CVE-2021-32700: Supply Chain Attack in Ballerina-lang
Platform
other
Component
ballerina-lang
Fixed in
1.2.15
4.0.1
CVE-2021-32700 describes a critical supply chain vulnerability affecting Ballerina, an open-source programming language and platform. This vulnerability allows attackers to perform a man-in-the-middle (MiTM) attack against users by substituting or modifying packages retrieved from the Ballerina Central (BC) repository, potentially injecting malicious code into Ballerina executables. Versions 1.2.x and SwanLake releases up to alpha 3 are affected, with a fix available in Ballerina 1.2.14 and SwanLake alpha4.
Impact and Attack Scenarios
The core of this vulnerability lies in the lack of TLS encryption and certificate verification for HTTP connections when retrieving packages from Ballerina Central. An attacker positioned between the user and BC can intercept the package requests, substitute them with malicious versions, and effectively inject arbitrary code into the user's Ballerina applications. This could lead to complete compromise of the application, data exfiltration, or even remote code execution on the system running the application. The impact is particularly severe because Ballerina is designed for cloud application development, meaning affected applications are likely deployed in production environments and handle sensitive data. This vulnerability shares similarities with other supply chain attacks where malicious packages are introduced into trusted repositories, highlighting the importance of secure package management practices.
Exploitation Context
CVE-2021-32700 was publicly disclosed on June 22, 2021. While no active exploitation campaigns have been definitively confirmed, the critical CVSS score (9.1) and the potential for widespread impact make it a high-priority vulnerability. There are currently no known public proof-of-concept exploits. The vulnerability has been added to the CISA KEV catalog, indicating a heightened concern regarding potential exploitation. The ease of performing a MiTM attack suggests that exploitation is possible if an attacker gains access to the network traffic between users and Ballerina Central.
Threat Intelligence
Exploit Status
EPSS
0.12% (31% percentile)
CVSS Vector
What do these metrics mean?
- Attack Vector
- Network — remotely exploitable over the internet. No physical or local access required. Widest attack surface.
- Attack Complexity
- Low — no special conditions required. Attacker can exploit reliably without depending on rare configurations or timing.
- Privileges Required
- None — unauthenticated. No login or credentials needed to exploit.
- User Interaction
- None — attack is automatic and silent. Victim does nothing: no click, no file open.
- Scope
- Unchanged — impact is limited to the vulnerable component itself.
- Confidentiality
- High — complete confidentiality loss. Attacker can read all data: credentials, keys, personal data.
- Integrity
- High — attacker can write, modify, or delete any data: databases, config files, or code.
- Availability
- None — no availability impact. Service remains fully operational.
Affected Software
Weakness Classification (CWE)
Timeline
- Reserved
- Published
- Modified
- EPSS updated
Mitigation and Workarounds
The primary mitigation for CVE-2021-32700 is to upgrade to a patched version of Ballerina. Upgrade to version 1.2.14 or SwanLake alpha4 to ensure TLS encryption and certificate verification are enforced during package retrieval. If an immediate upgrade is not feasible, consider implementing a temporary workaround by configuring your network to block or inspect traffic to Ballerina Central. Furthermore, review your Ballerina project dependencies and ensure you are only using trusted package sources. After upgrading, verify the fix by attempting to retrieve a package from Ballerina Central while monitoring network traffic to confirm that the connection is encrypted and certificate validation is occurring.
How to fix
Update Ballerina to version 1.2.14 or SwanLake alpha4 or higher. This corrects the security vulnerability that allows man-in-the-middle (MitM) attacks when downloading packages, preventing the injection of malicious code.
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Frequently asked questions
What is CVE-2021-32700 — Supply Chain Attack in Ballerina-lang?
CVE-2021-32700 is a critical vulnerability in Ballerina versions ≤ SL-alpha4 that allows attackers to perform a MiTM attack and inject malicious code via package substitution from Ballerina Central due to missing TLS encryption and certificate verification.
Am I affected by CVE-2021-32700 in Ballerina-lang?
You are affected if you are using Ballerina versions 1.2.x or SwanLake releases up to alpha 3. Check your version and upgrade accordingly.
How do I fix CVE-2021-32700 in Ballerina-lang?
Upgrade to Ballerina version 1.2.14 or SwanLake alpha4 to ensure TLS encryption and certificate verification are enforced during package retrieval.
Is CVE-2021-32700 being actively exploited?
While no active exploitation campaigns have been definitively confirmed, the critical CVSS score and potential impact warrant immediate attention and mitigation.
Where can I find the official Ballerina advisory for CVE-2021-32700?
Refer to the official Ballerina security advisory: https://ballerina.io/blog/security-advisory-cve-2021-32700/
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