Raw vector
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:A/VC:H/VI:H/VA:H/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/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:XCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2025-43856 is a high-severity Incorrect Implementation of Authentication Algorithm (CWE-303) vulnerability. Its CVSS base score is 7.3 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique External Remote Services (T1133); ranked at the 26th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SA-15 (Development Process, Standards, and Tools) — see the control section below for these in your framework.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-21169
Vulnerability Data
immich is a high performance self-hosted photo and video management solution. Prior to 1.132.0, immich is vulnerable to account hijacking through oauth2, because the state parameter is not being checked. The oauth2 state parameter is similar to a csrf token,…
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so when the user starts the login flow this unpredictable token is generated and somehow saved in the browser session and passed to the identity provider, which will return the state parameter when redirecting the user back to immich. Before the user is logged in that parameter needs to be verified to make sure the login was actively initiated by the user in this browser session. On it's own, this wouldn't be too bad, but when immich uses the /user-settings page as a redirect_uri, it will automatically link the accounts if the user was already logged in. This means that if someone has an immich instance with a public oauth provider (like google), an attacker can - for example - embed a hidden iframe in a webpage or even just send the victim a forged oauth login url with a code that logs the victim into the attackers oauth account and redirects back to immich and links the accounts. After this, the attacker can log into the victims account using their own oauth credentials. This vulnerability is fixed in 1.132.0.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Developer testing and evaluation at post-design stages directly uncovers incorrect implementations of required authentication algorithms.
Requiring documented development processes, standards, and tools reduces the chance that an established authentication algorithm is coded incorrectly.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly require correct implementation of authentication algorithms.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Secure authentication control directly requires correct implementation of authentication algorithms.
Security testing can detect flawed authentication implementations but does not prevent them by itself.
Cryptography control addresses proper use of authentication algorithms but is broader than authentication alone.
Secure development lifecycle includes verification steps that can catch incorrect authentication implementations.
Application security requirements can specify correct authentication algorithm use but do not guarantee correct implementation.
Secure coding practices reduce the likelihood of incorrect authentication algorithm implementation.