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PatchSiren cyber security CVE debrief

CVE-2016-7939 Tcpdump CVE debrief

CVE-2016-7939 is a critical buffer overflow in tcpdump’s GRE parser code path (print-gre.c), affecting tcpdump versions through 4.8.1. The NVD CVSS 3.0 vector rates it as network-reachable, low-complexity, no-authentication, no-user-interaction, with high confidentiality, integrity, and availability impact. The practical defensive takeaway is straightforward: systems that process untrusted packet captures or live traffic with vulnerable tcpdump builds should be upgraded to a fixed release and treated as high priority.

Vendor
Tcpdump
Product
CVE-2016-7939
CVSS
CRITICAL 9.8
CISA KEV
Not listed in stored evidence
Original CVE published
2017-01-28
Original CVE updated
2026-05-13
Advisory published
2017-01-28
Advisory updated
2026-05-13

Who should care

Security teams, Linux and Unix package maintainers, incident response teams, and anyone using tcpdump to inspect untrusted packet captures or live network traffic should care most. Environments that rely on tcpdump for automation, forensic analysis, or monitoring should prioritize remediation because the flaw is in packet parsing logic.

Technical summary

NVD describes the issue as a GRE parser buffer overflow in tcpdump before 4.9.0, with the vulnerable code located in print-gre.c and affecting multiple functions. The affected CPE scope in NVD covers tcpdump versions up to and including 4.8.1. NVD assigns CWE-119 and a CVSS 3.0 score of 9.8 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H), indicating that malformed input reaching the parser can have severe consequences.

Defensive priority

Critical. The vulnerability is remotely reachable in the sense of parsing attacker-controlled network data or capture content, requires no privileges or user interaction, and is rated 9.8 by NVD. Remediation should be treated as urgent wherever vulnerable tcpdump versions are installed.

Recommended defensive actions

  • Upgrade tcpdump to a fixed release at or above 4.9.0.
  • Inventory systems and appliances that ship or bundle tcpdump, including distro packages.
  • Avoid processing untrusted packet captures on vulnerable versions until patched.
  • Prioritize patching hosts used for incident response, monitoring, and packet analysis.
  • Verify package updates through vendor advisories referenced by NVD, including Debian, Red Hat, and Gentoo notices.

Evidence notes

Primary evidence comes from the official NVD record and the CVE record linked by CVE.org. NVD describes the flaw as a GRE parser buffer overflow in tcpdump before 4.9.0 and maps it to tcpdump versions through 4.8.1. The NVD CVSS vector is CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. NVD also assigns CWE-119. Additional references in the CVE metadata point to Debian, Red Hat, and Gentoo advisories plus a SecurityFocus and SecurityTracker entry, supporting that the issue was broadly tracked by downstream vendors.

Official resources

The CVE was published on 2017-01-28T01:59:00.657Z. The NVD record was later modified on 2026-05-13T00:24:29.033Z. Use the published CVE date for disclosure timing; the later modified date reflects record updates, not original disclosure.