CVE-2026-49197 Overview
CVE-2026-49197 is an authentication bypass vulnerability affecting web endpoints used by the Acer Connect application. The flaw stems from improper validation of the HTTP Authorization header. When Base64 decoding of the supplied credentials fails, the endpoints do not block the request and instead allow processing to continue. This logic gap permits unauthenticated network-based access to functionality intended to require valid credentials. The weakness is categorized under [CWE-287] Improper Authentication.
Critical Impact
An unauthenticated remote attacker can bypass authentication on Acer Connect web endpoints by sending a malformed Authorization header, gaining access to protected functions and data.
Affected Products
- Acer Connect application web endpoints
Discovery Timeline
- 2026-05-29 - CVE-2026-49197 published to NVD
- 2026-05-29 - Last updated in NVD database
Technical Details for CVE-2026-49197
Vulnerability Analysis
The vulnerability resides in how Acer Connect web endpoints process the HTTP Authorization header. HTTP Basic Authentication transmits credentials as a Base64-encoded string in the format Authorization: Basic <base64(username:password)>. The endpoints attempt to Base64-decode this header to extract and validate credentials.
When the decode operation fails because the supplied value is malformed, missing padding, or contains invalid characters, the endpoint logic does not return an authentication error. Instead, the request continues into protected handlers as if authentication had succeeded. This represents a classic fail-open authentication design, where an error condition in the credential parsing path bypasses the access control check entirely.
Root Cause
The root cause is missing negative-path handling in the authentication routine. The decoder result is consumed without verifying that decoding succeeded and that the resulting credentials matched a valid user. Any exception or null result from the Base64 decode step should terminate the request with an HTTP 401 response, but the affected code path does not enforce this control [CWE-287].
Attack Vector
An attacker reaches the vulnerable endpoint over the network without prior authentication or user interaction. The attacker sends an HTTP request to a protected Acer Connect endpoint and supplies an Authorization header containing a deliberately invalid Base64 payload. The server's decode attempt fails, the request is not rejected, and the protected handler executes. Because the attack requires no privileges and no interaction, it can be automated against any reachable instance. Refer to the Acer Knowledge Base Article for vendor-supplied technical context.
Detection Methods for CVE-2026-49197
Indicators of Compromise
- HTTP requests to Acer Connect endpoints carrying malformed Authorization: Basic headers, including values that are not valid Base64 or that contain illegal padding.
- Successful HTTP 200 responses from protected endpoints in the absence of a valid prior session or token.
- Repeated requests from the same source IP cycling through endpoints without performing a successful credential challenge first.
Detection Strategies
- Inspect web server and reverse proxy logs for Authorization header values that fail Base64 validation when replayed against a decoder.
- Correlate request rates and source addresses targeting Acer Connect URLs with unauthenticated access patterns observed in network telemetry.
- Deploy signatures in web application firewalls to flag Basic authentication headers whose payload length is not a multiple of four or contains non-Base64 characters.
Monitoring Recommendations
- Enable verbose access logging on any host serving Acer Connect endpoints and forward logs to a centralized analytics platform for retention and correlation.
- Alert on bursts of HTTP 200 responses from endpoints that historically required successful authentication.
- Track outbound connections from systems running Acer Connect to detect post-exploitation activity following a suspected bypass.
How to Mitigate CVE-2026-49197
Immediate Actions Required
- Restrict network exposure of Acer Connect web endpoints to trusted management networks until a fixed version is deployed.
- Apply vendor updates as soon as Acer publishes a patched build referenced in the Acer Knowledge Base Article.
- Audit access logs for malformed Authorization headers and investigate any matching requests for signs of unauthorized access.
Patch Information
Consult the Acer Knowledge Base Article for vendor-supplied fix guidance and supported versions. Apply the corrected build that enforces request rejection when Base64 decoding of the Authorization header fails.
Workarounds
- Place affected endpoints behind a reverse proxy that enforces strict Base64 validation of Authorization headers and returns HTTP 401 on decode failure.
- Require an additional authentication layer such as mutual TLS or a VPN gateway in front of Acer Connect services.
- Block requests at the network edge whose Authorization header values fail standards-compliant Base64 parsing.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
