CVE-2026-103849 Overview
CVE-2026-103849 affects Adobe Commerce through improper neutralization of special elements used in a template engine [CWE-1336]. Attackers can achieve arbitrary code execution in the context of the current user, potentially gaining elevated access or control over the victim's account or session. Exploitation requires no user interaction, and the vulnerability's scope is changed, meaning impact extends beyond the vulnerable component.
Critical Impact
Unauthenticated remote attackers can execute arbitrary code across trust boundaries, compromising Adobe Commerce storefronts and backend sessions without any user interaction.
Affected Products
- Adobe Commerce (see Adobe Security Bulletin APSB26-153 for affected versions)
- Adobe Commerce on-premise deployments
- Adobe Commerce Cloud deployments
Discovery Timeline
- 2026-10-13 - CVE-2026-103849 published to the National Vulnerability Database
- 2026-10-15 - Last updated in NVD database
Technical Details for CVE-2026-103849
Vulnerability Analysis
CVE-2026-103849 is a server-side template injection flaw in Adobe Commerce. The platform's template engine fails to neutralize special syntax elements before rendering user-controllable input. When attacker-supplied data is processed by the template engine, embedded directives execute within the application context rather than being treated as inert data.
The scope-changed classification indicates that successful exploitation crosses a security boundary. An attacker reaching the vulnerable template parser can influence components beyond the originally authorized context, which typically translates to full application compromise and lateral movement into connected services.
Because the attack vector is network-based and requires no privileges or user interaction, the vulnerability can be weaponized against internet-facing Adobe Commerce storefronts at scale. Confidentiality, integrity, and availability of the host application and dependent services are all at risk.
Root Cause
The root cause is improper neutralization of special elements used in a template engine [CWE-1336]. User-supplied input reaches the template rendering pipeline without sufficient sanitization or output encoding. Template directives in the input are interpreted as code, allowing attackers to inject expressions that the engine evaluates on the server.
Attack Vector
An unauthenticated attacker crafts an HTTP request containing template syntax directed at a vulnerable Adobe Commerce endpoint. The template engine parses the injected payload and evaluates attacker-controlled expressions, producing arbitrary code execution in the running user context. Full technical details are reserved by Adobe pending patch adoption; refer to the Adobe Security Update APSB26-153 for vendor-provided guidance.
Stop Remote Code Execution Before It Runs
Singularity™ Endpoint detects and blocks exploit attempts at machine speed, including zero-days and novel attack techniques.
Stop Exploit AttemptsDetection Methods for CVE-2026-103849
Indicators of Compromise
- Unexpected PHP processes spawned by the web server user, such as www-data or nginx, following HTTP requests to Commerce endpoints
- Outbound network connections from Adobe Commerce hosts to unknown IPs shortly after inbound POST or GET requests containing template delimiters
- New or modified files under pub/, app/code/, or var/ directories outside normal deployment windows
- Anomalous administrator sessions or privilege changes within the Commerce admin panel
Detection Strategies
- Inspect web server access logs for request parameters containing template syntax such as {{, }}, #{, or ${ targeting Commerce routes
- Correlate web request telemetry with child process creation on Commerce application servers to surface injection-to-execution chains
- Deploy signature and behavioral rules that flag server-side template injection patterns in HTTP request bodies and query strings
Monitoring Recommendations
- Enable verbose request logging on Commerce front controllers and forward logs to a centralized analytics platform for retention and search
- Monitor file integrity on Adobe Commerce document roots and configuration directories
- Alert on new scheduled tasks, cron entries, or Magento CLI invocations originating from non-administrative sources
How to Mitigate CVE-2026-103849
Immediate Actions Required
- Apply the Adobe-released security update referenced in APSB26-153 to all Adobe Commerce instances
- Restrict administrative and API endpoints to known IP ranges while patch deployment is in progress
- Review web server and application logs for evidence of exploitation attempts predating patch installation
- Rotate secrets, API keys, and administrator credentials on any host suspected of exposure
Patch Information
Adobe published fixes for CVE-2026-103849 in security bulletin APSB26-153. Administrators must upgrade to the vendor-specified Adobe Commerce release that addresses the template engine neutralization flaw. Consult the Adobe Security Update APSB26-153 for the exact fixed versions and upgrade procedures.
Workarounds
- Place a web application firewall in front of Adobe Commerce and block requests containing template delimiter syntax in parameters
- Disable or restrict access to Commerce features that process user-supplied template content until the patch is applied
- Enforce strict Content Security Policy and least-privilege file system permissions on the Commerce application user
# Example WAF rule concept to block template delimiters in query strings
# Adapt to your WAF syntax (ModSecurity, AWS WAF, Cloudflare, etc.)
SecRule ARGS "@rx (\{\{|\}\}|\$\{|#\{)" \
"id:1030849,phase:2,deny,status:403,msg:'Possible SSTI targeting Adobe Commerce CVE-2026-103849'"
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
