Evidence used
- No CISA KEV confirmation is currently recorded.
- The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
- EPSS is 0.53% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2026
CVE-2025-68775High confidence
net/handshake: duplicate handshake cancellations leak socket
Linux · Linux
9.8CriticalCVSS 3.1
Patch only the product branches with a verified fix
Fix availability varies by productCritical technical impact with a remotely reachable, unauthenticated path; no CISA KEV confirmation is currently recorded. Verified remediation exists for at least one product or source, but 204 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityCritical→Operational priority:Critical, 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 Linux Linux 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.
Remediation availability differs by product scope
Verified remediation exists for at least one product or source, but 204 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
- Red Hat Product Security: 184 affected or under-investigation product states without a fixed product state in the same current advisory
- Canonical Ubuntu Security: 20 affected package states with no published fix
Distribution package intelligence
24 package statesRelease-specific package status
Debian, ubuntu findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.
Package result overrides the generic status
BlackTree has verified remediation for at least one product or source, but the relevant distribution still reports no fixed package for 20 affected package states shown here. Treat those rows as affected with no fix until that distribution publishes a fixed version.
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 trixietrixie · source | linux | Vendor fix publishedDebian records a fixed source-package version for this release. | 6.12.69-1 | Debian Security Tracker ↗Source updated 5 Oct 2026 |
| Debian bookwormbookworm · source | linux | Not affectedDebian marks this release not affected (fixed-version marker 0). | Not published in this feed | Debian Security Tracker ↗Source updated 5 Oct 2026 |
| Debian forkyforky · source | linux | Vendor fix publishedDebian records a fixed source-package version for this release. | 6.18.3-1 | Debian Security Tracker ↗Source updated 5 Oct 2026 |
| Debian sidsid · source | linux | Vendor fix publishedDebian records a fixed source-package version for this release. | 6.18.3-1 | Debian Security Tracker ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-aws | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-azure | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-azure-fde | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-azure-nvidia | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-gcp | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-gke | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-gkeop | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-ibm | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-lowlatency | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-nvidia | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-nvidia-lowlatency | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-nvidia-tegra | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-oem-6.11 | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-oracle | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-raspi | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-raspi-realtime | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-realtime | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-riscv | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-xilinx | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 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-2025-68775 · CSAF 2.0 · revision 3 · finalRed Hat Product Securitykernel: net/handshake: duplicate handshake cancellations leak socket
The vendor explicitly identifies these products as affected by this CVE.
- kernel as a component of Red Hat Enterprise Linux 10
- kernel-64k as a component of Red Hat Enterprise Linux 10
- kernel-64k-core as a component of Red Hat Enterprise Linux 10
- kernel-64k-debug as a component of Red Hat Enterprise Linux 10
- kernel-64k-debug-core as a component of Red Hat Enterprise Linux 10
- kernel-64k-debug-devel as a component of Red Hat Enterprise Linux 10
- kernel-64k-debug-devel-matched as a component of Red Hat Enterprise Linux 10
- kernel-64k-debug-modules as a component of Red Hat Enterprise Linux 10
- kernel-64k-debug-modules-core as a component of Red Hat Enterprise Linux 10
- kernel-64k-debug-modules-extra as a component of Red Hat Enterprise Linux 10
- kernel-64k-devel as a component of Red Hat Enterprise Linux 10
- kernel-64k-devel-matched as a component of Red Hat Enterprise Linux 10
- Summary
- A race condition flaw was found in the Linux kernel's network handshake subsystem. When duplicate handshake cancellation requests arrive for the same TLS handshake (such as during SUNRPC/NFS TLS negotiation timeouts), the code fails to detect the duplicate and incorrectly manipulates the socket reference count, leading to a refcount underflow and potential socket resource leak.
- Remediation
- Fix deferred
Critical technical impact with a remotely reachable, unauthenticated path; no CISA KEV confirmation is currently recorded. Verified remediation exists for at least one product or source, but 204 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
Fix availability varies by product01
What, why and how
In the Linux kernel, the following vulnerability has been resolved: net/handshake: duplicate handshake cancellations leak socket When a handshake request is cancelled it is removed from the handshake_net->hn_requests list, but it is still present in the handshake_rhashtbl until it is destroyed. If a second cancellation request arrives for the same handshake request, then remove_pending() will return false... and assuming HANDSHAKE_F_REQ_COMPLETED isn't set in req->hr_flags, we'll continue processing through the out_true label, where we put another reference on the sock and a refcount underflow occurs. This can happen for example if a handshake times out - particularly if the SUNRPC client sends the AUTH_TLS probe to the server but doesn't follow it up with the ClientHello due to a problem with tlshd. When the timeout is hit on the server, the server will send a FIN, which triggers a cancellation request via xs_reset_transport(). When the timeout is hit on the client, another cancellation request happens via xs_tls_handshake_sync(). Add a test_and_set_bit(HANDSHAKE_F_REQ_COMPLETED) in the pending cancel path so duplicate cancels can be detected.
