CVE-2026-102893
Zulip is an open-source team collaboration tool.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.39%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
Zulip is an open-source team collaboration tool. In Zulip Server versions through 12.1, GenericOpenIdConnectBackend matches the identity provider email claim to an active account's delivery_email without rejecting an explicitly false email_verified claim. If a configured identity provider returns an email address that the authenticating user does not control together with email_verified=false, Zulip can log the user into the existing account for that address. Exploitation requires a misconfigured trusted identity provider, and deployments whose authoritative identity provider only emits email addresses controlled by the authenticating user are not affected. This issue is fixed in version 12.2.
- CVSS 4.0
- 9.1 CRITICALCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
- EPSS
- 0.39% probability · 33th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-287
- Source
- security-advisories@github.com
EPSS moved from 0.4% on 15 October 2026 to 0.4% on 26 October 2026.
References
- https://github.com/zulip/zulip/commit/68d2d9defa39f8af96a50fc7430efc34dee120b5
- https://github.com/zulip/zulip/commit/b40f191a8c71e74fcb471f71de6a1233de157102
- https://github.com/zulip/zulip/pull/39913
- https://github.com/zulip/zulip/releases/tag/12.2
- https://github.com/zulip/zulip/security/advisories/GHSA-xw9h-9rcm-hx4m
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.