CVE-2026-123540: Improper Encoding (CVSS 2)

Description

OpenAM before 16.1.4 contains an incomplete output encoding vulnerability that allows a SAML 1.x identity provider to alter attribute values by injecting unencoded content into the service provider auto-submitted form. Attackers controlling a trusted identity provider can craft assertion attribute names or values that reach the target application in modified form, undermining the integrity of received attributes.

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CVSS v3.1 Score

2.0

LOW

CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:L/A:N

EPSS — Exploit Prediction

0.0018

Probability of exploitation

0.08%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-116 CWE-116

References

Other References

https://github.com/OpenIdentityPlatform/OpenAM/security/advisories/GHSA-pw99-8h4m-p3gm https://www.vulncheck.com/advisories/openam-before-16.1.4-incomplete-attribute-encoding-in-saml-1-x-form-post

Frequently Asked Questions

What is CVE-2026-123540? +

OpenAM before 16.1.4 contains an incomplete output encoding vulnerability that allows a SAML 1.x identity provider to alter attribute values by injecting unencoded content into the service provider auto-submitted form. Attackers controlling a trusted identity provider can craft assertion attribute names or values that reach the target application in modified form, undermining the integrity of received attributes. It has a CVSS v3.1 base score of 2.0 (LOW).

How severe is CVE-2026-123540? +

CVE-2026-123540 has a CVSS v3.1 score of 2.0 out of 10, rated LOW. This is a low-severity vulnerability with limited impact. The EPSS score is 0.0018, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-123540? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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