CVE-2026-1089: GoAnywhere MFT Information Disclosure Flaw

CVE-2026-1089 Overview

CVE-2026-1089 is an Injection vulnerability (CWE-74) affecting Fortra's GoAnywhere Managed File Transfer (MFT) prior to version 7.10.0. The vulnerability exists in the handling of user-controlled HTTP headers, allowing remote attackers to trigger DNS lookups, DNS rebinding attacks, and information disclosure without requiring authentication.

GoAnywhere MFT is a widely deployed enterprise managed file transfer solution used by organizations to securely exchange sensitive data. This vulnerability in the HTTP header processing could allow attackers to manipulate server-side requests and potentially exfiltrate sensitive information or redirect internal DNS queries to attacker-controlled infrastructure.

Critical Impact

Unauthenticated attackers can exploit user-controlled HTTP headers to perform DNS rebinding attacks and information disclosure in GoAnywhere MFT environments.

Affected Products

• Fortra GoAnywhere Managed File Transfer versions prior to 7.10.0
• All GoAnywhere MFT deployments with exposed HTTP endpoints
• Both on-premises and hosted GoAnywhere MFT installations

Discovery Timeline

• 2026-04-21 - CVE-2026-1089 published to NVD
• 2026-04-23 - Last updated in NVD database

Technical Details for CVE-2026-1089

Vulnerability Analysis

This vulnerability stems from improper injection neutralization in Fortra's GoAnywhere MFT when processing HTTP headers. The application fails to adequately validate and sanitize user-supplied data within HTTP header values before using them in server-side operations that involve DNS resolution.

The network-accessible attack vector means that any attacker with network access to the GoAnywhere MFT web interface can potentially exploit this vulnerability. The attack requires no user interaction and can be conducted without any authentication, making it particularly concerning for internet-facing deployments.

Successful exploitation enables attackers to perform DNS lookup triggering, which can be used for reconnaissance or to establish out-of-band communication channels. The DNS rebinding capability is particularly dangerous as it can potentially bypass same-origin policy restrictions and access internal network resources. Information disclosure through this vector may reveal internal infrastructure details, network topology, or other sensitive configuration data.

Root Cause

The root cause is an Injection vulnerability (CWE-74) where user-controlled input in HTTP headers is not properly neutralized before being used in DNS-related operations. The application trusts header values provided by clients and uses them directly in server-side requests without adequate validation or sanitization. This allows attackers to inject malicious values that influence the application's behavior when making outbound connections or DNS queries.

Attack Vector

The attack exploits the network-accessible HTTP interface of GoAnywhere MFT. An attacker crafts HTTP requests with specially manipulated header values designed to trigger DNS lookups to attacker-controlled domains. This can be accomplished through:

1. DNS Exfiltration: Encoding sensitive data in DNS queries to attacker-controlled nameservers
2. DNS Rebinding: Manipulating DNS responses to bypass network security controls
3. Infrastructure Reconnaissance: Triggering DNS lookups to map internal network topology

The vulnerability requires no authentication, meaning any network-accessible instance is potentially at risk. The attack is conducted remotely with low complexity, requiring only the ability to send crafted HTTP requests to the target server.

Detection Methods for CVE-2026-1089

Indicators of Compromise

• Unusual outbound DNS queries from GoAnywhere MFT servers to unfamiliar external domains
• Anomalous HTTP request patterns with manipulated or suspicious header values
• DNS query logs showing requests to domains associated with known attacker infrastructure
• Unexpected network connections originating from the GoAnywhere MFT application tier

Detection Strategies

• Monitor outbound DNS traffic from GoAnywhere MFT servers for queries to unusual or newly registered domains
• Implement HTTP header inspection at the web application firewall to detect injection patterns
• Enable detailed logging of HTTP requests to GoAnywhere MFT and analyze for header manipulation attempts
• Deploy network detection rules to identify DNS rebinding attack patterns

Monitoring Recommendations

• Configure SentinelOne to monitor GoAnywhere MFT processes for anomalous network behavior
• Establish baseline DNS query patterns for GoAnywhere servers and alert on deviations
• Review web server access logs for requests with abnormally long or encoded header values
• Set up alerts for GoAnywhere MFT servers initiating DNS queries to external resolvers outside of normal operations

How to Mitigate CVE-2026-1089

Immediate Actions Required

• Upgrade Fortra GoAnywhere MFT to version 7.10.0 or later immediately
• Restrict network access to GoAnywhere MFT administrative interfaces using firewall rules
• Review and audit current GoAnywhere MFT deployments to identify internet-exposed instances
• Enable enhanced logging to detect potential exploitation attempts

Patch Information

Fortra has addressed this vulnerability in GoAnywhere MFT version 7.10.0. Organizations should apply this update as soon as possible. Detailed patch information is available in the Fortra Security Advisory FI-2026-005.

Before upgrading production systems, ensure proper backup procedures are in place and test the upgrade in a non-production environment when possible.

Workarounds

• Implement egress DNS filtering to restrict GoAnywhere MFT servers from resolving arbitrary external domains
• Deploy a web application firewall with rules to sanitize or block suspicious HTTP header values
• Place GoAnywhere MFT behind a reverse proxy that strips or validates potentially dangerous headers
• Segment GoAnywhere MFT servers from sensitive internal network resources to limit DNS rebinding impact

# Example: Restrict outbound DNS for GoAnywhere MFT server using iptables
# Allow DNS only to trusted internal resolvers
iptables -A OUTPUT -p udp --dport 53 -d 10.0.0.53 -j ACCEPT
iptables -A OUTPUT -p tcp --dport 53 -d 10.0.0.53 -j ACCEPT
iptables -A OUTPUT -p udp --dport 53 -j DROP
iptables -A OUTPUT -p tcp --dport 53 -j DROP