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Debian LinuxOperating system · Debian

CVE-2021-38165

MEDIUM · 5.3 CVSS v3.1 Published 2021-08-07
Fix available
A fix is available. Upgrade to after 2.8.9 or later.
See remediation →
60/100
Remediation priority · Elevated
Remotely reachable No privileges

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
Lynx through 2.8.9 mishandles the userinfo subcomponent of a URI, which allows remote attackers to discover cleartext credentials because they may appear in SNI data.

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

Lynx through version 2.8.9 improperly handles the userinfo subcomponent of URIs, causing embedded credentials (username:password@) to be exposed in Server Name Indication (SNI) data during TLS handshakes. This allows remote network attackers observing the TLS handshake to intercept cleartext credentials.

MitigationUpgrade to Lynx 2.9.0 or later which properly handles URI userinfo. As a temporary workaround, avoid embedding credentials in URLs when using Lynx.

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
Debian LinuxOperating system
Affected:= 9.0= 10.0
FedoraOperating system
Affected:= 33= 34= 35
LynxApplication
Affected:<= 2.8.9

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
High
Privileges
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/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. Check installed Lynx version
    Run 'lynx --version' or 'dpkg -l | grep lynx' (Debian) or 'rpm -qa | grep lynx' (Fedora) to identify the installed version
    Affected if The version number returned is 2.8.9 or lower
  2. Confirm package source
    Identify if the installed package came from Debian 9/10, Fedora 33/34/35, or upstream Lynx Project by checking package manager metadata or build info
    Affected if The package originates from any of the listed affected distributions and versions
  3. Verify SNI exposure scenario
    When Lynx connects to an HTTPS URL containing embedded credentials (format: https://username:password@hostname/), these credentials appear in the TLS ClientHello SNI field
    Affected if You use Lynx to access HTTPS URLs with username:password@ syntax and can observe the SNI containing those credentials

You are affected if your installed Lynx version is 2.8.9 or lower AND you use URLs with embedded credentials (username:password@host) to access HTTPS sites, causing those credentials to leak into the TLS SNI field.

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
Upgrade available Upgrade to a release after 2.8.9
Interim mitigation

Upgrade to Lynx 2.9.0 or later which properly handles URI userinfo. As a temporary workaround, avoid embedding credentials in URLs when using Lynx.

Fix this in Debian Linux Scoped from the published advisory
  • Consultation1.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,400
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An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,240.

Scan for this in your stack

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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-2021-38165 in production — separate from our analysis above.

No notes yet

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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