Which versions of BIG-IQ are affected by EUVD-2026-29957?

CVE-2026-20916 affects F5 BIG-IQ and allows authenticated users with low privileges to write arbitrary files to the system via path traversal, potentially enabling system compromise through…. A patch is available.

How to fix or mitigate EUVD-2026-29957?

Within 24 hours: Identify all F5 BIG-IQ instances in your environment and document current versions. Within 7 days: Apply F5's released patches to all supported BIG-IQ versions; verify patch installation and validate system functionality post-deployment. Within 30 days: Conduct access reviews to ensure low-privilege accounts have appropriate iControl REST endpoint restrictions and implement network segmentation to limit BIG-IQ administrative access.

BIG-IQ EUVD-2026-29957

Q: What is the CVSS score of EUVD-2026-29957?

EUVD-2026-29957 has a CVSS 4.0 base score of 7.2 (High). CVSS vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. EPSS exploitation probability: 0.1%.

| CVE-2026-20916 HIGH

Path Traversal (CWE-22)

2026-05-13 f5

GHSA-wph4-q4m8-f794

Path Traversal Big Iq F5

7.2

CVSS 4.0 · Vendor: f5

Severity by source

Vendor (f5) PRIMARY

7.2 HIGH

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Primary rating from Vendor (f5) · only source for this CVE.

CVSS VectorVendor: f5

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Lifecycle Timeline

Re-analysis Queued

May 13, 2026 - 16:22 vuln.today

cvss_changed

CVSS changed

May 13, 2026 - 16:22 NVD

8.1 (HIGH) 7.2 (HIGH)

Analysis Generated

May 13, 2026 - 15:45 vuln.today

CVE Published

May 13, 2026 - 14:12 nvd

HIGH 8.1

DescriptionCVE.org

An authenticated iControl REST user with low privileges can create or modify arbitrary files through an undisclosed iControl REST endpoint on the BIG-IQ system. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

AnalysisAI

Authenticated low-privilege users can write arbitrary files to the BIG-IQ system filesystem via path traversal in an undisclosed iControl REST endpoint, enabling system compromise through configuration manipulation or code execution. F5 has released patches for supported versions. While requiring authentication (PR:L), the low complexity (AC:L) and network vector (AV:N) allow remote attackers with minimal access to achieve high integrity and availability impact through file overwrites of critical system or application files.

Technical ContextAI

BIG-IQ is F5's centralized management platform for BIG-IP devices, using iControl REST API for programmatic configuration and monitoring. This vulnerability exploits CWE-22 (Path Traversal) in an undisclosed iControl REST endpoint, where insufficient input validation allows authenticated users to escape intended directory boundaries using relative path sequences (e.g., '../') in API requests. The iControl REST framework should restrict file operations to designated directories based on user privilege levels, but the vulnerable endpoint fails to properly sanitize file path parameters. This enables low-privilege users to write files outside their authorized scope, potentially overwriting system configuration files, startup scripts, or web application code to escalate privileges or achieve code execution.

RemediationAI

Apply vendor-supplied patches immediately per F5 Security Advisory K000158029 (https://my.f5.com/manage/s/article/K000158029), which provides version-specific upgrade paths for supported BIG-IQ releases. Until patching is complete, implement network-level access controls restricting iControl REST API access to trusted administrative hosts only (not general network access), enforce least-privilege principles by auditing and removing unnecessary low-privilege API accounts, enable comprehensive API request logging to detect path traversal attempts (monitor for '../' sequences or absolute paths in file parameters), and review existing file integrity on BIG-IQ systems to identify any unauthorized modifications. Note that restricting API access may impact legitimate automation workflows and should be coordinated with application teams. If running an EoTS version, prioritize migration to a supported release as no patches will be issued for unsupported versions.