9.1
CRITICAL
CVE-2021-43837
Hashicorp Vault vault-cli Jinja2 Template Injection Remote Code Execution
Description

vault-cli is a configurable command-line interface tool (and python library) to interact with Hashicorp Vault. In versions before 3.0.0 vault-cli features the ability for rendering templated values. When a secret starts with the prefix `!template!`, vault-cli interprets the rest of the contents of the secret as a Jinja2 template. Jinja2 is a powerful templating engine and is not designed to safely render arbitrary templates. An attacker controlling a jinja2 template rendered on a machine can trigger arbitrary code, making this a Remote Code Execution (RCE) risk. If the content of the vault can be completely trusted, then this is not a problem. Otherwise, if your threat model includes cases where an attacker can manipulate a secret value read from the vault using vault-cli, then this vulnerability may impact you. In 3.0.0, the code related to interpreting vault templated secrets has been removed entirely. Users are advised to upgrade as soon as possible. For users unable to upgrade a workaround does exist. Using the environment variable `VAULT_CLI_RENDER=false` or the flag `--no-render` (placed between `vault-cli` and the subcommand, e.g. `vault-cli --no-render get-all`) or adding `render: false` to the vault-cli configuration yaml file disables rendering and removes the vulnerability. Using the python library, you can use: `vault_cli.get_client(render=False)` when creating your client to get a client that will not render templated secrets and thus operates securely.

INFO

Published Date :

Dec. 16, 2021, 7:15 p.m.

Last Modified :

Nov. 21, 2024, 6:29 a.m.

Source :

[email protected]

Remotely Exploitable :

Yes !

Impact Score :

6.0

Exploitability Score :

2.3
Affected Products

The following products are affected by CVE-2021-43837 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Vault-cli_project vault-cli
: Total Affected Vendor : 1 | Products : 1
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2021-43837.

URL Resource
https://github.com/peopledoc/vault-cli/commit/3ba3955887fd6b7d4d646c8b260f21cebf5db852 Patch Third Party Advisory
https://github.com/peopledoc/vault-cli/security/advisories/GHSA-q34h-97wf-8r8j Exploit Mitigation Third Party Advisory
https://podalirius.net/en/publications/grehack-2021-optimizing-ssti-payloads-for-jinja2/ Exploit Third Party Advisory
https://github.com/peopledoc/vault-cli/commit/3ba3955887fd6b7d4d646c8b260f21cebf5db852 Patch Third Party Advisory
https://github.com/peopledoc/vault-cli/security/advisories/GHSA-q34h-97wf-8r8j Exploit Mitigation Third Party Advisory
https://podalirius.net/en/publications/grehack-2021-optimizing-ssti-payloads-for-jinja2/ Exploit Third Party Advisory

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2021-43837 vulnerability anywhere in the article.

The following table lists the changes that have been made to the CVE-2021-43837 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • CVE Modified by af854a3a-2127-422b-91ae-364da2661108

    Nov. 21, 2024

    Action Type Old Value New Value
    Added Reference https://github.com/peopledoc/vault-cli/commit/3ba3955887fd6b7d4d646c8b260f21cebf5db852
    Added Reference https://github.com/peopledoc/vault-cli/security/advisories/GHSA-q34h-97wf-8r8j
    Added Reference https://podalirius.net/en/publications/grehack-2021-optimizing-ssti-payloads-for-jinja2/
  • CVE Modified by [email protected]

    May. 14, 2024

    Action Type Old Value New Value
  • Reanalysis by [email protected]

    Aug. 09, 2022

    Action Type Old Value New Value
    Added CWE NIST CWE-94
  • CPE Deprecation Remap by [email protected]

    Feb. 08, 2022

    Action Type Old Value New Value
    Changed CPE Configuration OR *cpe:2.3:a:ukg:vault-cli:*:*:*:*:*:python:*:* versions from (including) 0.7.0 from (excluding) 3.0.0 OR *cpe:2.3:a:vault-cli_project:vault-cli:*:*:*:*:*:python:*:* versions from (including) 0.7.0 from (excluding) 3.0.0
  • Initial Analysis by [email protected]

