CyberSecBulletin
CVE-2026-42930NVD status: Undergoing Analysis

BIG-IP: Path Traversal: '.../...//'

Published Updated By the CyberSecBulletin desk

CVE-2026-42930 is a high-severity path traversal: '.../...//' vulnerability in BIG-IP from F5, with a CVSS 3.1 base score of 8.7 out of 10. It can be exploited remotely over the network by an attacker with administrator privileges, without any action from a user. The record lists versions 21.0.0.2, 17.5.1.6, 17.1.3.2 as the first without the flaw, so updating BIG-IP to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.48% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update BIG-IP to 21.0.0.2 or 17.5.1.6 or 17.1.3.2, whichever matches your release line, or a later version.
  2. Read the advisory on my.f5.com for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
F5BIG-IP21.0.0 up to, but not including, 21.0.0.2; 17.5.0 up to, but not including, 17.5.1.6; 17.1.0 up to, but not including, 17.1.3.2; 16.1.0 and later21.0.0.2, 17.5.1.6, 17.1.3.2
F5Big-ip Access Policy Manager21.0.0; 17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6Not stated
F5Big-ip Advanced Firewall Manager21.0.0; 17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6Not stated
F5Big-ip Advanced Web Application Firewall21.0.0; 17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6Not stated
F5Big-ip Analytics21.0.0; 17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6Not stated
F5Big-ip Application Acceleration Manager21.0.0; 17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6Not stated
F5Big-ip Application Security Manager21.0.0; 17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6Not stated
F5Big-ip Application Visibility And Reporting21.0.0; 17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6Not stated
F5Big-ip Automation Toolchain21.0.0; 17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6Not stated
F5Big-ip Carrier-grade Nat21.0.0; 17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6Not stated
F5Big-ip Container Ingress Services21.0.0; 17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6Not stated
F5Big-ip Ddos Hybrid Defender21.0.0; 17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6Not stated
F5Big-ip Domain Name System21.0.0; 17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6Not stated
F5Big-ip Edge Gateway21.0.0; 17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6Not stated
F5Big-ip Fraud Protection Service21.0.0; 17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6Not stated
F5Big-ip Global Traffic Manager21.0.0; 17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6Not stated
F5Big-ip Link Controller21.0.0; 17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6Not stated
F5Big-ip Local Traffic Manager21.0.0; 17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6Not stated
F5Big-ip Policy Enforcement Manager21.0.0; 17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6Not stated
F5Big-ip SSL Orchestrator21.0.0; 17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6Not stated
F5Big-ip Webaccelerator21.0.0; 17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6Not stated
F5Big-ip Websafe21.0.0; 17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6Not stated

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
HighAdministrator-level access is required first.
User interaction
NoneNo action by a victim is required.
Scope
ChangedThe attack can reach beyond the vulnerable component into other systems.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
NoneAvailability is not affected.

Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N. Scored by CNA (f5.com).

Scoring systemScoreSeverityScored by
CVSS 4.08.5HighCNA (f5.com)
CVSS 3.18.7HighCNA (f5.com)

Official description

When running in Appliance mode, an authenticated attacker assigned the 'Administrator' role may be able to bypass Appliance mode restrictions on a BIG-IP system. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Path Traversal: '.../...//'

The product uses external input to construct a pathname that should be within a restricted directory, but it does not properly neutralize '.../...//' (doubled triple dot slash) sequences that can resolve to a location that is outside of that directory.

How developers prevent this class of flaw

  • Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.

More Path Traversal: '.../...//' vulnerabilities (CWE-35)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in BIG-IP

All BIG-IP vulnerabilities

Recent Path Traversal: '.../...//' vulnerabilities

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