Amazon CloudfrontApplication · Amazon

CVE-2020-36363

CRITICAL · 9.8 CVSS v3.1 Published 2021-08-12
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Amazon AWS CloudFront TLSv1.2_2019 allows TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 and TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384, which some entities consider to be weak ciphers.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

Amazon AWS CloudFront's TLSv1.2_2019 security policy includes CBC-mode cipher suites (TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 and TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) that are considered weak due to known vulnerabilities in CBC mode and the use of older SHA hash functions, potentially exposing traffic to cryptographic attacks.

MitigationReconfigure CloudFront distributions to use a stricter TLS security policy that excludes CBC-mode ciphers, such as TLSv1.2_2021 or a custom policy allowing only GCM-based cipher suites.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Amazon CloudfrontApplication
Affected:= 1.2_2019

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. List CloudFront distributions and viewer TLS policies
    Use the AWS CLI command: aws cloudfront list-distributions --query 'DistributionList.Items[*].{Id:Id,Arn:ARN,ViewerCertificate:ViewerCertificate}'
    Affected if Any distribution shows TLSv1.2_2019 as the minimum TLS version or in the SSLSupportMethod
  2. Check the specific TLS security policy configured
    Run: aws cloudfront get-distribution-config --id <DISTRIBUTION_ID> --query 'DistributionConfig.ViewerCertificate.MinimumProtocolVersion'
    Affected if The MinimumProtocolVersion field returns TLSv1.2_2019
  3. Inspect custom TLS policies for weak CBC ciphers
    If using a custom policy, examine the configured cipher suites using: aws cloudfront list-cloud-front-origin-access-identities (for OAI) or check the SSLSupportMethod configuration. Review whether the policy explicitly includes TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 or TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384
    Affected if The configured policy contains either TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 or TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384 cipher suites

A distribution is affected if it uses TLSv1.2_2019 as the minimum TLS protocol version or has a custom policy that includes the weak CBC-mode cipher suites TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 or TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Reconfigure CloudFront distributions to use a stricter TLS security policy that excludes CBC-mode ciphers, such as TLSv1.2_2021 or a custom policy allowing only GCM-based cipher suites.

Fix this in Amazon Cloudfront Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,060
Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,696.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2020-36363 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2020-36363 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data