CVE-2018-20436

HIGHNVD 8.18.1—
EchelonGraph scoreMEDIUM confidence

Score 8.1 from GitHub Security Advisory (severity: HIGH) published 2022-05-14. NVD baseline CVSS 8.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
8.1
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 2%CVSS: 8.1Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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

CVSS v3
8.1
EG Score
8.1(medium)
EPSS
72.5%
KEV
Not listed

Published

December 24, 2018

Last Modified

November 21, 2024

References (4)

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 9× in last 7d / 46× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-22 14:05 UTCEPSS rescore
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  1. 2026-07-05 02:27 UTCEPSS rescore
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  65. 2026-05-27 23:58 UTCEG score recompute
  66. 2026-05-27 23:58 UTCGHSA enrichment
  67. 2026-05-27 13:38 UTCEPSS rescore
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Frequently asked(5)

What is CVE-2018-20436?
CVE-2018-20436 is a high vulnerability published on December 24, 2018. 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…
When was CVE-2018-20436 disclosed?
CVE-2018-20436 was first published in the National Vulnerability Database on December 24, 2018, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2018-20436 actively exploited?
CVE-2018-20436 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 72.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2018-20436?
CVE-2018-20436 has a CVSS v3 base score of 8.1 (NVD).
How do I remediate CVE-2018-20436?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2018-20436, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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