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CVE-2023-6516

Exploitation: none CVSS 7.5 HIGH

CVSS base score: 7.5 (High) vendor CNA · v3.1

Score assigned by the vendor's own CVE Numbering Authority (CNA); CISA's Vulnrichment program adds a score only when the CNA omits one.

Vendor: ISC   Product: BIND 9

Description

To keep its cache database efficient, `named` running as a recursive resolver occasionally attempts to clean up the database. It uses several methods, including some that are asynchronous: a small chunk of memory pointing to the cache element that can be cleaned up is first allocated and then queued for later processing. It was discovered that if the resolver is continuously processing query patterns triggering this type of cache-database maintenance, `named` may not be able to handle the cleanup events in a timely manner. This in turn enables the list of queued cleanup events to grow infinitely large over time, allowing the configured `max-cache-size` limit to be significantly exceeded. This issue affects BIND 9 versions 9.16.0 through 9.16.45 and 9.16.8-S1 through 9.16.45-S1.

Lifecycle Timeline

Each milestone comes from a different source, so gaps between them are gaps in what those sources publish, not evidence that nothing happened. EPSS history for this CVE holds 148 points from 2024-02-17, tracked daily from 2026-09-09; earlier points are weekly, which dates a spike to within a week. Peak probability 2.5% on 2025-03-29.

Published Applicability

Red Hat CSAF/VEX 0 affected · 580 fixed · 47 not affected
OSV.dev (incl. GHSA) 2 affected · 0 fixed · 0 not affected
CVE List v5 (CNA container) 2 affected · 0 fixed · 0 not affected
CVE List v5 (ADP/Vulnrichment) 2 affected · 0 fixed · 0 not affected

Check whether a specific version is affected →

What each source publishes about which product versions carry this vulnerability, kept as written rather than merged. Absence here means no source has published applicability data, not that nothing is affected.

Research & News Coverage

No mentions found in monitored research blogs or news feeds.

Detection & Exploitation

Exploit / Pen Test
none published
Network IDS/IPS
none published
Host / SIEM
none published

Coverage across public collections only: Nuclei and OpenVAS NVT (scan); Snort and Suricata ET Open (network); Sigma and YARA (host/SIEM); Metasploit, Exploit-DB and public GitHub repositories (exploit). Absence here means nothing public was found, not that detection is impossible.
GitHub PoC repositories are collected automatically by PoC-in-GitHub (CC0) and are not vetted: some are fakes and some are malware. Treat them as evidence that code was published, not as code to run.
OpenVAS coverage derives from the Greenbone Community Feed, made available under the Open Database License (ODbL) v1.0; its individual Vulnerability Tests are licensed GNU GPL v2.

Distribution Status

Debian · bind9 bookworm 1:9.17.19-1 trixie 1:9.17.19-1 forky 1:9.17.19-1 sid 1:9.17.19-1 scope: local

Where the distribution has shipped a fix, and in which version. Green means the release has resolved it, amber that it is still open. Data from the Debian Security Tracker, used under Debian's MIT / GPLv2+ terms. Debian is upstream of several other distributions, so a fix here often precedes theirs.

CISA Assessment (Vulnrichment / SSVC)

none
yes
partial
—
7.5 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE-789 — Memory Allocation with Excessive Size Value
2024-06-28

D3FEND Countermeasures

Defensive techniques inferred by MITRE D3FEND from the underlying weakness (CWE-789) — general hardening and detection guidance for this weakness class, not a vendor patch for this specific CVE.

Listed By

SourceDateRecord
CISA Vulnrichment 2024-06-28 source record →

Referenced in Advisories

DateAdvisoryIssuer
2024-02-13 ISC Releases Security Advisories for BIND 9 CISA

Weaponization Timeline — Offensive & Testing Tools

No exploit-tool sightings recorded for this CVE.

Evidence tiers are explained on the About page — a merged Metasploit module is far stronger evidence than a distro package mention.

External References