Telegram
CVE-2018-20436
HIGH
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V4 - API and Web Service URL allowlisting, SSRF prevention
MITRE ATT&CK
2 techniques across 2 tactics: Initial Access, Credential Access The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Impact | CVSS score of 8.1 (HIGH). Attack characteristics: network attack vector, high complexity, no privileges required, no user interaction not required. Public proof-of-concept exploit code is available. |
| Exploit ScenarioDerived | A remote attacker could make the server perform requests to unintended internal or external resources by sending crafted requests to the affected application. No authentication is required to exploit this vulnerability. |
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Alert meAnalysisAI
The "secret chat" feature in Telegram 4.9.1 for Android has a "side channel" in which Telegram servers send GET requests for URLs typed while composing a chat message, before that chat message is. Rated high severity (CVSS 8.1), this vulnerability is remotely exploitable, no authentication required. Public exploit code available and no vendor patch available.
RemediationAI
No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Validate and allowlist destination URLs, block requests to internal networks, use network segmentation.
Affects your stack
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Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
This vulnerability is classified as Server-Side Request Forgery (SSRF) (CWE-918), which allows attackers to make the server perform requests to unintended internal or external resources. The "secret chat" feature in Telegram 4.9.1 for Android has a "side channel" in which Telegram servers send GET requests for URLs typed while composing a chat message, before that chat message is sent. There are also GET requests to other URLs on the same web server. This also affects one or more other Telegram products, such as Telegram Web-version 0.7.0. In addition, it can be interpreted as an SSRF issue. NOTE: a third party has reported that potentially unwanted behavior is caused by misconfiguration of the "Secret chats > Preview links" setting Affected products include: Telegram, Telegram Web. Version information: version 0.7.0..
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- Exploit and PoC references, threat intelligence from 22 sources
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Severity by source
AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
DescriptionNVD
The "secret chat" feature in Telegram 4.9.1 for Android has a "side channel" in which Telegram servers send GET requests for URLs typed while composing a chat message, before that chat message is sent. There are also GET requests to other URLs on the same web server. This also affects one or more other Telegram products, such as Telegram Web-version 0.7.0. In addition, it can be interpreted as an SSRF issue. NOTE: a third party has reported that potentially unwanted behavior is caused by misconfiguration of the "Secret chats > Preview links" setting
Threat Intelligence Overview
NVD
CVE.org
EPSS
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Server-Side Request Forgery exploits applications that fetch remote resources based on user-supplied URLs.
Affected Products (CPE)NVD
Telegram Desktop before 1.5.12 on Windows, and the Telegram applications for Android, iOS, and Linux, is vulnerable to a
One-click account takeover in Telegram Desktop before 7.2.9, where the Core::Sandbox inter-process communication layer f
Telegram Desktop before 6.9.4 fails to escape inline-keyboard button text when a chat is exported to HTML, so attacker-c
Telegram Desktop versions up to 2.9.2 is affected by allocation of resources without limits or throttling (CVSS 7.5).
Telegram Desktop (aka tdesktop) 1.3.14 might allow attackers to cause a denial of service (assertion failure and applica
Telegram Android <7.1.0 (2090), Telegram iOS <7.1, and Telegram macOS <7.1 are affected by a Stack Based Overflow in the
Telegram Android <7.1.0 (2090), Telegram iOS <7.1, and Telegram macOS <7.1 are affected by a Heap Buffer Overflow in the
Telegram Desktop (aka tdesktop) 1.3.14, and Telegram 3.3.0.0 WP8.1 on Windows, leaks end-user public and private IP addr
Telegram Web 15.3.1 allows XSS via a certain payload derived from a Target Corporation website. Rated medium severity (C
Telegram Web K Alpha before 0.7.2 mishandles the characters in a document extension. Rated critical severity (CVSS 9.8),
Telegram Desktop (aka tdesktop) 1.3.16 alpha, when "Use proxy" is enabled, sends credentials and application data in cle
The Telegram app 7.6.2 for iOS allows remote authenticated users to cause a denial of service (application crash) if the
GitHub PoC
Exploit-DB