CVE-2026-66884Public exploitNetwork attack vector

Forced login via fail-open callback validation

Published Aug 4, 2026 · Updated Aug 4, 2026

CSRF in Erlang Ecosystem Foundation oidcc_plug 0.2.0-beta.1 through 0.4.9 allows remote attackers to force an uninitiated login flow. Oidcc.Plug.AuthorizationCallback.call/2 substitutes permissive defaults when its authorize session is absent, causing nonce, state, PKCE, peer-IP, and user-agent checks to return success. Exploitation requires active victim interaction and a provider that does not enforce PKCE; it signs the victim into the attacker's account, while shared sign-in and linking callbacks expose account takeover.

CVSS severity2.1
Low
EPSS probability0.21%
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

CSRF in Erlang Ecosystem Foundation oidcc_plug 0.2.0-beta.1 through 0.4.9 allows remote attackers to force an uninitiated login flow. Oidcc.Plug.AuthorizationCallback.call/2 substitutes permissive defaults when its authorize session is absent, causing nonce, state, PKCE, peer-IP, and user-agent checks to return success. Exploitation requires active victim interaction and a provider that does not enforce PKCE; it signs the victim into the attacker's account, while shared sign-in and linking callbacks expose account takeover.

The record

CVE
CVE-2026-66884
Published
Aug 4, 2026
Updated
Aug 4, 2026
Vendor
Erlang Ecosystem Foundation
Product
oidcc_plug
Classifications
CWE-352, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 4, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2026Record 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=0.2.0-beta.1 <0.5.0
  2. Affected versionversion=e577ae73b9080693442916043a22d8f05491dd93 <97d75afc57826dca31989b47d6e2a3c136039917

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Erlang Ecosystem Foundation · oidcc_plugversion=0.2.0-beta.1 <0.5.0; version=e577ae73b9080693442916043a22d8f05491dd93 <97d75afc57826dca31989b47d6e2a3c136039917

Published CVSS scores

2.1Erlang Ecosystem FoundationCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA: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 exploitPublished

Weakness, pattern, technique

CWE-352Cross-Site Request Forgery (CSRF)
T1204.001User Execution: Malicious Link

Public exploit references

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