by Kastro
Paper/Archive/CVE-2026-87802

CVE-2026-87802

Apache Software Foundation Apache Syncope — Apache Syncope: SRA OAuth2 JWT signature verification bypass

EPSS 0.3%CVSS 9.1
critical.is priorityof 100
31
CVSS 9.1 (ADP)9.1 / 10 × 3027.3Not in CISA KEV+300.0EPSS percentile 20.1.201 × 204.0No public exploit+100.0SSVC exploitation: none+100.0
Description · from the CVE record

Improper verification of cryptographic signature vulnerability in Apache Syncope. When SRA is configured for OAuth 2.0 without JWKS set URI assigned, an attacker can forge arbitrary JWTs to impersonate any user identity and permissions, gaining full access to services proxied by SRA. This issue affects Apache Syncope: from 3.0.0-M0 through 3.0.16, from 4.0.0-M0 through 4.0.7, from 4.1.0-M0 through 4.1.2. Users are recommended to upgrade to version 4.0.8 / 4.1.3, which fix this issue.

Affected

ProductAffectedFixed inSource
Apache Syncope3.0.0-M0 – 3.0.16–CNA
Apache Syncope4.0.0-M0 – 4.0.7–CNA
Apache Syncope4.1.0-M0 – 4.1.2–CNA

Scores by source

CISA ADP9.1CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CISA ADPSSVCExploitation: none · Automatable: yes · Technical impact: total

References

advisorylists.apache.org/thread/gx83cootj00kn8hqd73x1bp8441np33drefopenwall.com/lists/oss-security/2026/09/14/25