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TcpdumpApplication

CVE-2016-7993

CRITICAL · 9.8 CVSS v3.0 Published 2017-01-28
Fix available
A fix is available. Upgrade to after 4.8.1 or later.
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
A bug in util-print.c:relts_print() in tcpdump before 4.9.0 could cause a buffer overflow in multiple protocol parsers (DNS, DVMRP, HSRP, IGMP, lightweight resolver protocol, PIM).

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

A buffer overflow vulnerability exists in tcpdump before 4.9.0 in the relts_print() function in util-print.c. The flaw affects multiple protocol parsers including DNS, DVMRP, HSRP, IGMP, lightweight resolver protocol, and PIM, potentially allowing remote code execution when processing malicious network packets.

MitigationUpgrade tcpdump to version 4.9.0 or later. If immediate patching is not possible, restrict network packet capture access to trusted sources and disable packet parsing for affected protocols where not required.

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
TcpdumpApplication
Affected:<= 4.8.1

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:3.0/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. Identify tcpdump version
    Run 'tcpdump --version' or 'tcpdump -h' to display the version number
    Affected if The version displayed is 4.8.1 or earlier
  2. Confirm the tcpdump binary location
    Run 'which tcpdump' to locate the executable, then check its version as above
    Affected if The binary is present and reports version 4.8.1 or earlier
  3. Check if packet capture is active
    Run 'tcpdump -D' or 'tcpdump -i <interface> -c 1' to see available interfaces and confirm capture functionality is in use
    Affected if Packet capture is enabled and running on any interface
  4. Identify parsed protocols
    Review tcpdump command-line arguments or capture scripts for presence of protocol filters such as 'dns', 'dvmrp', 'hsrp', 'igmp', 'lwrp', or 'pim'
    Affected if Any of the affected protocols (DNS, DVMRP, HSRP, IGMP, lightweight resolver protocol, PIM) are being parsed or filtered
  5. Verify library dependencies
    Run 'ldd $(which tcpdump)' to check linked libraries that may affect tcpdump behavior
    Affected if Standard tcpdump libraries are present without custom patches

A system is affected if tcpdump version 4.8.1 or earlier is installed and packet capture with the vulnerable protocols (DNS, DVMRP, HSRP, IGMP, LWRP, PIM) is in use.

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
Upgrade available Upgrade to a release after 4.8.1
Interim mitigation

Upgrade tcpdump to version 4.9.0 or later. If immediate patching is not possible, restrict network packet capture access to trusted sources and disable packet parsing for affected protocols where not required.

Recommended fix High confidence

tcpdump 4.9.0 or later

  1. Check current tcpdump version with: tcpdump --version or dpkg -l tcpdump
  2. Update your package repository: sudo apt-get update (Debian/Ubuntu) or sudo yum check-update (RHEL/CentOS)
  3. Upgrade tcpdump: sudo apt-get install tcpdump (Debian/Ubuntu) or sudo yum update tcpdump (RHEL/CentOS)
  4. Verify the upgrade was successful by checking the version is 4.9.0 or later: tcpdump --version

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

Fix this in Tcpdump 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 the upgrade done

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

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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-2016-7993 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