CVE-2023-50714Network attack vector

OAuth account compromise via PKCE downgrade and replay

Published Dec 22, 2023 · Updated Nov 27, 2024

OAuth2 PKCE weakness in Yiisoft Yii 2 AuthClient Extension before 2.2.15 allows remote attackers to compromise accounts via crafted OAuth flows. The OAuth2::fetchAccessToken method reused the session authCodeVerifier and forwarded an empty verifier while PKCE remained enabled, permitting replay and downgrade paths. Exploitation requires PKCE to protect the OAuth callback and user interaction with an attacker-influenced authorization flow; account confidentiality and integrity can be lost without interrupting service.

CVSS severity6.8
Medium
EPSS probability0.49%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

OAuth2 PKCE weakness in Yiisoft Yii 2 AuthClient Extension before 2.2.15 allows remote attackers to compromise accounts via crafted OAuth flows. The OAuth2::fetchAccessToken method reused the session authCodeVerifier and forwarded an empty verifier while PKCE remained enabled, permitting replay and downgrade paths. Exploitation requires PKCE to protect the OAuth callback and user interaction with an attacker-influenced authorization flow; account confidentiality and integrity can be lost without interrupting service.

The record

CVE
CVE-2023-50714
Published
Dec 22, 2023
Updated
Nov 27, 2024
Vendor
Yiisoft
Product
Yii 2 AuthClient Extension
Classifications
T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 22, 2023CVE publishedPublication date reported by the CVE source.
  2. Nov 27, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 2.2.15

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Yiisoft · Yii 2 AuthClient Extensionversion=< 2.2.15

Published CVSS scores

6.8GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo