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CVE-2016-5417 Gnu CVE debrief

CVE-2016-5417 is a denial-of-service issue in GNU C Library (glibc) libresolv. The flaw is described as a memory leak in __res_vinit within IPv6 name server management code, where partial initialization of internal resolver data structures can leave allocated memory unreleased. On affected systems, repeated triggering can drive memory consumption high enough to impact availability. NVD lists the vulnerable glibc range as versions up to 2.23, and the CVSS vector reflects a network-reachable, no-authentication availability impact.

Vendor
Gnu
Product
CVE-2016-5417
CVSS
HIGH 7.5
CISA KEV
Not listed in stored evidence
Original CVE published
2017-02-17
Original CVE updated
2026-05-13
Advisory published
2017-02-17
Advisory updated
2026-05-13

Who should care

Organizations running GNU glibc on Linux or Unix-like systems should care, especially if their workloads rely on resolver functionality or operate network-facing services that may exercise DNS lookups. System administrators, distro maintainers, and platform teams should prioritize this if they still run glibc 2.23 or earlier, or if they consume vendor backports based on the affected resolver code.

Technical summary

The issue is in __res_vinit, part of libresolv’s IPv6 name server management logic. According to the NVD description, partial initialization of internal resolver data structures can produce a memory leak. The practical impact is remote denial of service through memory consumption rather than code execution or data corruption. NVD maps the weakness to CWE-399 and assigns CVSS 3.0 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Defensive priority

High priority for availability-sensitive environments. The vulnerability is network-reachable, requires no privileges or user interaction, and can affect memory use on exposed systems that rely on the affected resolver path.

Recommended defensive actions

  • Confirm the installed glibc version on all affected hosts and containers; treat glibc 2.23 and earlier as vulnerable per NVD.
  • Upgrade to glibc 2.24 or later, or apply the vendor backport/package update that includes the upstream fix.
  • Review distro advisories and upstream references tied to Sourceware bug 19257 and the glibc commit for the exact patched build in your distribution.
  • Prioritize systems that process high volumes of DNS lookups or provide long-running network services, since memory leaks are most operationally visible there.
  • Monitor resolver-heavy hosts for unusual memory growth and restart thresholds while patching is being rolled out.
  • Validate remediation in staging before broad deployment, especially where libc updates may affect other packages or container images.

Evidence notes

The NVD record provides the primary description, CVSS vector, weakness classification, and affected CPE criteria. It states that glibc versions through 2.23 are vulnerable and describes the issue as a memory leak in __res_vinit leading to remote DoS via memory consumption. Upstream corroboration is present in the Openwall oss-security thread, Sourceware bug 19257, the glibc commit diff, and the libc-alpha release notes reference.

Official resources

The CVE was published in NVD on 2017-02-17, while the public discussion reference in oss-security dates to 2016-08-02. Use the CVE publication date for record timing and the 2016 reference for initial public disclosure context.