How severe is CVE-2018-16843?

CVE-2018-16843 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2018-16843 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 47% (99th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2018-16843?

CVE-2018-16843 primarily affects F5 Nginx. In total, 8 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2018-16843?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2018-16843 published?

CVE-2018-16843 was published on 2018-11-07 and last updated on 2026-06-17.

CVE-2018-16843

CVE-2018-16843 is a high-severity vulnerability in F5 Nginx with a CVSS 3.x base score of 7.5. Its EPSS exploit-prediction score of 47% places it in the 99th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-400.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 7.8
EPSS exploit prediction: 47% (99th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-400
Affected product: F5 Nginx
Published: 2018-11-07
Last modified: 2026-06-17

Description

nginx before versions 1.15.6 and 1.14.1 has a vulnerability in the implementation of HTTP/2 that can allow for excessive memory consumption. This issue affects nginx compiled with the ngx_http_v2_module (not compiled by default) if the 'http2' option of the 'listen' directive is used in a configuration file.

Frequently asked questions

What is CVE-2018-16843?: nginx before versions 1.15.6 and 1.14.1 has a vulnerability in the implementation of HTTP/2 that can allow for excessive memory consumption. This issue affects nginx compiled with the ngx_http_v2_module (not compiled by default) if the 'http2' option of the 'listen' directive is used in a configuration file.
How severe is CVE-2018-16843?: CVE-2018-16843 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2018-16843 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 47% (99th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2018-16843?: CVE-2018-16843 primarily affects F5 Nginx. In total, 8 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2018-16843?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2018-16843 published?: CVE-2018-16843 was published on 2018-11-07 and last updated on 2026-06-17.

References

Affected products (8)

cpe:2.3:a:f5:nginx:*:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:esm:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:18.10:*:*:*:*:*:*:*
cpe:2.3:o:opensuse:leap:15.1:*:*:*:*:*:*:*
cpe:2.3:a:apple:xcode:*:*:*:*:*:*:*:*

More vulnerabilities in F5 Nginx

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Other CWE-400 (Uncontrolled Resource Consumption) vulnerabilities

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CVE-2025-61303 — Critical (CVSS 9.8): Hatching Triage Sandbox Windows 10 build 2004 (2025-08-14) and Windows 10 LTSC 2021(2025-08-14) contains a…
CVE-2025-43193 — Critical (CVSS 9.8): The issue was addressed with improved memory handling. This issue is fixed in macOS Sequoia 15.6, macOS Sonoma 14.7.7,…
CVE-2025-24269 — Critical (CVSS 9.8): The issue was addressed with improved memory handling. This issue is fixed in macOS Sequoia 15.4. An app may be able to…
CVE-2025-24264 — Critical (CVSS 9.8): The issue was addressed with improved memory handling. This issue is fixed in Safari 18.4, iOS 18.4 and iPadOS 18.4,…
CVE-2025-24260 — Critical (CVSS 9.8): The issue was addressed with improved memory handling. This issue is fixed in macOS Sequoia 15.4, macOS Sonoma 14.7.5,…

Browse all CWE-400 (Uncontrolled Resource Consumption) vulnerabilities →

Threat intelligence

Threat-intel indicators referencing this CVE:

114.67.252.10 (ipv4-addr)
203.193.147.75 (ipv4-addr)
42.200.66.164 (ipv4-addr)
24.122.136.94 (ipv4-addr)
180.76.98.88 (ipv4-addr)
139.59.59.165 (ipv4-addr)
135.129.128.247 (ipv4-addr)
211.253.31.30 (ipv4-addr)