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Fencer Vulns
high 7.5

CVE-2019-6477 json

TCP-pipelined queries can bypass tcp-clients limit

published 2019-11-26 6 y ago modified 2026-06-17 4 mo ago also EUVD-2019-16037

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
4.1%
EPSS 4.1% chance of exploitation in 30 days, percentile 90%
public exploits
0
none known

Summary

With pipelining enabled each incoming query on a TCP connection requires a similar resource allocation to a query received via UDP or via TCP without pipelining enabled. A client using a TCP-pipelined connection to a server could consume more resources than the server has been provisioned to handle. When a TCP connection with a large number of pipelined queries is closed, the load on the server releasing these multiple resources can cause it to become unresponsive, even for queries that can be answered authoritatively or from cache. (This is most likely to be perceived as an intermittent server problem).

Patch / fix

  • bind9 Debian 14, Debian 13, Debian 12 1:9.11.14+dfsg-1

debian advisories DEBIAN-CVE-2019-6477

  • bind9 Ubuntu 18.04 LTS 1:9.11.3+dfsg-1ubuntu1.11

ubuntu advisories UBUNTU-CVE-2019-6477

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • bind RHEL 8 32:9.11.13-3.el8
  • bind-sdb RHEL 8 32:9.11.13-3.el8
  • bind-libs RHEL 8 32:9.11.13-3.el8
  • bind-utils RHEL 8 32:9.11.13-3.el8
  • bind-chroot RHEL 8 32:9.11.13-3.el8
  • bind-pkcs11 RHEL 8 32:9.11.13-3.el8
  • bind-license RHEL 8 32:9.11.13-3.el8
  • python3-bind RHEL 8 32:9.11.13-3.el8

red hat advisories RHSA-2020:1845RHSA-2020:1061

  • bind SLES for SAP 15, SLES 15-LTSS, SLE Module for Server Applications 15 SP2 +5 more 9.16.6-12.32.1
  • sysuser-tools SLES for SAP 15, SLES 15-LTSS, SLE Module for Development Tools 15 SP2 +4 more 2.0-4.2.8

suse advisories SUSE-SU-2020:2914-1

  • bind openSUSE Tumbleweed 9.16.20-1.4
  • bind openSUSE Leap 15.1 9.16.6-lp151.11.9.1
  • libuv openSUSE Leap 15.1 1.18.0-lp151.3.3.1
  • sysuser-tools openSUSE Leap 15.1 2.0-lp151.4.3.1
  • bind openSUSE Leap 15.2 9.16.6-lp152.14.3.1
  • libuv openSUSE Leap 15.2 1.18.0-lp152.4.3.1
  • sysuser-tools openSUSE Leap 15.2 2.0-lp152.5.3.1

opensuse advisories openSUSE-SU-2024:10650-1openSUSE-SU-2020:1701-1openSUSE-SU-2020:1699-1

  • bind Alpine 3.24, Alpine 3.23, Alpine 3.22 +12 more 9.14.8-r0

alpine advisories ALPINE-CVE-2019-6477

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2019-6477 updated cvss 7.5

bind: TCP Pipelining doesn't limit TCP clients on a single connection

  • Red Hat Enterprise Linux AppStream (v. 8) bind 9.11.13-3.el8, bind-sdb 9.11.13-3.el8, bind-libs 9.11.13-3.el8, bind-utils 9.11.13-3.el8, bind-chroot 9.11.13-3.el8, bind-pkcs11 9.11.13-3.el8, +6 more Red Hat Enterprise Linux BaseOS (v. 8) bind 9.11.13-3.el8, bind-export-libs 9.11.13-3.el8
    fixed: vendor fix RHSA-2020:1845
  • Red Hat Enterprise Linux Client (v. 7) bind 9.11.4-16.P2.el7, bind-libs 9.11.4-16.P2.el7, bind-utils 9.11.4-16.P2.el7, bind-license 9.11.4-16.P2.el7, bind-libs-lite 9.11.4-16.P2.el7, bind-export-libs 9.11.4-16.P2.el7 Red Hat Enterprise Linux Client Optional (v. 7) bind 9.11.4-16.P2.el7, bind-sdb 9.11.4-16.P2.el7, bind-chroot 9.11.4-16.P2.el7, bind-pkcs11 9.11.4-16.P2.el7, bind-sdb-chroot 9.11.4-16.P2.el7, bind-pkcs11-libs 9.11.4-16.P2.el7, +1 more Red Hat Enterprise Linux ComputeNode (v. 7) bind 9.11.4-16.P2.el7, bind-libs 9.11.4-16.P2.el7, bind-utils 9.11.4-16.P2.el7, bind-license 9.11.4-16.P2.el7, bind-libs-lite 9.11.4-16.P2.el7, bind-export-libs 9.11.4-16.P2.el7 Red Hat Enterprise Linux ComputeNode Optional (v. 7) bind 9.11.4-16.P2.el7, bind-sdb 9.11.4-16.P2.el7, bind-chroot 9.11.4-16.P2.el7, bind-pkcs11 9.11.4-16.P2.el7, bind-sdb-chroot 9.11.4-16.P2.el7, bind-pkcs11-libs 9.11.4-16.P2.el7, +1 more Red Hat Enterprise Linux Server (v. 7) bind 9.11.4-16.P2.el7, bind-libs 9.11.4-16.P2.el7, bind-utils 9.11.4-16.P2.el7, bind-chroot 9.11.4-16.P2.el7, bind-pkcs11 9.11.4-16.P2.el7, bind-license 9.11.4-16.P2.el7, +4 more Red Hat Enterprise Linux Server Optional (v. 7) bind-sdb 9.11.4-16.P2.el7, bind-sdb-chroot 9.11.4-16.P2.el7
    +2 more products
    Red Hat Enterprise Linux Workstation (v. 7) bind 9.11.4-16.P2.el7, bind-libs 9.11.4-16.P2.el7, bind-utils 9.11.4-16.P2.el7, bind-chroot 9.11.4-16.P2.el7, bind-pkcs11 9.11.4-16.P2.el7, bind-license 9.11.4-16.P2.el7, +4 more Red Hat Enterprise Linux Workstation Optional (v. 7) bind-sdb 9.11.4-16.P2.el7, bind-sdb-chroot 9.11.4-16.P2.el7
    fixed: vendor fix RHSA-2020:1061
  • Red Hat Enterprise Linux 5 bind, bind97 Red Hat Enterprise Linux 6 bind, bind-sdb, bind-libs, bind-utils, bind-chroot
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

4.13% chance of exploitation in the next 30 days, higher than 90% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P

Affected products

  • ISC BIND9

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.