What is CVE-2018-20436?

CVE-2018-20436 is a high-severity vulnerability in Telegram, classified under Server-Side Request Forgery (SSRF). CVSS score: 8.1/10. Published 2018-12-24.

How severe is CVE-2018-20436?

High severity. CVSS v3 base score is 8.1 out of 10.

SSRF in Telegram

CVE-2018-20436

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

Vulnerability class: SSRF (Server-Side Request Forgery)

EPSS: 0.016 (72.6th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 8.1 (High). Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H.

Affected products

Telegram — versions 4.9.1
Telegram Web — versions 0.7.0
N/a — versions n/a

Weakness classification (CWE)

CWE-918 — Server-Side Request Forgery (SSRF)

References

cve@mitre.org (Exploit, Third Party Advisory, x_refsource_MISC)
cve@mitre.org (Exploit, Third Party Advisory, x_refsource_MISC)

Frequently asked questions

What is CVE-2018-20436?: CVE-2018-20436 is a high-severity vulnerability in Telegram, classified under Server-Side Request Forgery (SSRF). CVSS score: 8.1/10. Published 2018-12-24.
How severe is CVE-2018-20436?: High severity. CVSS v3 base score is 8.1 out of 10.