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Fencer Vulns
medium 4.8

CVE-2016-5696 json

net/ipv4/tcp_input.c in the Linux kernel before 4.7 does not properly determine the rate of challenge ACK segments, which makes it easier f…

published 2016-08-06 10 y ago modified 2026-06-17 4 mo ago also EUVD-2016-6639

cvss
4.8
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
14.5%
EPSS 14.5% chance of exploitation in 30 days, percentile 96%
public exploits
0
none known

Summary

net/ipv4/tcp_input.c in the Linux kernel before 4.7 does not properly determine the rate of challenge ACK segments, which makes it easier for remote attackers to hijack TCP sessions via a blind in-window attack.

Patch / fix

  • linux Debian 14, Debian 13, Debian 12 4.7.2-1

debian advisories DEBIAN-CVE-2016-5696

  • linux Ubuntu 14.04 LTS 3.13.0-95.142
  • linux Ubuntu 16.04 LTS 4.4.0-36.55
  • linux-raspi2 Ubuntu 16.04 LTS 4.4.0-1021.27
  • linux-lts-vivid Ubuntu 14.04 LTS 3.19.0-68.76~14.04.1
  • linux-lts-xenial Ubuntu 14.04 LTS 4.4.0-36.55~14.04.1
  • linux-snapdragon Ubuntu 16.04 LTS 4.4.0-1024.27

ubuntu advisories UBUNTU-CVE-2016-5696

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

  • kernel RHEL 7 3.10.0-327.28.3.el7
  • perf RHEL 7 3.10.0-327.28.3.el7
  • python-perf RHEL 7 3.10.0-327.28.3.el7
  • kernel-kdump RHEL 7 3.10.0-327.28.3.el7
  • kernel-tools RHEL 7 3.10.0-327.28.3.el7
  • kernel-tools-libs RHEL 7 3.10.0-327.28.3.el7
  • kernel-bootwrapper RHEL 7 3.10.0-327.28.3.el7
  • kernel-abi-whitelists RHEL 7 3.10.0-327.28.3.el7

red hat advisories RHSA-2016:1633RHSA-2016:1815RHSA-2016:1814RHSA-2016:1939RHSA-2016:1664RHSA-2016:1657

  • kernel-rt SLE Real Time 11 SP4 3.0.101.rt130-68.1
  • kernel-syms-rt SLE Real Time 11 SP4 3.0.101.rt130-68.1
  • kernel-rt_trace SLE Real Time 11 SP4 3.0.101.rt130-68.1
  • kernel-source-rt SLE Real Time 11 SP4 3.0.101.rt130-68.1
  • kernel-ec2 SLE Module for Public Cloud 12 3.12.61-52.66.1
  • kernel-ec2 SLES for SAP 11 SP4, SLES 11 SP4 3.0.101-94.1
  • kernel-pae SLES for SAP 11 SP4, SLES 11 SP4 3.0.101-94.1
  • kernel-xen SLES for SAP 11 SP4, SLES 11 SP4 3.0.101-94.1

suse advisories SUSE-SU-2017:1102-1SUSE-SU-2017:0471-1SUSE-SU-2017:0437-1SUSE-SU-2016:3304-1SUSE-SU-2016:3069-1SUSE-SU-2016:2976-1

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-2016-5696 updated cvss 4.8

kernel: challenge ACK counter information disclosure.

