CVE-2020-36363Network attack vector

Weak TLS protection via permitted CBC suites

Published Aug 12, 2021 · Updated Aug 4, 2024

Weak cryptography in Amazon CloudFront TLSv1.2_2019 allows remote attackers to negotiate two CBC-mode cipher suites over viewer connections. The security policy's cipher allowlist includes ECDHE-RSA-AES128-SHA256 and ECDHE-RSA-AES256-SHA384 rather than restricting negotiation to AEAD suites. Exposure requires a distribution using that policy and a client offering one of those suites; public sources document no concrete attack or demonstrated data compromise.

CVSS severity9.8
Critical
EPSS probability0.71%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Weak cryptography in Amazon CloudFront TLSv1.2_2019 allows remote attackers to negotiate two CBC-mode cipher suites over viewer connections. The security policy's cipher allowlist includes ECDHE-RSA-AES128-SHA256 and ECDHE-RSA-AES256-SHA384 rather than restricting negotiation to AEAD suites. Exposure requires a distribution using that policy and a client offering one of those suites; public sources document no concrete attack or demonstrated data compromise.

The record

CVE
CVE-2020-36363
Published
Aug 12, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-327
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 12, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.8NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5NIST National Vulnerability DatabaseAV:N/AC:L/Au:N/C:P/I:P/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-327Use of a Broken or Risky Cryptographic Algorithm

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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