Security readout for executives and security teams
Plain-English summary
CVE-2026-34963 affects the barebox bootloader before version 2026.04.0. A malicious EFI PE boot binary could corrupt memory while being loaded, potentially letting an attacker run code before the operating system starts. Risk is concentrated in devices or workflows that allow untrusted boot files from USB, SD, TFTP, or network boot.
Executive priority
Prioritize for embedded products and operational environments where attackers can influence boot media or provisioning infrastructure. This is not a broad enterprise desktop issue unless barebox is present, but affected devices may face pre-OS compromise risk.
Technical view
The issue is in barebox efi/loader/pe.c. Integer overflow during virtual image size calculation can cause undersized heap allocation, and section loading does not validate raw data bounds against the PE buffer. The reported impact is heap buffer overflow or out-of-bounds heap read, potentially leading to bootloader-context code execution.
Likely exposure
Exposure is likely limited to systems using barebox EFI PE loading, especially embedded devices, development boards, appliances, or provisioning flows that boot PE images from removable media, TFTP, SD card, USB, or network boot.
Exploitation context
The source bundle says exploitation requires supplying a malicious EFI PE binary through an accepted boot source. CVE KEV status is false, and the provided sources do not state active exploitation in the wild.
Researcher notes
Focus validation on version lineage and reachability of efi/loader/pe.c through supported boot flows. The bundle identifies CWE-190 and memory-safety impacts, but does not provide complete downstream affected product mapping.
Mitigation direction
- Upgrade barebox to v2026.04.0 or later where applicable.
- Check barebox vendor guidance and downstream device firmware advisories.
- Restrict untrusted USB, SD, TFTP, and network boot paths.
- Require trusted boot media in provisioning and recovery workflows.
- Review embedded product firmware update plans for barebox dependency exposure.
Validation and detection
- Inventory products and firmware builds that include barebox.
- Confirm whether affected builds use the EFI PE loader path.
- Verify barebox version is v2026.04.0 or later.
- Review boot configuration for TFTP, USB, SD, or network boot acceptance.
- Check downstream vendor firmware advisories for patched releases.
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-190: 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 lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-34963 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
- High
- CVSS
- 8.6 (4.0)
- Known Exploited
- No
- Published
Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
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
2 official scoresWe 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:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N——VulnCheckCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H2.55.9VulnCheckVulnerability scoring details
Base CVSS 4.0 score
8.6HighVector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Base CVSS 3.1 score
8.4HighVector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- 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://github.com/barebox/bareboxCVE reference, VulnCheck · product
- https://github.com/barebox/barebox/releases/tag/v2026.04.0CVE reference, VulnCheck · patch
- https://www.vulncheck.com/advisories/barebox-efi-pe-loader-memory-safety-vulnerabilitiesCVE reference, VulnCheck · third-party-advisory
- Blog PostCVE reference, VulnCheck · technical-description
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.
Integer Overflow or Wraparound
Integer Overflow or Wraparound represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.