CVE-2026-49114

ONNX symlink-following and path-traversal arbitrary file write

HIGH
7.1
CVSS Score
Published: August 21, 2026 at 04:10 PM UTC
Updated: October 15, 2026 at 07:10 PM UTC
2 products affected across 2 vendorsOnnxONNX

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Severity
HIGH7.1
Exploit prediction
EPSS 0.2%
SSVC
PoC

Description

In ONNX before 1.21.0, the 'save_external_data' function builds the external-data file path from the model's external_data location field and opens it for writing without 'O_NOFOLLOW/O_EXCL', after a non-atomic 'os.path.isfile()' check. A local attacker with write access to the directory where a victim serializes external data can deterministically pre-plant a symlink that is being followed, causing the victim's write to append to any file the victim can write, e.g. ~/.ssh/authorized_keys, cron files, or application configs. Fixed in 1.21.0.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 1.21.0
Affected range stops below 1.21.0, so it looks safe — our inference, not a vendor statement
0 ≤ v < 1.21.0
Vendor states this is fixed in 1.21.0 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (3)

SSVC — Action Prioritization

SSVCPoCNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.1HIGHcisa-cg
Attack Vector
LOCAL
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
NONE
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-367CWE-22CWE-59

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