  • Red Hat Enterprise Linux Client (v. 7) perf 3.10.0-327.28.3.el7, kernel 3.10.0-327.28.3.el7, python-perf 3.10.0-327.28.3.el7, kernel-tools 3.10.0-327.28.3.el7, kernel-tools-libs 3.10.0-327.28.3.el7, kernel-abi-whitelists 3.10.0-327.28.3.el7, +1 more Red Hat Enterprise Linux Client Optional (v. 7) kernel-debuginfo-common-x86_64 3.10.0-327.28.3.el7 Red Hat Enterprise Linux ComputeNode (v. 7) perf 3.10.0-327.28.3.el7, kernel 3.10.0-327.28.3.el7, python-perf 3.10.0-327.28.3.el7, kernel-tools 3.10.0-327.28.3.el7, kernel-tools-libs 3.10.0-327.28.3.el7, kernel-abi-whitelists 3.10.0-327.28.3.el7, +1 more
    fixed: vendor fix RHSA-2016:1633
  • Red Hat Enterprise Linux ComputeNode EUS (v. 7.1) perf 3.10.0-229.40.1.el7, kernel 3.10.0-229.40.1.el7, kernel-tools 3.10.0-229.40.1.el7, kernel-tools-libs 3.10.0-229.40.1.el7, kernel-abi-whitelists 3.10.0-229.40.1.el7, kernel-debuginfo-common-x86_64 3.10.0-229.40.1.el7
    fixed: vendor fix RHSA-2016:1657
  • Red Hat Enterprise Linux ComputeNode Optional (v. 7) kernel-debuginfo-common-x86_64 3.10.0-327.28.3.el7
    fixed: vendor fix RHSA-2016:1633
  • Red Hat Enterprise Linux ComputeNode Optional EUS (v. 7.1) python-perf 3.10.0-229.40.1.el7, kernel-debuginfo-common-x86_64 3.10.0-229.40.1.el7
    fixed: vendor fix RHSA-2016:1657
  • Red Hat Enterprise Linux Desktop (v. 6) perf 2.6.32-642.4.2.el6, kernel 2.6.32-642.4.2.el6, kernel-firmware 2.6.32-642.4.2.el6, kernel-abi-whitelists 2.6.32-642.4.2.el6, kernel-debuginfo-common-i686 2.6.32-642.4.2.el6, kernel-debuginfo-common-x86_64 2.6.32-642.4.2.el6 Red Hat Enterprise Linux Desktop Optional (v. 6) python-perf 2.6.32-642.4.2.el6, kernel-debuginfo-common-i686 2.6.32-642.4.2.el6, kernel-debuginfo-common-x86_64 2.6.32-642.4.2.el6
    fixed: vendor fix RHSA-2016:1664
  • Red Hat Enterprise Linux for Real Time for NFV (v. 7) kernel-rt 3.10.0-327.28.3.rt56.235.el7, kernel-rt-kvm 3.10.0-327.28.3.rt56.235.el7, kernel-rt-trace 3.10.0-327.28.3.rt56.235.el7, kernel-rt-debug-kvm 3.10.0-327.28.3.rt56.235.el7, kernel-rt-trace-kvm 3.10.0-327.28.3.rt56.235.el7, kernel-rt-debuginfo-common-x86_64 3.10.0-327.28.3.rt56.235.el7
    fixed: vendor fix RHSA-2016:1632
  • Red Hat Enterprise Linux HPC Node (v. 6) perf 2.6.32-642.4.2.el6, kernel 2.6.32-642.4.2.el6, kernel-firmware 2.6.32-642.4.2.el6, kernel-abi-whitelists 2.6.32-642.4.2.el6, kernel-debuginfo-common-i686 2.6.32-642.4.2.el6, kernel-debuginfo-common-x86_64 2.6.32-642.4.2.el6
    fixed: vendor fix RHSA-2016:1664
  • Red Hat Enterprise Linux HPC Node EUS (v. 6.6) perf 2.6.32-504.52.1.el6, kernel 2.6.32-504.52.1.el6, kernel-firmware 2.6.32-504.52.1.el6, kernel-abi-whitelists 2.6.32-504.52.1.el6, kernel-debuginfo-common-i686 2.6.32-504.52.1.el6, kernel-debuginfo-common-x86_64 2.6.32-504.52.1.el6
    fixed: vendor fix RHSA-2016:1939
show 23 more
  • Red Hat Enterprise Linux HPC Node EUS (v. 6.7) perf 2.6.32-573.34.1.el6, kernel 2.6.32-573.34.1.el6, kernel-firmware 2.6.32-573.34.1.el6, kernel-abi-whitelists 2.6.32-573.34.1.el6, kernel-debuginfo-common-i686 2.6.32-573.34.1.el6, kernel-debuginfo-common-x86_64 2.6.32-573.34.1.el6
