OpenAM before 16.1.4 SAML 1.x Signature Verification Issuer Impersonation
Only affects OpenAM up to and including 16.1.3 when SAML 1.x is used with more than one trusted partner or with other parties' certificates in the keystore. Fixed in 16.1.4.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 16.1.4
- Who is exposed
- Specific setups only
Do first: Check whether your setup matches what the bug needs. Deployment uses SAML 1.x with more than one trusted partner, or keeps certificates of other parties in OpenAM's keystore OpenAM release up to and including 16.1.3
- Published
- Last modified
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 16/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
OpenAM before 16.1.4 does not verify that a signed SAML 1.x assertion or response was signed by the partner named as its issuer, accepting a signature from any certificate in OpenAM's keystore. An attacker holding such a private key, such as a trusted SAML 1.x partner, can forge assertions claiming another partner's issuer and sign in as that partner's users, including privileged ones.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure8/25Specific setups only, reachable over the network
- Reach?/20Unknown. No tracked technology or package matched
- Severity7.5/10CVSS 7.5
- No patch0/5No signal
What would change the score
- Would score about 66 if added to CISA KEV
- Would score about 61 if CISA's SSVC rates exploitation active
- Would score about 23 if CISA's SSVC rates it automatable
What to do
Check whether your setup matches what the bug needs.
Deployment uses SAML 1.x with more than one trusted partner, or keeps certificates of other parties in OpenAM's keystore OpenAM release up to and including 16.1.3Upgrade to a fixed version: 16.1.4.
Workaround: Remove SAML 1.x trusted partners and block the SAML 1.x endpoints at the reverse proxy if SAML 1.x is not in use
Timeline
- CVE published
- First seen by cve.now
Affected versions
- OpenIdentityPlatform OpenAM
fixed in 16.1.4
Evidence 2
- Advisory
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-123538
Is CVE-2026-123538 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
A holder of a trusted partner certificate's private key can sign SAML 1.x assertions that claim to come from a different partner. This lets the attacker sign in as that partner's users, including privileged ones.Source: github.com
Which versions are affected by CVE-2026-123538?
OpenAM: before 16.1.4.Source: cve.now feed data
Am I affected, and how do I check?
All OpenAM releases up to and including 16.1.3 are in scope, but only deployments that use SAML 1.x with more than one trusted partner or that keep other parties' certificates in OpenAM's keystore are affected. To check, confirm the installed release version and review the SAML 1.x trusted partner setup and keystore contents.Source: github.com
How do I fix CVE-2026-123538?
Upgrade to OpenAM 16.1.4, which contains the fix.Source: github.com