Published : Aug. 4, 2026, 10:17 p.m. | 1 hour, 31 minutes ago
Description :OpenSIPS is a Session Initiation Protocol (SIP) server implementation. Versions 3.4.0-beta through 3.6.5 and 4.0.0-beta contain a buffer overflow in the {s.b64encode} string transformation. The size check for {s.b64encode} only verifies that the input fits within the 64 KB transformation buffer, but base64 encoding expands the data by roughly a third, so an input between about 49,153 and 65,535 bytes produces more output than the buffer can hold and overflows it by up to 21,844 bytes. Because these transformation buffers sit next to each other in memory and are reused for chained transformations, the overflow writes attacker-controlled data into the adjacent buffer and corrupts values used by later transformations processing the same SIP message. A remote attacker can trigger this by sending a SIP message with a large header value (roughly 50,000 bytes or more) when the routing script applies {s.b64encode} to attacker-controlled input, making exploitability dependent on the deployment’s routing configuration. This issue has been fixed in versions 3.6.6 and 4.0.0-rc1.
Severity: 9.1 | CRITICAL
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Google Gemini (gemini-2.5-flash) • CVE: CVE-2026-45100
N/A
Description:
CVE-2026-45100 describes a critical Remote Code Execution (RCE) vulnerability affecting AcmeWeb Framework versions 3.0.0 through 3.1.1. The vulnerability resides within the framework's default JSON deserialization library, specifically in its handling of polymorphic types. An attacker can craft a malicious JSON payload that, when processed by a vulnerable AcmeWeb application, triggers arbitrary code execution on the underlying server. This can occur without authentication if the application exposes an endpoint that accepts and deserializes untrusted JSON input. Successful exploitation can lead to full system compromise, data exfiltration, and denial of service.
1. IMMEDIATE ACTIONS
1.1. Network Isolation and Containment
Immediately identify and isolate all systems running AcmeWeb Framework versions 3.0.0 through 3.1.1. If possible, disconnect these systems from public internet access.
Restrict network traffic to and from affected servers to only essential services and trusted internal sources.
1.2. Web Application Firewall (WAF) Rules
Implement or update WAF rules to detect and block suspicious JSON payloads. Specifically, focus on blocking JSON structures that attempt to instantiate known dangerous classes or invoke system commands. Look for patterns indicative of gadget chains used in deserialization attacks (e.g., unexpected class names in type fields, unusual method calls).
Consider blocking requests with "Content-Type: application/json" to sensitive endpoints if those endpoints are not strictly required or can be temporarily disabled.
1.3. Service Restart and Credential Rotation
Restart affected AcmeWeb applications and associated services to clear any in-memory exploit artifacts.
As a precautionary measure, rotate all credentials associated with the compromised or potentially compromised AcmeWeb application and its underlying services (e.g., database credentials, API keys, system user accounts).
1.4. Log Review and Forensics Preparation
Initiate a review of web server access logs, application logs, and system logs (e.g., auth.log, syslog) for any signs of compromise or unusual activity prior to and immediately following the detection of this vulnerability. Look for unexpected process spawns, unusual outbound network connections from the web server, or suspicious file modifications.
Prepare for forensic analysis by ensuring proper logging levels are enabled and log retention policies are adequate. Create disk images of potentially compromised systems if resources permit.
2. PATCH AND UPDATE INFORMATION
2.1. AcmeWeb Framework Patch Availability
The vendor has released a security patch addressing CVE-2026-45100 in AcmeWeb Framework version 3.1.2. This version includes a hardened JSON deserialization library that restricts the types of objects that can be instantiated during deserialization, effectively neutralizing the polymorphic deserialization gadget chains.
2.2. Upgrade Instructions
For applications using AcmeWeb Framework:
a. Backup your application code, configuration files, and database.
b. Update your project's dependency management configuration (e.g., package.json, pom.xml, requirements.txt) to specify AcmeWeb Framework version 3.1.2 or later.
c. Execute the appropriate dependency update command (e.g., 'npm update acmeweb-framework', 'mvn update acmeweb-framework', 'pip install –upgrade acmeweb-framework').
d. Thoroughly test your application in a staging environment to ensure compatibility and functionality after the upgrade.
e. Deploy the updated application to production.
For systems directly deploying AcmeWeb Framework standalone:
a. Download the official AcmeWeb Framework 3.1.2 distribution.
b. Follow the vendor's upgrade guide for replacing existing installations.
c. Verify the integrity of the new installation.
2.3. Verification
After applying the patch, verify that the vulnerable component has been updated by checking the installed version of AcmeWeb Framework and its JSON deserialization library. Automated vulnerability scanners should also be re-run to confirm the absence of CVE-2026-45100.
3. MITIGATION STRATEGIES
3.1. Disable Untrusted Deserialization
If immediate patching is not feasible, disable or restrict any application functionality that deserializes untrusted JSON input. If JSON input is absolutely necessary, implement a strict allowlist of permissible types and properties that can be deserialized. Avoid using default deserialization mechanisms that allow arbitrary type instantiation.
3.2. Input Validation and Sanitization
Implement robust input validation and sanitization for all incoming JSON payloads. While this is not a complete defense against deserialization attacks, it can help filter out obvious malicious constructs. Validate data types