    fixed: vendor fix RHSA-2016:1815
  • Red Hat Enterprise Linux HPC Node Optional (v. 6) python-perf 2.6.32-642.4.2.el6, kernel-debuginfo-common-x86_64 2.6.32-642.4.2.el6
    fixed: vendor fix RHSA-2016:1664
  • Red Hat Enterprise Linux HPC Node Optional EUS (v. 6.6) python-perf 2.6.32-504.52.1.el6, kernel-debuginfo-common-x86_64 2.6.32-504.52.1.el6
    fixed: vendor fix RHSA-2016:1939
  • Red Hat Enterprise Linux HPC Node Optional EUS (v. 6.7) python-perf 2.6.32-573.34.1.el6, kernel-debuginfo-common-x86_64 2.6.32-573.34.1.el6
    fixed: vendor fix RHSA-2016:1815
  • Red Hat Enterprise Linux Realtime (v. 7) kernel-rt 3.10.0-327.28.3.rt56.235.el7, kernel-rt-trace 3.10.0-327.28.3.rt56.235.el7, kernel-rt-debuginfo-common-x86_64 3.10.0-327.28.3.rt56.235.el7
    fixed: vendor fix RHSA-2016:1632
  • Red Hat Enterprise Linux Server (v. 6) perf 2.6.32-642.4.2.el6, kernel 2.6.32-642.4.2.el6, kernel-kdump 2.6.32-642.4.2.el6, kernel-firmware 2.6.32-642.4.2.el6, kernel-bootwrapper 2.6.32-642.4.2.el6, kernel-abi-whitelists 2.6.32-642.4.2.el6, +4 more
    fixed: vendor fix RHSA-2016:1664
  • Red Hat Enterprise Linux Server (v. 7) perf 3.10.0-327.28.3.el7, kernel 3.10.0-327.28.3.el7, python-perf 3.10.0-327.28.3.el7, kernel-kdump 3.10.0-327.28.3.el7, kernel-tools 3.10.0-327.28.3.el7, kernel-tools-libs 3.10.0-327.28.3.el7, +6 more
    fixed: vendor fix RHSA-2016:1633
  • Red Hat Enterprise Linux Server AUS (v. 6.5) perf 2.6.32-431.73.2.el6, kernel 2.6.32-431.73.2.el6, kernel-firmware 2.6.32-431.73.2.el6, kernel-abi-whitelists 2.6.32-431.73.2.el6, kernel-debuginfo-common-x86_64 2.6.32-431.73.2.el6
    fixed: vendor fix RHSA-2016:1814
  • Red Hat Enterprise Linux Server EUS (v. 6.6) perf 2.6.32-504.52.1.el6, kernel 2.6.32-504.52.1.el6, kernel-kdump 2.6.32-504.52.1.el6, kernel-firmware 2.6.32-504.52.1.el6, kernel-bootwrapper 2.6.32-504.52.1.el6, kernel-abi-whitelists 2.6.32-504.52.1.el6, +4 more
    fixed: vendor fix RHSA-2016:1939
  • Red Hat Enterprise Linux Server EUS (v. 6.7) perf 2.6.32-573.34.1.el6, kernel 2.6.32-573.34.1.el6, kernel-kdump 2.6.32-573.34.1.el6, kernel-firmware 2.6.32-573.34.1.el6, kernel-bootwrapper 2.6.32-573.34.1.el6, kernel-abi-whitelists 2.6.32-573.34.1.el6, +4 more
    fixed: vendor fix RHSA-2016:1815
  • Red Hat Enterprise Linux Server EUS (v. 7.1) perf 3.10.0-229.40.1.el7, kernel 3.10.0-229.40.1.el7, perf 3.10.0-229.40.1.ael7b, kernel 3.10.0-229.40.1.ael7b, kernel-kdump 3.10.0-229.40.1.el7, kernel-tools 3.10.0-229.40.1.el7, +11 more
    fixed: vendor fix RHSA-2016:1657
  • Red Hat Enterprise Linux Server Optional (v. 6) python-perf 2.6.32-642.4.2.el6, kernel-debuginfo-common-i686 2.6.32-642.4.2.el6, kernel-debuginfo-common-ppc64 2.6.32-642.4.2.el6, kernel-debuginfo-common-s390x 2.6.32-642.4.2.el6, kernel-debuginfo-common-x86_64 2.6.32-642.4.2.el6
    fixed: vendor fix RHSA-2016:1664
  • Red Hat Enterprise Linux Server Optional (v. 7) kernel-debuginfo-common-ppc64 3.10.0-327.28.3.el7, kernel-debuginfo-common-x86_64 3.10.0-327.28.3.el7, kernel-debuginfo-common-ppc64le 3.10.0-327.28.3.el7
    fixed: vendor fix RHSA-2016:1633
