CVE-2026-34977: Aperi'Solve Steganalysis RCE Vulnerability

CVE-2026-34977 Overview

Aperi'Solve is an open-source steganalysis web platform used for analyzing images and detecting steganography. A critical command injection vulnerability exists in versions prior to 3.2.1 that allows unauthenticated attackers to execute arbitrary commands with root-level privileges within the worker container through a maliciously crafted password field when uploading JPEG images.

The vulnerability stems from unsafe handling of user-supplied password input in the jpseek analyzer module. When a user uploads a JPEG file with an optional password for steganography analysis, this password is directly interpolated into an expect command that is subsequently executed via bash -c without any sanitization or validation.

Critical Impact

Unauthenticated attackers can achieve root-level Remote Code Execution (RCE) inside the worker container with a single HTTP request, enabling full read/write access to all user-uploaded images, analysis results, and plaintext steganography passwords stored on disk.

Affected Products

• Aperi'Solve versions prior to 3.2.1
• Aperi'Solve steganalysis web platform (self-hosted deployments)
• Docker-based Aperi'Solve installations with shared network access to PostgreSQL and Redis

Discovery Timeline

• 2026-04-06 - CVE-2026-34977 published to NVD
• 2026-04-07 - Last updated in NVD database

Technical Details for CVE-2026-34977

Vulnerability Analysis

This command injection vulnerability (CWE-78) allows attackers to execute arbitrary shell commands by exploiting improper input handling in the jpseek analyzer component. When processing JPEG files with password-protected steganographic content, the application passes user-supplied passwords directly into shell command strings without sanitization.

The vulnerable code path involves the construction of an expect command that wraps the jpseek steganography tool. The password parameter is directly embedded into a command string that gets executed through bash -c, creating a classic shell injection vector. An attacker can craft a malicious password containing shell metacharacters and commands that break out of the intended string context and execute arbitrary code.

The impact is particularly severe due to the container's network topology—the worker container shares a Docker network with PostgreSQL and Redis services that lack authentication. This allows successful attackers to pivot laterally, dump database contents, or manipulate the job queue to poison results for other users. If the deployment includes Docker socket mounting or host volume mounts, exploitation could escalate to full host compromise.

Root Cause

The root cause is improper input validation and unsafe command construction in the aperisolve/analyzers/jpseek.py module. The vulnerable code directly interpolates user-supplied password values into a shell command string using f-string formatting:

expect_cmd = (
    f"expect -c 'spawn {jpseek_cmd}; "
    f'expect "Passphrase:"; '
    f'send "{password}\\r"; '
    f"expect eof'"
)
return ["bash", "-c", expect_cmd]

This pattern allows attackers to inject shell commands by including characters like quotes, semicolons, or backticks in the password field.

Attack Vector

The attack vector is network-based and requires no authentication. An attacker can exploit this vulnerability by:

1. Sending an HTTP request to upload a JPEG file to the Aperi'Solve platform
2. Including a maliciously crafted password parameter containing shell metacharacters
3. The server processes the upload and passes the password directly into the expect/bash command chain
4. Arbitrary commands execute with root privileges within the worker container

The following patch shows the security fix that addresses this vulnerability:

         """Build the jpseek command wrapped with expect for password support."""
         extracted_dir = self.get_extracted_dir()
         out = str(extracted_dir / "jpseek.out")
-        jpseek_cmd = f"jpseek {self.img} {out}"
         if password is None:
             password = ""
-        expect_cmd = (
-            f"expect -c 'spawn {jpseek_cmd}; "
-            f'expect "Passphrase:"; '
-            f'send "{password}\\r"; '
-            f"expect eof'"
+        # File paths are quoted with Tcl braces to prevent interpretation of
+        # special characters. The password is passed via an environment variable
+        # (JPSEEK_PASS) to avoid any command injection through string interpolation.
+        expect_script = (
+            f"spawn jpseek {{{self.img}}} {{{out}}}; "
+            'expect "Passphrase:"; '
+            'send "$env(JPSEEK_PASS)\\r"; '
+            "expect eof"
         )
-        return ["bash", "-c", expect_cmd]
+        return ["env", f"JPSEEK_PASS={password}", "expect", "-c", expect_script]

     def _remove_output_artifacts(self, output: str) -> str:
         extracted_dir = self.get_extracted_dir()

Source: GitHub Commit

Detection Methods for CVE-2026-34977

Indicators of Compromise

• Unusual process spawning from the Aperi'Solve worker container, particularly bash, sh, or other shell interpreters with unexpected arguments
• Network connections originating from the worker container to external IP addresses or internal services beyond expected PostgreSQL and Redis communications
• Suspicious entries in application logs showing malformed or unusual password values containing shell metacharacters (;, |, $(), backticks)
• Unexpected file creation or modification within the container filesystem or mounted volumes

Detection Strategies

• Implement web application firewall (WAF) rules to detect and block requests containing shell metacharacters in the password field of image upload endpoints
• Monitor container process execution for unexpected command chains involving expect, bash -c, or other shell invocations
• Deploy network intrusion detection systems (NIDS) to identify unusual outbound traffic patterns from containerized services
• Enable comprehensive application logging to capture all incoming requests with their parameters for forensic analysis

Monitoring Recommendations

• Configure container runtime security monitoring using tools like Falco or SentinelOne Singularity Cloud Workload Security to detect anomalous process behavior
• Establish baseline network traffic patterns for the worker container and alert on deviations, particularly connections to the PostgreSQL and Redis services
• Implement file integrity monitoring on container volumes to detect unauthorized modifications to user-uploaded content or configuration files

How to Mitigate CVE-2026-34977

Immediate Actions Required

• Upgrade Aperi'Solve to version 3.2.1 or later immediately to address this command injection vulnerability
• Review container logs and network traffic for any indicators of compromise prior to patching
• Implement network segmentation to restrict the worker container's access to PostgreSQL and Redis services
• Enable authentication on PostgreSQL and Redis instances if not already configured
• Audit Docker socket and host volume mount configurations to minimize potential escalation paths

Patch Information

The vulnerability is fixed in Aperi'Solve version 3.2.1. The security patch modifies the command construction in aperisolve/analyzers/jpseek.py to pass the password through an environment variable (JPSEEK_PASS) instead of direct string interpolation, and uses Tcl braces for proper quoting of file paths.

Upgrade instructions and release notes are available at the GitHub Release 3.2.1 page. Additional technical details about the fix can be found in the GitHub Security Advisory GHSA-8r22-62p7-9jrp.

Workarounds

• If immediate patching is not possible, disable the JPEG upload functionality or the jpseek analyzer module temporarily
• Implement strict input validation at the application gateway or reverse proxy level to reject requests with shell metacharacters in the password field
• Deploy the worker container with restricted network policies to prevent lateral movement to database services
• Remove Docker socket mounts and minimize host volume mounts to contain potential compromise

# Example: Network policy to isolate worker container
# Apply before patch deployment if using Kubernetes
kubectl apply -f - <<EOF
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: aperisolve-worker-isolation
spec:
  podSelector:
    matchLabels:
      app: aperisolve-worker
  policyTypes:
  - Egress
  egress: []  # Block all egress until patched
EOF