Security readout for executives and security teams
Plain-English summary
ONNX before 1.21.0 can be tricked through symlinks into reading files outside the intended model or user-provided directory. The main business risk is unintended disclosure of sensitive local files in systems that process untrusted ONNX content. The source bundle says this is patched in ONNX 1.21.0.
Executive priority
Prioritize remediation for internet-facing, partner-facing, or automated ML ingestion systems. This is mainly a confidentiality issue, but arbitrary local file reads can expose credentials, tokens, datasets, or configuration secrets if processing environments are overprivileged.
Technical view
This is a symlink-assisted path traversal/arbitrary file read in ONNX, mapped to CWE-22, CWE-23, and CWE-61. The listed CVSS 4.0 score is 8.7 High, with network attack vector, low complexity, no privileges, no user interaction, and high vulnerable-system confidentiality impact only.
Likely exposure
Highest exposure is in applications, services, notebooks, CI jobs, or ML pipelines running ONNX versions before 1.21.0 and processing ONNX model content from users, partners, repositories, or automated feeds. Exposure is lower where models are locally curated and isolated.
Exploitation context
The provided sources do not report active exploitation, and KEV is false. The vulnerability matters because untrusted model content may cause file reads outside expected directories. The bundle does not provide proof-of-concept details, exploit maturity, or affected downstream package status beyond ONNX before 1.21.0.
Researcher notes
Focus validation on symlink handling during ONNX file or directory processing, without expanding into weaponized reproduction. The public bundle names the fixed version and commit reference, but does not provide enough detail here to assert specific affected functions, downstream packages, or exploitation in the wild.
Mitigation direction
- Upgrade ONNX to version 1.21.0 or later.
- Check vendor or distribution advisories for packaged ONNX fixes.
- Avoid processing untrusted ONNX models until patched.
- Run model-processing workloads with minimal filesystem privileges.
- Restrict access to secrets from ML processing environments.
Validation and detection
- Inventory direct and transitive ONNX versions in applications and images.
- Confirm deployed ONNX is 1.21.0 or later.
- Identify services that accept externally supplied model files.
- Review filesystem access available to ONNX processing workloads.
- Track Red Hat and other vendor advisories for downstream status.
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-22: File access and web shell behavior lookup
File traversal and upload weaknesses can lead teams to review file, web shell, execution, and collection telemetry. 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 lookupCWE-23: File access and web shell behavior lookup
File traversal and upload weaknesses can lead teams to review file, web shell, execution, and collection telemetry. 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 lookupCWE-61: 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 lookupFile access behavior lookup
The CVE wording references file access or upload behavior, so file telemetry and web shell review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-27489 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
- 8.7 (4.0)
- Known Exploited
- No
- Published
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/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:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N——GitHub_MCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N3.94redhat-SADPVulnerability scoring details
Base CVSS 4.0 score
8.7HighVector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
Base CVSS 3.1 score
8.6HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
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.
- ADP timelineredhat-SADP
Made public.
- CVE publishedCVE Program
The CVE record was published.
- ADP timelineredhat-SADP
Reported to Red Hat.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
- 2026-04-01T18:01:42.208Z: Reported to Red Hat.
- 2026-04-01T17:33:51.281Z: Made public.
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/onnx/onnx/security/advisories/GHSA-3r9x-f23j-gc73CVE reference, GitHub_M · x_refsource_CONFIRM
- https://github.com/onnx/onnx/commit/4755f8053928dce18a61db8fec71b69c74f786cbCVE reference, GitHub_M · x_refsource_MISC
- https://access.redhat.com/security/cve/CVE-2026-27489CVE reference, redhat-SADP · vdb-entry, x_refsource_REDHAT
- RHBZ#2453929CVE reference, redhat-SADP · issue-tracking, x_refsource_REDHAT
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27489.jsonCVE reference, redhat-SADP · x_sadp-csaf-vex
- https://access.redhat.com/errata/RHSA-2026:24977CVE reference, redhat-SADP · vendor-advisory, 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.
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Relative Path Traversal
Relative Path Traversal represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
UNIX Symbolic Link (Symlink) Following
UNIX Symbolic Link (Symlink) Following represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.