How severe is CVE-2016-1546?

CVE-2016-1546 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2016-1546 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 15% (96th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2016-1546?

CVE-2016-1546 primarily affects Apache Http Server. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2016-1546?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2016-1546 published?

CVE-2016-1546 was published on 2016-07-06 and last updated on 2026-06-17.

CVE-2016-1546

CVE-2016-1546 is a medium-severity vulnerability in Apache Http Server with a CVSS 3.x base score of 5.9. Its EPSS exploit-prediction score of 15% places it in the 96th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-399.

Key facts

Severity: Medium (CVSS 3.x base score 5.9)
CVSS v2: 4.3
EPSS exploit prediction: 15% (96th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-399
Affected product: Apache Http Server
Published: 2016-07-06
Last modified: 2026-06-17

Description

The Apache HTTP Server 2.4.17 and 2.4.18, when mod_http2 is enabled, does not limit the number of simultaneous stream workers for a single HTTP/2 connection, which allows remote attackers to cause a denial of service (stream-processing outage) via modified flow-control windows.

Frequently asked questions

What is CVE-2016-1546?: The Apache HTTP Server 2.4.17 and 2.4.18, when mod_http2 is enabled, does not limit the number of simultaneous stream workers for a single HTTP/2 connection, which allows remote attackers to cause a denial of service (stream-processing outage) via modified flow-control windows.
How severe is CVE-2016-1546?: CVE-2016-1546 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2016-1546 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 15% (96th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2016-1546?: CVE-2016-1546 primarily affects Apache Http Server. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2016-1546?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2016-1546 published?: CVE-2016-1546 was published on 2016-07-06 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:a:apache:http_server:2.4.17:*:*:*:*:*:*:*
cpe:2.3:a:apache:http_server:2.4.18:*:*:*:*:*:*:*

More vulnerabilities in Apache Http Server

CVE-2010-0425 — Critical (CVSS 10.0): modules/arch/win32/mod_isapi.c in mod_isapi in the Apache HTTP Server 2.0.37 through 2.0.63, 2.2.0 through 2.2.14, and…
CVE-2005-2700 — Critical (CVSS 10.0): ssl_engine_kernel.c in mod_ssl before 2.8.24, when using "SSLVerifyClient optional" in the global virtual host…
CVE-2004-0492 — Critical (CVSS 10.0): Heap-based buffer overflow in proxy_util.c for mod_proxy in Apache 1.3.25 to 1.3.31 allows remote attackers to cause a…
CVE-2003-0789 — Critical (CVSS 10.0): mod_cgid in Apache before 2.0.48, when using a threaded MPM, does not properly handle CGI redirect paths, which could…
CVE-1999-1293 — Critical (CVSS 10.0): mod_proxy in Apache 1.2.5 and earlier allows remote attackers to cause a denial of service via malformed FTP commands,…
CVE-1999-0926 — Critical (CVSS 10.0): Apache allows remote attackers to conduct a denial of service via a large number of MIME headers.

All CVEs affecting Apache Http Server →

Other CWE-399 (Resource Management Errors) vulnerabilities

CVE-2015-8104 — Critical (CVSS 10.0): The KVM subsystem in the Linux kernel through 4.2.6, and Xen 4.3.x through 4.6.x, allows guest OS users to cause a…
CVE-2015-0339 — Critical (CVSS 10.0): Adobe Flash Player before 13.0.0.277 and 14.x through 17.x before 17.0.0.134 on Windows and OS X and before…
CVE-2015-0335 — Critical (CVSS 10.0): Adobe Flash Player before 13.0.0.277 and 14.x through 17.x before 17.0.0.134 on Windows and OS X and before…
CVE-2015-0333 — Critical (CVSS 10.0): Adobe Flash Player before 13.0.0.277 and 14.x through 17.x before 17.0.0.134 on Windows and OS X and before…
CVE-2014-4121 — Critical (CVSS 10.0): Microsoft .NET Framework 2.0 SP2, 3.5, 3.5.1, 4, 4.5, 4.5.1, and 4.5.2 does not properly parse internationalized…
CVE-2014-0560 — Critical (CVSS 10.0): Use-after-free vulnerability in Adobe Reader and Acrobat 10.x before 10.1.12 and 11.x before 11.0.09 on Windows and OS…

Browse all CWE-399 (Resource Management Errors) vulnerabilities →

Threat intelligence

Threat-intel indicators referencing this CVE:

45.120.115.150 (ipv4-addr)
45.118.144.36 (ipv4-addr)
183.87.217.222 (ipv4-addr)
176.31.40.175 (ipv4-addr)
167.99.148.102 (ipv4-addr)
103.154.77.48 (ipv4-addr)
165.227.238.235 (ipv4-addr)
213.202.230.81 (ipv4-addr)