Evidence used
- No CISA KEV confirmation is currently recorded.
- EPSS is 0.14% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2026
CVE-2026-102824High confidence
Russh: Missing X25519 zero-point validation in hybrid ML-KEM key exchange
Eugeny · russh
Official source article: GitHub GHSA-W3JG-PJXF-73P4 ↗. Check the applicable product and release in the original source.
4.3MediumCVSS 3.1
Scheduled
Patch availableMedium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityMedium→Operational priority:Medium, unchanged from published severity.unchanged
Compensating controls
- Validate the affected product branch and deploy the verified fixed release.
- Restrict the affected network interface to trusted sources where business-safe.
- Monitor vendor guidance and exploitation sources for a material change.
Verification
- Confirm that the asset runs Eugeny russh and falls inside the recorded affected range.
- Verify the installed build against the product-specific fixed version after deployment.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Distribution package intelligence
1 package stateRelease-specific package status
Debian findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.
Repository candidate not checked
A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.
| Distribution release | Source package | Vendor state | Fixed version | Evidence |
|---|---|---|---|---|
| Debian sidsid · source | rust-russh | Vendor fix publishedDebian records a fixed source-package version for this release. | 0.64.1-1 | Debian Security Tracker ↗Source updated 7 Oct 2026 |
Open-source package ranges1 source-attributed range
These OSV and GitHub advisory ranges apply only to the named package and ecosystem. A listed fixed version is not a universal product patch or proof that an update is installed.
| Ecosystem and package | Affected range | First fixed version | Evidence |
|---|---|---|---|
| rustrussh | < 0.63.0 | 0.63.0 | GitHub advisory ↗upstream repository advisory · 30 Sep 2026 |
Direct vendor intelligence
1 currentAuthoritative vendor CSAF and VEX advisories
Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.
CVE-2026-102824 · CSAF 2.0 · revision 3 · finalRed Hat Product Securityrussh: russh: Cryptographic fallback bypass via missing public key validation
The vendor explicitly identifies these products or versions as containing the fix.
- openshell-0:0.1.2-0.2.hum1@aarch64 as a component of Red Hat Hardened Images
- openshell-0:0.1.2-0.2.hum1@src as a component of Red Hat Hardened Images
- openshell-0:0.1.2-0.2.hum1@x86_64 as a component of Red Hat Hardened Images
- openshell-gateway-0:0.1.2-0.2.hum1@aarch64 as a component of Red Hat Hardened Images
- openshell-gateway-0:0.1.2-0.2.hum1@x86_64 as a component of Red Hat Hardened Images
- python3-openshell-0:0.1.2-0.2.hum1@aarch64 as a component of Red Hat Hardened Images
- python3-openshell-0:0.1.2-0.2.hum1@x86_64 as a component of Red Hat Hardened Images
- Summary
- A flaw was found in russh. The library fails to validate peer public keys during hybrid cryptographic key exchange, accepting an all-zero key. A remote attacker acting as a malicious Secure Shell (SSH) peer can exploit this flaw during connection negotiation to force the classical encryption component of the shared secret to zero. This causes the connection to rely entirely on post-quantum algorithms, undermining the intended fallback protection of the hybrid exchange and weakening session security.
- Remediation
- For details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.
Patch available01
What, why and how
Russh is a Rust SSH client and server library. Prior to 0.63.0, the hybrid ML-KEM 768 and X25519 implementation in russh/src/kex/hybrid_mlkem.rs accepts an all-zero 32-byte peer X25519 public key in both server_dh and compute_shared_secret, forcing the X25519 contribution to the combined shared secret to zero. A malicious SSH peer can therefore make the combined secret depend only on ML-KEM, defeating the hybrid exchange's intended fallback protection if ML-KEM is later weakened. This issue is fixed in version 0.63.0.
What
Russh is a Rust SSH client and server library. Prior to 0.63.0, the hybrid ML-KEM 768 and X25519 implementation in russh/src/kex/hybrid_mlkem.rs accepts an all-zero 32-byte peer X25519 public key in both server_dh and compute_shared_secret, forcing the X25519 contribution to the combined shared secret to zero. A malicious SSH peer can therefore make the combined secret depend only on ML-KEM, defeating the hybrid exchange's intended fallback protection if ML-KEM is later weakened. This issue is fixed in version 0.63.0.
Why
The product uses a broken or risky cryptographic algorithm or protocol.
How
An attacker operating through a network path may attempt exploitation with low privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
What
Russh is a Rust SSH client and server library. Prior to 0.63.0, the hybrid ML-KEM 768 and X25519 implementation in russh/src/kex/hybrid_mlkem.rs accepts an all-zero 32-byte peer X25519 public key in both server_dh and compute_shared_secret, forcing the X25519 contribution to the combined shared secret to zero. A malicious SSH peer can therefore make the combined secret depend only on ML-KEM, defeating the hybrid exchange's intended fallback protection if ML-KEM is later weakened. This issue is fixed in version 0.63.0.
