CVE-2026-56223
CRITICAL 9.3 PoC AVAILABLECapgo before 12.128.2 contains a cross-domain SSO account takeover vulnerability in the provision-user endpoint that allows attackers to merge arbitrary victim accounts based on email match without validating SSO provider domain authorization. An attacker with enterprise org admin access and a malicious IdP can forge SAML assertions containing victim email addresses to trigger account merge and gain full access to victim accounts, organizations, and data.
Public exploit or PoC code exists. Modeled probability is still low, but the barrier to attack is reduced — watch closely.
Exploitation likelihood
0.2%chance of exploitation in 30 days · 16th percentile
Impact if exploited
9.3CVSS 4.0 · CRITICAL
- ConfidentialityHigh
- IntegrityHigh
- AvailabilityNone
What an attacker needs
- ✓Access: Reachable over the network — no local access needed
- ⚠Privileges: Requires an admin / high-privilege account
- ✓User interaction: No user interaction needed
- ✓Complexity: No special conditions — reliably repeatable
- ✓Requirements: No special attack requirements
✓ lowers the bar for an attacker · ⚠ raises it
Proof of concept & exploit code
- reference https://github.com/Cap-go/capgo/security/advisories/GHSA-jhjh-vp9p-54fg
- github-search Search GitHub for public PoC repos
Test against your own equipment
curl -s https://vulnpedia.com/cve/CVE-2026-56223/poc.jsonMachine-readable PoC index for this CVE (for automation).Listed for defensive triage, patch verification, and authorized testing on systems you own. Machine-readable: /cve/CVE-2026-56223/poc.json
Weakness (CWE)
- CWE-287: Improper Authentication
CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N
All CVSS metrics
- CRITICAL 9.3 v4.0 · CNA Primary
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N - HIGH 8.7 v3.1 · CNA Primary
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N - CRITICAL 9.3 v4.0 · NVD Secondary
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:N/SC:H/SI:H/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 - HIGH 8.7 v3.1 · NVD Secondary
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N