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Debian LinuxOperating system · Debian

CVE-2021-35063

HIGH · 7.5 CVSS v3.1 Published 2021-07-22
Fix available
A fix is available. Upgrade to 5.0.7 / 6.0.3 or later.
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
Suricata before 5.0.7 and 6.x before 6.0.3 has a "critical evasion."

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

Suricata before 5.0.7 and 6.x before 6.0.3 contains an evasion vulnerability that allows attackers to bypass detection mechanisms, potentially letting malicious network traffic pass through the IDS undetected.

MitigationUpdate Suricata to version 5.0.7 or 6.0.3 or later to patch the evasion vulnerability.

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:= 34= 35
SuricataApplication
Affected:< 5.0.7>= 6.0.0, < 6.0.3

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
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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. Confirm Suricata is installed
    Run 'which suricata' on Linux or check your system's package manager for the suricata package
    Affected if Suricata is not found on the system, this CVE does not apply
  2. Identify installed Suricata version
    Run 'suricata --version' to display the installed version number
    Affected if The command fails or shows an unknown version, the specific version cannot be verified against affected ranges
  3. Compare version against affected ranges
    Check if the installed version falls into < 5.0.7 or >= 6.0.0 to < 6.0.3 by comparing the version number from step 2
    Affected if Version is less than 5.0.7 OR version is 6.0.0, 6.0.1, or 6.0.2, then the installation is affected by this evasion vulnerability
  4. Check OS vendor package version (Debian/Fedora)
    On Debian run 'dpkg -l suricata' or 'apt show suricata'; on Fedora run 'rpm -qi suricata' or 'dnf info suricata'
    Affected if The packaged version matches Debian 9.0, 10.0, Fedora 34, or Fedora 35, these packages contain the vulnerable Suricata versions

A user is affected if Suricata is installed with a version lower than 5.0.7 or within the 6.0.0 to 6.0.3 range, as these versions contain the detection bypass vulnerability.

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 5.0.7 / 6.0.3 or later
Fixed in 5.0.76.0.3
Interim mitigation

Update Suricata to version 5.0.7 or 6.0.3 or later to patch the evasion vulnerability.

Fix this in Debian Linux Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,190
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,904.

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-2021-35063 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