Why
The product uses a broken or risky cryptographic algorithm or protocol.
How
An attacker operating through a network path may attempt exploitation with low privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.
Public PoC / exploit material None recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.
- Likely attack path
- a network path → Use of a Broken or Risky Cryptographic Algorithm → cause the confidentiality, integrity or availability impact described by the vendor
- Attack surface
- Network
- Privileges required
- Low: a basic authenticated account is required
- User interaction
- None
- Attack complexity
- Low: no specialised conditions are recorded
- Security boundary
- Unchanged: impact remains within the vulnerable component's security authority
- Weakness
?
CWE means Common Weakness Enumeration: a standard category for the underlying weakness. - CWE-327 ↗
CWE-327: Use of a Broken or Risky Cryptographic Algorithm. The product uses a broken or risky cryptographic algorithm or protocol.
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:NCommon Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.
AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRLowPrivileges required: The attacker needs basic user-level privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CLowConfidentiality impact: A successful attack can cause a limited loss.INoneIntegrity impact: No direct loss is represented by this metric.ANoneAvailability impact: No direct loss is represented by this metric.- Post-exploitation / living off the land
- No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
03
Patch and workaround
Operational remediation based on structured source evidence.
- Status
?
Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change. - Patch available
- Affected
- russh: < 0.63.0
- Fixed
- openshell-0:0.1.2-0.2.hum1@aarch64 as a component of Red Hat Hardened Images
- openshell-0:0.1.2-0.2.hum1@src as a component of Red Hat Hardened Images
- openshell-0:0.1.2-0.2.hum1@x86_64 as a component of Red Hat Hardened Images
- openshell-gateway-0:0.1.2-0.2.hum1@aarch64 as a component of Red Hat Hardened Images
- openshell-gateway-0:0.1.2-0.2.hum1@x86_64 as a component of Red Hat Hardened Images
- python3-openshell-0:0.1.2-0.2.hum1@aarch64 as a component of Red Hat Hardened Images
- python3-openshell-0:0.1.2-0.2.hum1@x86_64 as a component of Red Hat Hardened Images
- Action
- For details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
- Workaround
- No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04
Evidence and provenance
Published 29 Sept 2026 · Last source change 30 Sept 2026, 20:24 UTC · CWE-327 · Use of a Broken or Risky Cryptographic Algorithm
CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source FIRST · tracked since 2026-09-30
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2026-89207
Product sourceCNA
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD not scheduled
Core structured fields are present and their contributing authorities are shown above.
Material change intelligence
View recent updates ↗What changed after publication
- Vendor guidanceAuthoritative vendor guidance changed from remediation: access.redhat.com/CVE-2026-102824 to remediation: access.redhat.com/CVE-2026-102824.Red Hat Product Security ↗
- Before
- remediation: access.redhat.com/CVE-2026-102824
- After
- remediation: access.redhat.com/CVE-2026-102824
- Remediation statusRemediation status changed from Awaiting fix to Patch available.Red Hat Product Security ↗
- Before
- Awaiting fix
- After
- Patch available
- Affected versionsThe structured affected or fixed version information changed.Red Hat Product Security ↗
- Before
- openshell.src as a component of Red Hat Hardened Images
- After
- Fixed: openshell-0:0.1.2-0.2.hum1@aarch64 as a component of Red Hat Hardened Images; openshell-0:0.1.2-0.2.hum1@src as a component of Red Hat Hardened Images; openshell-0:0.1.2-0.2.hum1@x86_64 as a component of Red Hat Hardened Images; openshell-gateway-0:0.1.2-0.2.hum1@aarch64 as a component of Red Hat Hardened Images; openshell-gateway-0:0.1.2-0.2.hum1@x86_64 as a component of Red Hat Hardened Images; python3-openshell-0:0.1.2-0.2.hum1@aarch64 as a component of Red Hat Hardened Images; python3-openshell-0:0.1.2-0.2.hum1@x86_64 as a component of Red Hat Hardened Images
- ENISA EUVD mappingEUVD-2026-89207 was added to the official ENISA EUVD mapping for this CVE.ENISA EUVD ↗
- Before
- not recorded
- After
- {"euvdId":"EUVD-2026-89207"}
- Catalogue recordCVE added to the BlackTree catalogue.CNA ↗
CVE published
Fixed release or patch reference recorded
Technical terms and abbreviations used in this report
- CVE
- Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
- CVSS
- Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
- EPSS
- Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
- CWE
- Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
- CNA
- CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
- CISA ADP
- Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
- NVD
- National Vulnerability Database: NIST's enrichment service for CVE records.
- CERT / CSIRT
- A computer security incident response team that publishes warnings or coordinates incident response.
- PoC
- Proof of concept: public material that demonstrates or helps reproduce exploitation.
- CSAF
- Common Security Advisory Framework: a machine-readable format for security advisories.
- LoTL
- Living off the land: abuse of legitimate tools or system functions during an attack.