CVE-2026-119559

MEDIUM CVSS 5.9

Published: 2026-10-30

Modified: 2026-10-30

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AI Threat Summary

CVE-2026-119559 is a moderate vulnerability with a CVSS score of 5.9 affecting the target software. Authentication can be bypassed allowing unauthenticated access. Threat hunters should monitor for exploit attempts and apply vendor patches immediately.

Description

OpenLiteSpeed through 1.9.4 contains an authentication bypass vulnerability that allows unauthenticated remote attackers to evade virtual host client certificate requirements over HTTP/3. Because QuicStream inherits a verifyContext() implementation that always returns true, attackers can present a non-mTLS host's SNI with a protected Host header to access protected content.

Attack Chain

Reconnaissance

Attacker identifies authentication endpoint and tests for bypass conditions

Initial Access

Attacker exploits CVE-2026-119559 authentication flaw to gain unauthorized access without valid credentials

Discovery

Attacker enumerates accessible resources, users, and configurations

Collection

Attacker exfiltrates sensitive data accessible without proper authorization

MITRE ATT&CK Techniques

T1078 Valid Accounts

Initial Access

Authentication bypass grants attacker access as legitimate user

T1548 Abuse Elevation Control Mechanism

Privilege Escalation

Bypassed auth may grant elevated or admin-level permissions

Indicators of Compromise

Type	Value	Description
user_agent	`Mozilla/5.0 (compatible; exploit/1.0)`	Generic exploit scanner user agent pattern
url	`/api/vuln-endpoint?payload=<malicious>`	Exploit attempt against application endpoint — monitor access logs for anomalous params

Remediation

1. Apply vendor-supplied security patches immediately. 2. If patches are unavailable, apply recommended mitigations from the vendor advisory. 3. Enable WAF rules or IDS signatures to detect exploitation attempts. 4. Monitor logs for indicators of compromise listed above. 5. Implement network segmentation to limit blast radius if exploitation occurs. 6. Subscribe to vendor security advisories for this product.

Quick Facts

CVE ID	CVE-2026-119559
CVSS Score	5.9
Vector	`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N`
Published	2026-10-30
Exploited	No
CISA KEV	No
PoC	Not public

References

External Resources

NVD Entry BleepingComputer The Hacker News