CVE-2026-19349Network attack vector

Authentication bypass via misclassified OAuth2 state session

Published Aug 16, 2026 · Updated Aug 16, 2026

Authentication bypass in Lemonldap::NG::Portal before 2.16.9 allows remote attackers to obtain unauthenticated SSO sessions. GitHub and LinkedIn extractFormInfo() calls pass positional values to getApacheSession(), which treats them as named options, defaults kind to SSO, and stores OAuth2 state in global SSO storage. Only deployments enabling either backend are affected; replaying the issued state identifier as a cookie bypasses login when rules accept sessions without a user or authentication level.

CVSS severity9.8
Critical
EPSS probability0.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Lemonldap::NG::Portal before 2.16.9 allows remote attackers to obtain unauthenticated SSO sessions. GitHub and LinkedIn extractFormInfo() calls pass positional values to getApacheSession(), which treats them as named options, defaults kind to SSO, and stores OAuth2 state in global SSO storage. Only deployments enabling either backend are affected; replaying the issued state identifier as a cookie bypasses login when rules accept sessions without a user or authentication level.

The record

CVE
CVE-2026-19349
Published
Aug 16, 2026
Updated
Aug 16, 2026
Vendor
LemonLDAP::NG
Product
Lemonldap::NG::Portal
Classifications
CWE-305, CWE-628, T1550.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 16, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 16, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=2.0.0 <2.16.9
  2. Affected versionversion=2.17.0 <2.21.5
  3. Affected versionversion=2.22.0 <2.23.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

LemonLDAP::NG · Lemonldap::NG::Portalversion=2.0.0 <2.16.9; version=2.17.0 <2.21.5; version=2.22.0 <2.23.3

Published CVSS scores

9.8INCIBE-CERTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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

CWE-305Authentication Bypass by Primary Weakness
CWE-628Function Call with Incorrectly Specified Arguments
T1550.004Use Alternate Authentication Material: Web Session Cookie

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

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Your stack

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