What
In the Linux kernel, the following vulnerability has been resolved: net/handshake: duplicate handshake cancellations leak socket When a handshake request is cancelled it is removed from the handshake_net->hn_requests list, but it is still present in the handshake_rhashtbl until it is destroyed. If a second cancellation request arrives for the same handshake request, then remove_pending() will return false... and assuming HANDSHAKE_F_REQ_COMPLETED isn't set in req->hr_flags, we'll continue processing through the out_true label, where we put another reference on the sock and a refcount underflow occurs. This can happen for example if a handshake times out - particularly if the SUNRPC client sends the AUTH_TLS probe to the server but doesn't follow it up with the ClientHello due to a problem with tlshd. When the timeout is hit on the server, the server will send a FIN, which triggers a cancellation request via xs_reset_transport(). When the timeout is hit on the client, another cancellation request happens via xs_tls_handshake_sync(). Add a test_and_set_bit(HANDSHAKE_F_REQ_COMPLETED) in the pending cancel path so duplicate cancels can be detected.
Why
The current structured CVE record identifies a security weakness, but the root cause requires confirmation in the linked vendor material.
How
An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
What
In the Linux kernel, the following vulnerability has been resolved: net/handshake: duplicate handshake cancellations leak socket When a handshake request is cancelled it is removed from the handshake_net->hn_requests list, but it is still present in the handshake_rhashtbl until it is destroyed. If a second cancellation request arrives for the same handshake request, then remove_pending() will return false... and assuming HANDSHAKE_F_REQ_COMPLETED isn't set in req->hr_flags, we'll continue processing through the out_true label, where we put another reference on the sock and a refcount underflow occurs. This can happen for example if a handshake times out - particularly if the SUNRPC client sends the AUTH_TLS probe to the server but doesn't follow it up with the ClientHello due to a problem with tlshd. When the timeout is hit on the server, the server will send a FIN, which triggers a cancellation request via xs_reset_transport(). When the timeout is hit on the client, another cancellation request happens via xs_tls_handshake_sync(). Add a test_and_set_bit(HANDSHAKE_F_REQ_COMPLETED) in the pending cancel path so duplicate cancels can be detected.
Why
The current structured CVE record identifies a security weakness, but the root cause requires confirmation in the linked vendor material.
How
An attacker operating through a network path may attempt exploitation without authentication or user interaction. 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 → vulnerable operation → cause the confidentiality, integrity or availability impact described by the vendor
- Attack surface
- Network
- Privileges required
- None: unauthenticated exploitation is possible
- 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. - CWE not yet assigned
- 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:N/UI:N/S:U/C:H/I:H/A:HCommon 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.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.AHighAvailability impact: A successful attack can cause a major loss.- 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. - Fix availability varies by product
- Affected
- kernel as a component of Red Hat Enterprise Linux 10
- kernel-64k as a component of Red Hat Enterprise Linux 10
- kernel-64k-core as a component of Red Hat Enterprise Linux 10
- kernel-64k-debug as a component of Red Hat Enterprise Linux 10
- kernel-64k-debug-core as a component of Red Hat Enterprise Linux 10
- kernel-64k-debug-devel as a component of Red Hat Enterprise Linux 10
- kernel-64k-debug-devel-matched as a component of Red Hat Enterprise Linux 10
- kernel-64k-debug-modules as a component of Red Hat Enterprise Linux 10
- kernel-64k-debug-modules-core as a component of Red Hat Enterprise Linux 10
- kernel-64k-debug-modules-extra as a component of Red Hat Enterprise Linux 10
- kernel-64k-devel as a component of Red Hat Enterprise Linux 10
- kernel-64k-devel-matched as a component of Red Hat Enterprise Linux 10
- kernel-64k-modules as a component of Red Hat Enterprise Linux 10
- kernel-64k-modules-core as a component of Red Hat Enterprise Linux 10
- kernel-64k-modules-extra as a component of Red Hat Enterprise Linux 10
- kernel-abi-stablelists as a component of Red Hat Enterprise Linux 10
- kernel-core as a component of Red Hat Enterprise Linux 10
- kernel-debug as a component of Red Hat Enterprise Linux 10
- kernel-debug-core as a component of Red Hat Enterprise Linux 10
- kernel-debug-devel as a component of Red Hat Enterprise Linux 10
- kernel-debug-devel-matched as a component of Red Hat Enterprise Linux 10
- kernel-debug-modules as a component of Red Hat Enterprise Linux 10
- kernel-debug-modules-core as a component of Red Hat Enterprise Linux 10
- kernel-debug-modules-extra as a component of Red Hat Enterprise Linux 10
- kernel-debug-uki-virt as a component of Red Hat Enterprise Linux 10
- kernel-devel as a component of Red Hat Enterprise Linux 10
- kernel-devel-matched as a component of Red Hat Enterprise Linux 10
- kernel-doc as a component of Red Hat Enterprise Linux 10
- kernel-modules as a component of Red Hat Enterprise Linux 10
- kernel-modules-core as a component of Red Hat Enterprise Linux 10
- and 154 more
- Action
- Use the product-specific evidence above. Patch only products with a verified fixed release, and keep every affected or under-investigation state without a matching fix in the remediation queue.
- 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 13 Jan 2026 · Last source change 5 Aug 2026, 12:11 UTC · CWE not yet assigned
CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source FIRST · tracked since 2026-08-14
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2026-2318
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceUnavailable
NVD statusNVD not scheduled
Missing structured fields: CWE classification. Missing data is not evidence of low risk; review the primary advisory.
Material change intelligence
View recent updates ↗What changed after publication
No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.
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.