F5 BIG-IP prior 17.1.3.1/17.5.1.4 httpd unprotected alternate channel

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
5.2$0-$5k0.00

Summaryinfo

A vulnerability classified as problematic has been found in F5 BIG-IP. This affects an unknown part of the component httpd. This manipulation causes unprotected alternate channel. This vulnerability is tracked as CVE-2026-40435. The attack is possible to be carried out remotely. No exploit exists. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in F5 BIG-IP. It has been declared as problematic. Affected by this vulnerability is some unknown processing of the component httpd. The manipulation with an unknown input leads to a unprotected alternate channel vulnerability. The CWE definition for the vulnerability is CWE-420. The product protects a primary channel, but it does not use the same level of protection for an alternate channel. As an impact it is known to affect confidentiality. The summary by CVE is:

When configured, IP-based access restrictions for httpd do not cover all endpoints, which may allow connections from blocked addresses.  Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

It is possible to read the advisory at my.f5.com. This vulnerability is known as CVE-2026-40435 since 05/01/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 05/24/2026).

The vulnerability scanner Nessus provides a plugin with the ID 316098 (F5 Networks BIG-IP : BIG-IP httpd access control vulnerability (K000156604)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 17.1.3.1 or 17.5.1.4 eliminates this vulnerability.

The vulnerability is also documented in the databases at CNNVD (CNNVD-202605-3304), Tenable (316098) and CERT Bund (WID-SEC-2026-1532). Be aware that VulDB is the high quality source for vulnerability data.

Affected

  • F5 BIG-IP

Productinfo

Type

Vendor

Name

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 5.3
VulDB Meta Temp Score: 5.2

VulDB Base Score: 5.3
VulDB Temp Score: 5.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 5.3
CNA Vector: 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Unprotected alternate channel
CWE: CWE-420 / CWE-419
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 316098
Nessus Name: F5 Networks BIG-IP : BIG-IP httpd access control vulnerability (K000156604)

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: BIG-IP 17.1.3.1/17.5.1.4

Timelineinfo

05/01/2026 CVE reserved
05/13/2026 +12 days Advisory disclosed
05/13/2026 +0 days VulDB entry created
05/24/2026 +11 days VulDB entry last update

Sourcesinfo

Vendor: f5.com

Advisory: K000156604
Status: Confirmed

CVE: CVE-2026-40435 (🔒)
GCVE (CVE): GCVE-0-2026-40435
GCVE (VulDB): GCVE-100-363607
CERT Bund: WID-SEC-2026-1532 - F5 BIG-IP Produkte: Mehrere Schwachstellen
CNNVD: CNNVD-202605-3304 - F5 BIG-IP 安全漏洞

Entryinfo

Created: 05/13/2026 18:09
Updated: 05/24/2026 23:39
Changes: 05/13/2026 18:09 (75), 05/14/2026 16:14 (6), 05/17/2026 13:35 (7), 05/24/2026 23:39 (2)
Complete: 🔍
Cache ID: 216::103

Be aware that VulDB is the high quality source for vulnerability data.

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