runtime checks that detect offending handshake patterns
- Affected default patterns named in the record: noise_pqkk_psk0, noise_pqkn_psk0, noise_pqnk_psk0, noise_pqnn_psk0, and some hybrid variants
The record does not give a complete list of hybrid variants, so the exact scope beyond the named patterns is unknown.
Exploitation status
The CISA KEV catalog does not list this CVE in the record, so no confirmed active exploitation is reported. No confirmed exploitation appears in the sources consulted for this analysis.
Remediation and mitigation
- Upgrade Clatter to version 2.2.0 or later, as stated in the GitHub security advisory. The fix commit is listed as the patch.
- Avoid the offending PSK-based variants of post-quantum patterns until the upgrade is in place, as the record suggests as a workaround.
- Review any custom handshake patterns carefully against the validity rule, since the record notes that custom patterns may also be affected.
Detection guidance
- Inventory applications and services that depend on Clatter and record the exact version in use, especially any version below 2.2.0.
- Review configuration and code for the handshake pattern names listed above and for custom patterns that combine post-quantum key exchange with PSK modes.
- After upgrading, confirm that the runtime checks in version 2.2.0 are active and that offending patterns are rejected in testing.
Limitations of the available information
The record does not include EPSS or SSVC data, so exploitation likelihood is unknown. It does not describe a proof of concept or real-world incidents. The full list of affected hybrid variants and custom patterns is not specified, and the record contains a few typographical inconsistencies in the version and pattern names. Specific deployment impact depends on how each application uses Clatter.
Frequently asked questions
Which versions of Clatter are affected by CVE-2026-24785?
The record lists Clatter versions before 2.2.0 as affected. Version 2.2.0 is the fixed release named in the GitHub advisory and the fix commit.
Is this vulnerability known to be actively exploited?
No. The CISA KEV catalog does not list this CVE in the record, and no confirmed exploitation appears in the sources consulted.
What is the recommended action for users?
Upgrade Clatter to version 2.2.0 or later, avoid the offending PSK-based post-quantum patterns until upgraded, and review any custom handshake patterns against the Noise validity rule.
This analysis was drafted with AI assistance from verified source data and automatically checked against it.