CVE-2018-1303

CVE-2018-1303 is a high-severity vulnerability in Apache Http Server with a CVSS 3.x base score of 7.5. Its EPSS exploit-prediction score of 71% places it in the 99th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-125.

Key facts

• Severity: High (CVSS 3.x base score 7.5)
• CVSS v2: 5.0
• EPSS exploit prediction: 71% (99th percentile)
• Actively exploited: Not listed in CISA KEV
• Weakness: CWE-125
• Affected product: Apache Http Server
• Published: 2018-03-26
• Last modified: 2026-06-17

Description

A specially crafted HTTP request header could have crashed the Apache HTTP Server prior to version 2.4.30 due to an out of bound read while preparing data to be cached in shared memory. It could be used as a Denial of Service attack against users of mod_cache_socache. The vulnerability is considered as low risk since mod_cache_socache is not widely used, mod_cache_disk is not concerned by this vulnerability.

Frequently asked questions

What is CVE-2018-1303?

A specially crafted HTTP request header could have crashed the Apache HTTP Server prior to version 2.4.30 due to an out of bound read while preparing data to be cached in shared memory. It could be used as a Denial of Service attack against users of mod_cache_socache. The vulnerability is considered as low risk since mod_cache_socache is not widely used, mod_cache_disk is not concerned by this vulnerability.

How severe is CVE-2018-1303?

CVE-2018-1303 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-2018-1303 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 71% (99th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2018-1303?

CVE-2018-1303 primarily affects Apache Http Server. In total, 11 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2018-1303?

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-2018-1303 published?

CVE-2018-1303 was published on 2018-03-26 and last updated on 2026-06-17.

References

• http://www.openwall.com/lists/oss-security/2018/03/24/3
• http://www.securityfocus.com/bid/103522
• http://www.securitytracker.com/id/1040572
• https://access.redhat.com/errata/RHSA-2018:3558
• https://access.redhat.com/errata/RHSA-2019:0366
• https://access.redhat.com/errata/RHSA-2019:0367
• https://httpd.apache.org/security/vulnerabilities_24.html
• https://lists.apache.org/thread.html/56c2e7cc9deb1c12a843d0dc251ea7fd3e7e80293cde02fcd65286ba%40%3Ccvs.httpd.apache.org%3E
• https://lists.apache.org/thread.html/84a3714f0878781f6ed84473d1a503d2cc382277e100450209231830%40%3Ccvs.httpd.apache.org%3E
• https://lists.apache.org/thread.html/r06f0d87ebb6d59ed8379633f36f72f5b1f79cadfda72ede0830b42cf%40%3Ccvs.httpd.apache.org%3E
• https://lists.apache.org/thread.html/r15f9aa4427581a1aecb4063f1b4b983511ae1c9935e2a0a6876dad3c%40%3Ccvs.httpd.apache.org%3E
• https://lists.apache.org/thread.html/r76142b8c5119df2178be7c2dba88fde552eedeec37ea993dfce68d1d%40%3Ccvs.httpd.apache.org%3E
• https://lists.apache.org/thread.html/r9f93cf6dde308d42a9c807784e8102600d0397f5f834890708bf6920%40%3Ccvs.httpd.apache.org%3E
• https://lists.apache.org/thread.html/rc998b18880df98bafaade071346690c2bc1444adaa1a1ea464b93f0a%40%3Ccvs.httpd.apache.org%3E
• https://lists.apache.org/thread.html/rd18c3c43602e66f9cdcf09f1de233804975b9572b0456cc582390b6f%40%3Ccvs.httpd.apache.org%3E
• https://lists.apache.org/thread.html/re3d27b6250aa8548b8845d314bb8a350b3df326cacbbfdfe4d455234%40%3Ccvs.httpd.apache.org%3E
• https://lists.apache.org/thread.html/re473305a65b4db888e3556e4dae10c2a04ee89dcff2e26ecdbd860a9%40%3Ccvs.httpd.apache.org%3E
• https://lists.apache.org/thread.html/rf6449464fd8b7437704c55f88361b66f12d5b5f90bcce66af4be4ba9%40%3Ccvs.httpd.apache.org%3E
• https://lists.apache.org/thread.html/rfcf929bd33a6833e3f0c35eebdad70d5060665f9c4e17ea467c66770%40%3Ccvs.httpd.apache.org%3E
• https://security.netapp.com/advisory/ntap-20180601-0004/
• https://support.hpe.com/hpsc/doc/public/display?docLocale=en_US&docId=emr_na-hpesbux03909en_us
• https://usn.ubuntu.com/3627-1/
• https://usn.ubuntu.com/3627-2/
• https://www.debian.org/security/2018/dsa-4164
• https://www.tenable.com/security/tns-2019-09

Affected products (11)

• cpe:2.3:a:apache:http_server:*:*:*:*:*:*:*:*
• cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
• cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
• cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:lts:*:*:*
• cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*
• cpe:2.3:o:canonical:ubuntu_linux:17.10:*:*:*:*:*:*:*
• cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*
• cpe:2.3:a:netapp:santricity_cloud_connector:-:*:*:*:*:*:*:*
• cpe:2.3:a:netapp:storage_automation_store:-:*:*:*:*:*:*:*
• cpe:2.3:a:netapp:storagegrid:-:*:*:*:*:*:*:*
• cpe:2.3:o:netapp:clustered_data_ontap:-:*:*:*:*:*:*:*

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-125 (Out-of-bounds Read) vulnerabilities

• CVE-2026-24826 — Critical (CVSS 10.0): Out-of-bounds Write, Divide By Zero, NULL Pointer Dereference, Use of Uninitialized Resource, Out-of-bounds Read,…
• CVE-2024-22004 — Critical (CVSS 10.0): Due to length check, an attacker with privilege access on a Linux Nonsecure operating system can trigger a…
• CVE-2021-41556 — Critical (CVSS 10.0): sqclass.cpp in Squirrel through 2.2.5 and 3.x through 3.1 allows an out-of-bounds read (in the core interpreter) that…
• CVE-2021-21777 — Critical (CVSS 10.0): An information disclosure vulnerability exists in the Ethernet/IP UDP handler functionality of EIP Stack Group OpENer…
• CVE-2017-14451 — Critical (CVSS 10.0): An exploitable out-of-bounds read vulnerability exists in libevm (Ethereum Virtual Machine) of CPP-Ethereum. A…
• CVE-2013-0767 — Critical (CVSS 10.0): The nsSVGPathElement::GetPathLengthScale function in Mozilla Firefox before 18.0, Firefox ESR 10.x before 10.0.12 and…

Browse all CWE-125 (Out-of-bounds Read) vulnerabilities →

Threat intelligence

Threat-intel indicators referencing this CVE:

• 147.15.15.226 (ipv4-addr)
• 218.4.91.163 (ipv4-addr)
• 45.84.120.3 (ipv4-addr)
• 79.137.34.248 (ipv4-addr)
• 61.76.112.4 (ipv4-addr)
• 60.199.224.2 (ipv4-addr)
• 45.232.73.84 (ipv4-addr)
• 45.120.115.150 (ipv4-addr)