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Fencer Intel
critical 9.8

CVE-2019-18805 in the critical feed json

An issue was discovered in net/ipv4/sysctl_net_ipv4.c in the Linux kernel before 5.0.11.

published 7y ago modified 4mo ago also EUVD-2019-8509

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
3.5%
EPSS 3.5% chance of exploitation in 30 days, percentile 89%
public exploits
0
none known

Summary

An issue was discovered in net/ipv4/sysctl_net_ipv4.c in the Linux kernel before 5.0.11. There is a net/ipv4/tcp_input.c signed integer overflow in tcp_ack_update_rtt() when userspace writes a very large integer to /proc/sys/net/ipv4/tcp_min_rtt_wlen, leading to a denial of service or possibly unspecified other impact, aka CID-19fad20d15a6.

Patch / fix

  • linux linux_kernel 4.4.180, 4.9.172, 4.14.115, 4.19.38, 5.0.11
  • linux Debian 14, Debian 13, Debian 12 5.2.6-1

debian advisories DEBIAN-CVE-2019-18805

  • linux Ubuntu 16.04 LTS 4.4.0-157.185
  • linux Ubuntu 18.04 LTS 4.15.0-60.67
  • linux-aws Ubuntu 16.04 LTS 4.4.0-1090.101
  • linux-aws Ubuntu 18.04 LTS 4.15.0-1047.49
  • linux-gcp Ubuntu 16.04 LTS 4.15.0-1041.43
  • linux-gcp Ubuntu 18.04 LTS 4.15.0-1042.45
  • linux-hwe Ubuntu 16.04 LTS 4.15.0-60.67~16.04.1
  • linux-hwe Ubuntu 18.04 LTS 5.0.0-23.24~18.04.1

ubuntu advisories UBUNTU-CVE-2019-18805

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-alt RHEL 7 4.14.0-115.18.1.el7a
  • perf RHEL 7 4.14.0-115.18.1.el7a
  • kernel RHEL 7 4.14.0-115.18.1.el7a
  • python-perf RHEL 7 4.14.0-115.18.1.el7a
  • kernel-tools RHEL 7 4.14.0-115.18.1.el7a
  • kernel-tools-libs RHEL 7 4.14.0-115.18.1.el7a
  • kernel-bootwrapper RHEL 7 4.14.0-115.18.1.el7a
  • kernel-abi-whitelists RHEL 7 4.14.0-115.18.1.el7a

red hat advisories RHSA-2020:0740RHSA-2020:1567RHSA-2020:1769

  • kernel-azure SLES for SAP 12 SP5, SLES 12 SP5 4.12.14-16.7.1
  • kernel-syms-azure SLES for SAP 12 SP5, SLES 12 SP5 4.12.14-16.7.1
  • kernel-source-azure SLES for SAP 12 SP5, SLES 12 SP5 4.12.14-16.7.1
  • kernel-syms SLE Module for Development Tools 15 4.12.14-150.47.1
  • kernel-source SLE Module for Development Tools 15, SLE Module for Basesystem 15 4.12.14-150.47.1
  • kernel-default SLE Workstation Extension 15, SLE Module for Legacy 15, SLE Module for Basesystem 15 +2 more 4.12.14-150.47.1
  • kernel-vanilla SLE Module for Development Tools 15 4.12.14-150.47.1
  • kernel-zfcpdump SLE Module for Basesystem 15 4.12.14-150.47.1

suse advisories SUSE-SU-2020:0093-1SUSE-SU-2019:3381-1SUSE-SU-2019:3379-1SUSE-SU-2019:3372-1SUSE-SU-2019:3371-1SUSE-SU-2019:3317-1

  • kernel-syms openSUSE Leap 15.1 4.12.14-lp151.28.32.1
  • kernel-obs-qa openSUSE Leap 15.1 4.12.14-lp151.28.32.1
  • kernel-source openSUSE Leap 15.1 4.12.14-lp151.28.32.1
  • kernel-default openSUSE Leap 15.1 4.12.14-lp151.28.32.1
  • kernel-vanilla openSUSE Leap 15.1 4.12.14-lp151.28.32.1
  • kernel-kvmsmall openSUSE Leap 15.1 4.12.14-lp151.28.32.1
  • kernel-obs-build openSUSE Leap 15.1 4.12.14-lp151.28.32.1
  • kernel-syms openSUSE Leap 15.0 4.12.14-lp150.12.82.1

opensuse advisories openSUSE-SU-2019:2507-1openSUSE-SU-2019:2503-1

Is CVE-2019-18805 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

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-2019-18805 updated cvss 7.3

kernel: integer overflow in tcp_ack_update_rtt in net/ipv4/tcp_input.c

  • Red Hat CodeReady Linux Builder (v. 8) kernel-debuginfo-common-x86_64 4.18.0-193.el8, kernel-debuginfo-common-aarch64 4.18.0-193.el8, kernel-debuginfo-common-ppc64le 4.18.0-193.el8 Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-193.el8, kernel 4.18.0-193.el8, bpftool 4.18.0-193.el8, kernel-core 4.18.0-193.el8, kernel-tools 4.18.0-193.el8, python3-perf 4.18.0-193.el8, +15 more
    fixed: vendor fix RHSA-2020:1769
  • Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server (v. 7) perf 4.14.0-115.18.1.el7a, kernel 4.14.0-115.18.1.el7a, kernel-alt 4.14.0-115.18.1.el7a, python-perf 4.14.0-115.18.1.el7a, kernel-tools 4.14.0-115.18.1.el7a, kernel-tools-libs 4.14.0-115.18.1.el7a, +3 more Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server Optional (v. 7) kernel-debuginfo-common-ppc64le 4.14.0-115.18.1.el7a
    fixed: vendor fix RHSA-2020:0740
  • Red Hat Enterprise Linux Real Time (v. 8) kernel-rt 4.18.0-193.rt13.51.el8, kernel-rt-core 4.18.0-193.rt13.51.el8, kernel-rt-modules 4.18.0-193.rt13.51.el8, kernel-rt-debug-core 4.18.0-193.rt13.51.el8, kernel-rt-debug-modules 4.18.0-193.rt13.51.el8, kernel-rt-modules-extra 4.18.0-193.rt13.51.el8, +2 more Red Hat Enterprise Linux Real Time for NFV (v. 8) kernel-rt 4.18.0-193.rt13.51.el8, kernel-rt-kvm 4.18.0-193.rt13.51.el8, kernel-rt-core 4.18.0-193.rt13.51.el8, kernel-rt-modules 4.18.0-193.rt13.51.el8, kernel-rt-debug-kvm 4.18.0-193.rt13.51.el8, kernel-rt-debug-core 4.18.0-193.rt13.51.el8, +4 more
    fixed: vendor fix RHSA-2020:1567
  • Red Hat Enterprise Linux 5 kernel Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise MRG 2 kernel-rt, mrg-rt-release, kernel-rt-trace, kernel-rt-vanilla, kernel-rt-firmware
    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

3.47% chance of exploitation in the next 30 days, higher than 89% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P

Classification

Weakness
  • CWE-190 Integer Overflow or Wraparound
Technology feeds

References

Sources

Fencer Intel 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.