    Dec. 30, 2021

    Action Type Old Value New Value
    Added CVSS V2 NIST (AV:N/AC:L/Au:S/C:C/I:C/A:C)
    Added CVSS V3.1 NIST AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
    Changed Reference Type https://github.com/peopledoc/vault-cli/commit/3ba3955887fd6b7d4d646c8b260f21cebf5db852 No Types Assigned https://github.com/peopledoc/vault-cli/commit/3ba3955887fd6b7d4d646c8b260f21cebf5db852 Patch, Third Party Advisory
    Changed Reference Type https://github.com/peopledoc/vault-cli/security/advisories/GHSA-q34h-97wf-8r8j No Types Assigned https://github.com/peopledoc/vault-cli/security/advisories/GHSA-q34h-97wf-8r8j Exploit, Mitigation, Third Party Advisory
    Changed Reference Type https://podalirius.net/en/publications/grehack-2021-optimizing-ssti-payloads-for-jinja2/ No Types Assigned https://podalirius.net/en/publications/grehack-2021-optimizing-ssti-payloads-for-jinja2/ Exploit, Third Party Advisory
    Added CPE Configuration OR *cpe:2.3:a:ukg:vault-cli:*:*:*:*:*:python:*:* versions from (including) 0.7.0 up to (excluding) 3.0.0
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2021-43837 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2021-43837 weaknesses.

CAPEC-3: Using Leading 'Ghost' Character Sequences to Bypass Input Filters Using Leading 'Ghost' Character Sequences to Bypass Input Filters CAPEC-6: Argument Injection Argument Injection CAPEC-7: Blind SQL Injection Blind SQL Injection CAPEC-8: Buffer Overflow in an API Call Buffer Overflow in an API Call CAPEC-9: Buffer Overflow in Local Command-Line Utilities Buffer Overflow in Local Command-Line Utilities CAPEC-10: Buffer Overflow via Environment Variables Buffer Overflow via Environment Variables CAPEC-13: Subverting Environment Variable Values Subverting Environment Variable Values CAPEC-14: Client-side Injection-induced Buffer Overflow Client-side Injection-induced Buffer Overflow CAPEC-24: Filter Failure through Buffer Overflow Filter Failure through Buffer Overflow CAPEC-28: Fuzzing Fuzzing CAPEC-34: HTTP Response Splitting HTTP Response Splitting CAPEC-42: MIME Conversion MIME Conversion CAPEC-43: Exploiting Multiple Input Interpretation Layers Exploiting Multiple Input Interpretation Layers CAPEC-45: Buffer Overflow via Symbolic Links Buffer Overflow via Symbolic Links CAPEC-46: Overflow Variables and Tags Overflow Variables and Tags CAPEC-47: Buffer Overflow via Parameter Expansion Buffer Overflow via Parameter Expansion CAPEC-51: Poison Web Service Registry Poison Web Service Registry CAPEC-52: Embedding NULL Bytes Embedding NULL Bytes CAPEC-53: Postfix, Null Terminate, and Backslash Postfix, Null Terminate, and Backslash CAPEC-64: Using Slashes and URL Encoding Combined to Bypass Validation Logic Using Slashes and URL Encoding Combined to Bypass Validation Logic CAPEC-67: String Format Overflow in syslog() String Format Overflow in syslog() CAPEC-71: Using Unicode Encoding to Bypass Validation Logic Using Unicode Encoding to Bypass Validation Logic CAPEC-72: URL Encoding URL Encoding CAPEC-76: Manipulating Web Input to File System Calls Manipulating Web Input to File System Calls CAPEC-78: Using Escaped Slashes in Alternate Encoding Using Escaped Slashes in Alternate Encoding CAPEC-79: Using Slashes in Alternate Encoding Using Slashes in Alternate Encoding CAPEC-80: Using UTF-8 Encoding to Bypass Validation Logic Using UTF-8 Encoding to Bypass Validation Logic CAPEC-83: XPath Injection XPath Injection CAPEC-84: XQuery Injection XQuery Injection CAPEC-101: Server Side Include (SSI) Injection Server Side Include (SSI) Injection CAPEC-105: HTTP Request Splitting HTTP Request Splitting CAPEC-108: Command Line Execution through SQL Injection Command Line Execution through SQL Injection CAPEC-120: Double Encoding Double Encoding CAPEC-135: Format String Injection Format String Injection CAPEC-250: XML Injection XML Injection CAPEC-267: Leverage Alternate Encoding Leverage Alternate Encoding CAPEC-273: HTTP Response Smuggling HTTP Response Smuggling CAPEC-35: Leverage Executable Code in Non-Executable Files Leverage Executable Code in Non-Executable Files CAPEC-77: Manipulating User-Controlled Variables Manipulating User-Controlled Variables CAPEC-242: Code Injection Code Injection
Exploit Prediction

EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days.

9.55 }} -3.22%

score

0.92106

percentile

CVSS31 - Vulnerability Scoring System
Attack Vector
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Latest DB Update: Jun. 27, 2025 12:58