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HIGH

CVE-2018-5391

CVSS v3

7.5

HIGH

EPSS Score

32.4 %

exploit probability, as of 2026-10-20

CISA KEV

No

known exploited

Exploitation

—

SSVC status

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Affected and fixed versions

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Vendor advisories

  • CVE-2018-5391 Red Hat Product Security1,041 products fixed · 1 known affected

    kernel: IP fragments with random offsets allow a remote denial of service (FragmentSmack)

    kernel.src as a component of Red Hat Enterprise Linux 5

  • ICSA-20-105-05 CISA21 known affected

    Siemens RUGGEDCOM, SCALANCE, SIMATIC, SINEMA (Update B)

    Siemens RUGGEDCOM RM1224: All Versions < V6.1 · Siemens RUGGEDCOM ROX II: All versions < V2.13.3 · Siemens SCALANCE M-800 / S615: All Versions < V6.1

  • RHSA-2018:3590 Red Hat Product Security75 products fixed

    Red Hat Security Advisory: kernel security and bug fix update

  • RHSA-2018:3540 Red Hat Product Security111 products fixed

    Red Hat Security Advisory: kernel security, bug fix, and enhancement update

  • RHSA-2018:3586 Red Hat Product Security16 products fixed

    Red Hat Security Advisory: kernel-rt security and bug fix update

  • RHSA-2018:3459 Red Hat Product Security111 products fixed

    Red Hat Security Advisory: kernel security, bug fix, and enhancement update

9 more advisories

Full record on NVD

Description

The Linux kernel, versions 3.9+, is vulnerable to a denial of service attack with low rates of specially modified packets targeting IP fragment re-assembly. An attacker may cause a denial of service condition by sending specially crafted IP fragments. Various vulnerabilities in IP fragmentation have been discovered and fixed over the years. The current vulnerability (CVE-2018-5391) became exploitable in the Linux kernel with the increase of the IP fragment reassembly queue size.

Technical details

Published
2018-09-06

Frequently asked questions

What is CVE-2018-5391?

The Linux kernel, versions 3.9+, is vulnerable to a denial of service attack with low rates of specially modified packets targeting IP fragment re-assembly. An attacker may cause a denial of service condition by sending specially crafted IP fragments. Various vulnerabilities in IP fragmentation have been discovered and fixed over the years. The current vulnerability (CVE-2018-5391) became exploitable in the Linux kernel with the increase of the IP fragment reassembly queue size.

Is CVE-2018-5391 actively exploited?

Active exploitation of CVE-2018-5391 has not been confirmed. Its EPSS score was 32.4% on 2026-10-20, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2018-5391?

CVE-2018-5391 has a CVSS v3 base score of 7.5 (HIGH severity).

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