What is the CVSS score of CVE-2026-27812?

CVE-2026-27812 has a CVSS 3.1 base score of 9.1 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N. EPSS exploitation probability: 0.0%.

How to fix or mitigate CVE-2026-27812?

Within 24 hours: Isolate Sub2API instances from external networks if possible and disable password reset functionality until patched; notify all users to change passwords via secure out-of-band channels and monitor for unauthorized account access. Within 7 days: Implement WAF rules to block suspicious Host and Forwarded headers, conduct forensic analysis of password reset logs for exploitation evidence, and establish communication with the Sub2API vendor on patch timeline. Within 30 days: Deploy the patch immediately upon vendor release, conduct full account audit for unauthorized access, force password resets across all Sub2API users, and review API quota usage for anomalies.

Sub2api CVE-2026-27812

CRITICAL

Improper Encoding or Escaping of Output (CWE-116)

2026-02-26 security-advisories@github.com

XSS AI / ML Sub2api

9.1

CVSS 3.1 · GitHub Advisory

View

Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

Access

Send password reset request
Delivery

Inject malicious Host/Forwarded header
Exploit

Attacker domain embedded in reset link
Execution

User clicks poisoned link
Persist

Attacker captures credentials
Impact

Account takeover

Vulnerability Assessment

Weakness	CWE CWE-116 OWASP Top 10:2025 A05:2025 - Injection ASVS 5.0 V1 - Encoding and Sanitization Output encoding for downstream
Exploitation Conditions	Sub2API versions prior to 0.1.85 with 'forgot password' feature enabled. Server must trust Host or Forwarded HTTP headers without validation. No authentication required; exploitable against default configurations accepting unauthenticated password reset requests.
Impact	CVSS 9.1. AI API gateways process sensitive queries and responses between users and AI models.
Exploit ScenarioDerived	Attacker injects malicious content through the API that is improperly encoded in responses, affecting downstream consumers.

Act Now Prioritize within 24-48h. Why: CRITICAL severity.

No patch listed yet 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

Improper output encoding in Sub2API AI API gateway allows injection attacks. The platform distributes AI API quotas without properly encoding output.

Earlier versions of this analysis (1)

v1 Mar 12, 2026 - 21:55 CVSS 9.1

Output encoding vulnerability in Sub2API AI API gateway.

RemediationAI

Update Sub2API.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

CWE-116 improper encoding of output in the AI API gateway platform.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

GitHub Advisory PRIMARY 9.1 CRITICAL

AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

None

DescriptionGitHub Advisory

Sub2API is an AI API gateway platform designed to distribute and manage API quotas from AI product subscriptions. A vulnerability in versions prior to 0.1.85 is a Password Reset Poisoning (Host Header / Forwarded Header trust issue), which allows attackers to manipulate the password reset link. Attackers can exploit this flaw to inject their own domain into the password reset link, leading to the potential for account takeover. The vulnerability has been fixed in version v0.1.85. If upgrading is not immediately possible, users can mitigate the vulnerability by disabling the "forgot password" feature until an upgrade to a patched version can be performed. This will prevent attackers from exploiting the vulnerability via the affected endpoint.

Executive ViewAI

Why It Matters

Sub2API versions prior to 0.1.85 contain a critical password reset poisoning vulnerability that allows attackers to redirect users to malicious sites and capture credentials, potentially compromising all API quota management and subscription data. This affects any organization using Sub2API as their AI API gateway, with no available patch currently requiring immediate containment measures.

Business Impact: Severe

Compensating Controls

Implement WAF rules to validate and restrict Host and Forwarded header values to known legitimate domains; segment Sub2API network access to trusted internal networks only; disable or restrict password reset functionality until patched; enable multi-factor authentication (MFA) on all Sub2API accounts to prevent credential-based account takeover; monitor all password reset requests and login attempts for anomalies; implement reverse proxy with header sanitization between users and Sub2API.

Threat Intelligence Overview

EPSS Score

0.0%

Top 86% exploitable

Data Quality

4 sources

Confidence: Medium

NVD

CVE.org

EPSS

GitHub

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity CRITICAL

CISA KEV No

Public POC No

EPSS 0.0%

Patch available No

Active threat No

Deciding rule

CRITICAL severity

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.