Skip to content
Fencer Vulns
medium 6.8

CVE-2023-50714 json

The Oauth2 PKCE implementation is vulnerable

published 2023-12-18 2 y ago modified 2026-09-10 1 mo ago also GHSA-rw54-6826-c8j5 , EUVD-2023-3295

cvss
6.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 42%
public exploits
0
none known

Summary

yii2-authclient is an extension that adds OpenID, OAuth, OAuth2 and OpenId Connect consumers for the Yii framework 2.0. In yii2-authclient prior to version 2.2.15, the Oauth2 PKCE implementation is vulnerable in 2 ways. First, the `authCodeVerifier` should be removed after usage (similar to `authState`). Second, there is a risk for a `downgrade attack` if PKCE is being relied on for CSRF protection. Version 2.2.15 contains a patch for the issue. No known workarounds are available.

Patch / fix

  • packagist yiisoft/yii2-authclient 2.2.15
  • yiiframework yii2-authclient 2.2.15

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
23 mo ago

Exploit prediction

0.49% chance of exploitation in the next 30 days, higher than 42% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/yiisoft/yii2-authclient/security/advisories/GHSA-rw54-6826-c8j5 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 6.8 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N
NVD 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
GitHub 3.1 6.8 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N

Affected packages

ecosystem package affected fixed in
packagist yiisoft/yii2-authclient
<2.2.15
2.2.15

Affected products

  • yiisoft yii2-authclient

Classification

Weakness
  • CWE-918 Server-Side Request Forgery
  • CWE-347 Improper Verification of Cryptographic Signature
  • CWE-287 Improper Authentication

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.