dbcve.org
TengineApplication · Alibaba

CVE-2020-21699

HIGH · 7.5 CVSS v3.1 Published 2023-08-22
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
Remediation priority · High
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
The web server Tengine 2.2.2 developed in the Nginx version from 0.5.6 thru 1.13.2 is vulnerable to an integer overflow vulnerability in the nginx range filter module, resulting in the leakage of potentially sensitive information triggered by specially crafted requests.

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 · high confidence

Tengine 2.2.2 (based on Nginx versions 0.5.6 through 1.13.2) contains an integer overflow vulnerability in the HTTP range filter module. By sending specially crafted HTTP range requests, an attacker can trigger the overflow and potentially leak sensitive information from server memory or files.

MitigationUpgrade Tengine to a version beyond 2.2.2 or upgrade Nginx to version 1.13.3 or later, which contain the fix for the integer overflow in the range filter module.

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
TengineApplication
Affected:= 2.2.2

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
None
Availability
None

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

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. Identify Tengine version
    Run ' tengine -v ' or ' /usr/sbin/tengine -v ' to get the installed version number. Compare it to the affected version 2.2.2.
    Affected if The version displayed is exactly 2.2.2
  2. Verify the HTTP range filter module is present
    Run ' tengine -V ' or check for the '--with-http_range_filter_module' flag in the compile-time configuration. Also check for 'ngx_http_range_filter_module' in the compiled modules.
    Affected if The range filter module is compiled into the binary (Tengine 2.2.2 includes this module by default)
  3. Inspect Tengine configuration for range request handling
    Check the main configuration file (typically /etc/tengine/nginx.conf or /etc/nginx/nginx.conf) for any 'add_header Accept-Ranges' directives or 'max_ranges' settings that indicate range request processing is active.
    Affected if Range request handling is explicitly enabled or default settings allow arbitrary range requests
  4. Test for integer overflow in range request parsing
    Send a crafted HTTP request with an abnormally large range header value, such as 'Range: bytes=18446744073709551615-' and observe the server response. A vulnerable server may return an error, crash, or leak unexpected data.
    Affected if The server accepts and processes the range request without proper bounds validation, potentially exposing memory contents

You are affected if running Tengine version 2.2.2 with the HTTP range filter module enabled and processing range requests.

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.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade Tengine to a version beyond 2.2.2 or upgrade Nginx to version 1.13.3 or later, which contain the fix for the integer overflow in the range filter module.

Recommended fix Moderate confidence

A Tengine version newer than 2.2.2 that includes the patched Nginx range filter module (check Tengine security advisories for the exact fixed version)

  1. Check the official Tengine releases page at github.com/alibaba/tengine for available versions
  2. Identify the Tengine version that includes the fix for CVE-2020-21699 (the fix is included in versions after 2.2.2 that patched the Nginx range filter integer overflow)
  3. Review Tengine changelogs or security advisories to confirm which specific version contains the fix for this vulnerability
  4. Plan and schedule the upgrade, ensuring compatibility with your existing configuration
  5. Back up your current Tengine configuration files
  6. Perform the upgrade following standard Tengine upgrade procedures
  7. After upgrading, verify the range filter module functions correctly and test that specially crafted range requests no longer trigger the integer overflow
Caveat Review release notes between 2.2.2 and the target version for any configuration or module changes that may require adjustments

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Tengine Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA1.0 h
9.0 hours of engineering $1,600
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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-2020-21699 in production — separate from our analysis above.

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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