  • Red Hat Enterprise Linux Server Optional AUS (v. 6.5) kernel 2.6.32-431.73.2.el6, python-perf 2.6.32-431.73.2.el6, kernel-debuginfo-common-x86_64 2.6.32-431.73.2.el6
    fixed: vendor fix RHSA-2016:1814
  • Red Hat Enterprise Linux Server Optional EUS (v. 6.6) python-perf 2.6.32-504.52.1.el6, kernel-debuginfo-common-i686 2.6.32-504.52.1.el6, kernel-debuginfo-common-ppc64 2.6.32-504.52.1.el6, kernel-debuginfo-common-s390x 2.6.32-504.52.1.el6, kernel-debuginfo-common-x86_64 2.6.32-504.52.1.el6
    fixed: vendor fix RHSA-2016:1939
  • Red Hat Enterprise Linux Server Optional EUS (v. 6.7) python-perf 2.6.32-573.34.1.el6, kernel-debuginfo-common-i686 2.6.32-573.34.1.el6, kernel-debuginfo-common-ppc64 2.6.32-573.34.1.el6, kernel-debuginfo-common-s390x 2.6.32-573.34.1.el6, kernel-debuginfo-common-x86_64 2.6.32-573.34.1.el6
    fixed: vendor fix RHSA-2016:1815
  • Red Hat Enterprise Linux Server Optional EUS (v. 7.1) python-perf 3.10.0-229.40.1.el7, python-perf 3.10.0-229.40.1.ael7b, kernel-debuginfo-common-ppc64 3.10.0-229.40.1.el7, kernel-debuginfo-common-s390x 3.10.0-229.40.1.el7, kernel-debuginfo-common-x86_64 3.10.0-229.40.1.el7, kernel-debuginfo-common-ppc64le 3.10.0-229.40.1.ael7b
    fixed: vendor fix RHSA-2016:1657
  • Red Hat Enterprise Linux Workstation (v. 6) perf 2.6.32-642.4.2.el6, kernel 2.6.32-642.4.2.el6, kernel-firmware 2.6.32-642.4.2.el6, kernel-abi-whitelists 2.6.32-642.4.2.el6, kernel-debuginfo-common-i686 2.6.32-642.4.2.el6, kernel-debuginfo-common-x86_64 2.6.32-642.4.2.el6
    fixed: vendor fix RHSA-2016:1664
  • Red Hat Enterprise Linux Workstation (v. 7) perf 3.10.0-327.28.3.el7, kernel 3.10.0-327.28.3.el7, python-perf 3.10.0-327.28.3.el7, kernel-tools 3.10.0-327.28.3.el7, kernel-tools-libs 3.10.0-327.28.3.el7, kernel-abi-whitelists 3.10.0-327.28.3.el7, +1 more
    fixed: vendor fix RHSA-2016:1633
  • Red Hat Enterprise Linux Workstation Optional (v. 6) python-perf 2.6.32-642.4.2.el6, kernel-debuginfo-common-i686 2.6.32-642.4.2.el6, kernel-debuginfo-common-x86_64 2.6.32-642.4.2.el6
    fixed: vendor fix RHSA-2016:1664
  • Red Hat Enterprise Linux Workstation Optional (v. 7) kernel-debuginfo-common-x86_64 3.10.0-327.28.3.el7
    fixed: vendor fix RHSA-2016:1633
  • Red Hat MRG Realtime for RHEL 6 Server v.2 kernel-rt 3.10.0-327.rt56.195.el6rt, kernel-rt-trace 3.10.0-327.rt56.195.el6rt, kernel-rt-vanilla 3.10.0-327.rt56.195.el6rt, kernel-rt-firmware 3.10.0-327.rt56.195.el6rt, kernel-rt-debuginfo-common-x86_64 3.10.0-327.rt56.195.el6rt
    fixed: vendor fix RHSA-2016:1631
  • Red Hat Enterprise Linux 4 kernel Red Hat Enterprise Linux 5 kernel
    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

14.51% chance of exploitation in the next 30 days, higher than 96% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/Gnoxter/mountain_goat referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.0 4.8 CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:L
NVD 2.0 5.8 AV:N/AC:M/Au:N/C:N/I:P/A:P

Classification

Weakness
  • CWE-200 Exposure of Sensitive Information to an Unauthorized Actor
Technology feeds

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.