Security readout for executives and security teams
Plain-English summary
A remote attacker may crash certain Open vSwitch deployments by sending an unusually long FTP EPASV command. The issue threatens availability, not data confidentiality or integrity. Exposure requires Open vSwitch to use FTP connection tracking helpers over the userspace datapath, so many installations may not be vulnerable in practice.
Executive priority
Treat this as a targeted availability risk rather than an enterprise-wide emergency. Promptly identify exposed network infrastructure because a successful attack could interrupt traffic processing. Accelerate remediation where FTP helper traffic is reachable from untrusted networks; otherwise handle through the normal vulnerability-management cycle while monitoring vendor guidance.
Technical view
CVE-2026-34956 is a CWE-120 heap access error triggered when an FTP EPASV command exceeds 255 characters. It affects the Open vSwitch FTP conntrack helper in the userspace datapath and can terminate the affected process or system service. CVSS 3.1 is 5.9, reflecting network reachability, high attack complexity, and high availability impact.
Likely exposure
Likely exposure is limited to Red Hat Fast Datapath for RHEL 7, 8, or 9 systems using listed Open vSwitch packages and configured with conntrack FTP helpers over the userspace datapath. The bundle provides no precise affected version ranges, so package presence alone does not confirm vulnerability.
Exploitation context
The crafted FTP stream can be delivered remotely without privileges or user interaction, but successful exploitation requires a specific configuration. The bundle does not identify public exploit code, observed attacks, or active exploitation, and the CVE is not listed as KEV.
Researcher notes
The source bundle attributes the flaw to malformed EPASV parsing and identifies a heap access error, but supplies no crash trace, affected upstream version boundary, fixed build, or patch details. Several listed packages may reflect Red Hat product-level status rather than independently vulnerable components. Validate exposure using configuration and vendor package guidance, not package names alone.
Mitigation direction
- Review Red Hat's CVE advisory and Bugzilla entry for supported updates or configuration mitigations.
- Prioritize externally reachable systems using userspace datapath FTP connection tracking.
- Restrict untrusted FTP traffic to potentially affected systems while awaiting vendor remediation guidance.
- Apply vendor-supported fixes when available, following normal change-control and availability testing.
Validation and detection
- Inventory listed Open vSwitch packages across Red Hat Fast Datapath deployments.
- Confirm whether each system uses the userspace datapath and enables FTP conntrack helpers.
- Review service logs and monitoring for unexplained Open vSwitch crashes or restarts.
- Compare installed package builds with Red Hat's current advisory status and remediation guidance.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-120: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupContainer behavior lookup
The affected technology mentions containers, so container-specific ATT&CK technique review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-34956 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 5.9 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H2.23.6redhatVulnerability scoring details
Base CVSS 3.1 score
5.9MediumVector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- Source timelineredhat
Reported to Red Hat.
- Source timelineredhat
Made public.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://access.redhat.com/security/cve/CVE-2026-34956CVE reference, redhat · vdb-entry, x_refsource_REDHAT
- RHBZ#2453459CVE reference, redhat · issue-tracking, x_refsource_REDHAT
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.