HOMEVULNERABILITIESCVE-2018-20436
HIGH

CVE-2018-20436

CWE-918Published: December 24, 2018· Updated: Jun 17, 2026

8.1
CVSS v3.1

Official Description

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

NVD Source

Technical Analysis

CVE-2018-20436 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 8.1.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityHigh
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected Vendors & Products

telegram2 product(s)
telegramweb
Source: NVD CPE · 2 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

ADVISORYhttps://misteralfa-hack.blogspot.com/2018/12/abusando-de-telegram-para-conseguir-una.html
ADVISORYhttps://misteralfa-hack.blogspot.com/2018/12/telegram-siempre-in-middle.html
ADVISORYhttps://misteralfa-hack.blogspot.com/2018/12/abusando-de-telegram-para-conseguir-una.html
ADVISORYhttps://misteralfa-hack.blogspot.com/2018/12/telegram-siempre-in-middle.html

All References (4)

→
https://misteralfa-hack.blogspot.com/2018/12/abusando-de-telegram-para-conseguir-una.htmlExploit · Third Party Advisory
→
https://misteralfa-hack.blogspot.com/2018/12/telegram-siempre-in-middle.htmlExploit · Third Party Advisory
→
https://misteralfa-hack.blogspot.com/2018/12/abusando-de-telegram-para-conseguir-una.htmlExploit · Third Party Advisory
→
https://misteralfa-hack.blogspot.com/2018/12/telegram-siempre-in-middle.htmlExploit · Third Party Advisory

Quick Facts

CVE IDCVE-2018-20436
CVSS Score8.1 / 10
SeverityHIGH
WeaknessCWE-918
CISA KEVNo
Affected1 vendor(s)
PublishedDec 24, 2018

Related CVEs (CWE-918)

CVE-2025-2828
10.0
CVE-2026-26138
10.0
CVE-2025-54122
10.0
CVE-2026-62643
10.0
CVE-2026-40114
10.0
CVE-2026-13773
10.0

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2018-20436 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWatch. CVE data is provided under the NVD usage policy.
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