VulnerabilityPublished 29 Sep 2026Updated 30 Sep 2026

CVE-2026-102824: Eugeny russh · Weak Cryptography

Affects Eugeny russhSource CVE Database V5

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Not known to be exploited · CVSS 4.3 Medium : upgrade to 0.63.0 when convenient.

Data as of 12 Nov 2026, 23:24 UTC

CVSS 3.1 base score

4.3Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.1% chance of exploitation in 30 days – higher than 3% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 0.63.0

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: Low
User Interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: None
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 29 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 13 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade russh and github/Eugeny/russh to 0.63.0.

Affected software

Product	Affected	Fixed in
Eugenyrussh	Affected <0.63.0	Fixed in 0.63.0
crates.iogithub/Eugeny/russh`pkg:cargo/github/Eugeny/russh`Other threats	Affected <0.63.0	Fixed in 0.63.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade russh to version 0.63.0 or later, where this vulnerability is fixed. No other mitigation is required as the fix addresses the root cause by rejecting all-zero X25519 public keys.

Description

CVE-2026-102824 affects the Eugeny russh Rust SSH client and server library prior to version 0.63.0. The vulnerability arises from the hybrid ML-KEM 768 and X25519 key exchange implementation accepting an all-zero 32-byte peer X25519 public key. This causes the X25519 contribution to the combined shared secret to be zero, allowing a malicious peer to force the shared secret to depend solely on ML-KEM. This defeats the intended fallback protection of the hybrid exchange. The issue is fixed in russh version 0.63.0.

Impact

A malicious SSH peer can exploit this vulnerability by sending an all-zero X25519 public key, causing the shared secret to depend solely on the ML-KEM algorithm. This undermines the hybrid key exchange's fallback protection, potentially weakening the cryptographic strength of the SSH session if ML-KEM is compromised or weakened in the future. The confidentiality of the SSH session could be partially impacted, but there is no direct impact on integrity or availability reported.

Summary

In russh versions before 0.63.0, the hybrid ML-KEM 768 and X25519 key exchange implementation in russh/src/kex/hybrid_mlkem.rs improperly accepts an all-zero 32-byte X25519 public key from a peer. This acceptance causes the X25519 component of the combined shared secret to be zeroed out, effectively removing its cryptographic contribution. Consequently, the combined shared secret relies only on the ML-KEM component, undermining the hybrid key exchange's fallback security if ML-KEM is weakened in the future. This cryptographic flaw is classified under CWE-327 (Use of a Broken or Risky Cryptographic Algorithm). The vulnerability has a CVSS 3.1 base score of 4.3 (medium severity) and was published on 2026-09-29. The issue is resolved in russh version 0.63.0.

CWE-327Use of a Broken or Risky Cryptographic Algorithm (opens in a new tab)
Class weaknessLikelihood of exploit: HighOWASP Top 10 A04:2025: Cryptographic Failures (opens in a new tab)
The product uses a broken or risky cryptographic algorithm or protocol.
Architecture and Design · Libraries or Frameworks
When there is a need to store or transmit sensitive data, use strong, up-to-date cryptographic algorithms to encrypt that data. Select a well-vetted algorithm that is currently considered to be strong by experts in the field, and use well-tested implementations.
Architecture and Design
Ensure that the design allows one cryptographic algorithm to be replaced with another in the next generation or version. Where possible, use wrappers to make the interfaces uniform. This will make it easier to upgrade to stronger algorithms.
Architecture and Design
Carefully manage and protect cryptographic keys (see CWE-320). If the keys can be guessed or stolen, then the strength of the cryptography itself is irrelevant.
OWASP Cheat Sheets
Cryptographic Storage (opens in a new tab)
Key Management (opens in a new tab)
Transport Layer Protection (opens in a new tab)
User Privacy Protection (opens in a new tab)
Password Storage (opens in a new tab)
OWASP ASVS 4.0.3
V8.3.7 (opens in a new tab)
V2.9.3 (opens in a new tab)
V6.2.2 (opens in a new tab)
Attack patterns
Encryption Brute Forcing (opens in a new tab)
Creating a Rogue Certification Authority Certificate (opens in a new tab)
Signature Spoof (opens in a new tab)
Signature Spoofing by Improper Validation (opens in a new tab)
Cryptanalysis of Cellular Encryption (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 6 Oct 2026, 20:39 UTC

WeaknessesCWE-327

Technical details

References

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