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.

Published: 2018-03-26 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2018-1303 is rated High Risk (66.3/100): CVSS High severity, with high exploitation likelihood (EPSS 34.55%, 97th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. EPSS rose +2.29% over the last day, indicating growing attacker interest. High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2018-1303

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-26 32.25% 34.55% +2.29%
2 2026-04-25 40.14% 32.25% -7.89%
3 2026-03-08 — 40.14% —

Full EPSS history (55 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2018-1303

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.0 HIGH
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2018-1303

OS Trackers for CVE-2018-1303

vendor priority summary link
alpine high CVE-2018-1303: 1 source package rows (apache2); 10 state rows across 10 repos (3.10-main, 3.11-main, 3.12-main, 3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 10, open 0. https://security.alpinelinux.org/vuln/CVE-2018-1303
debian not yet assigned CVE-2018-1303 not yet assigned priority: Debian including 1 source packages (apache2), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2018-1303
redhat medium — https://access.redhat.com/security/cve/CVE-2018-1303
suse high CVE-2018-1303 severity important: SUSE including 47 source package names (apache2, apache2-2.4.10-14.31.1, …), 119 product×package rows across 25 product lines (SUSE Liberty Linux 7, SUSE Linux Enterprise High Performance Computing 12 SP5, … (25 product lines)): Fixed 101, Known Not Affected 18. https://www.suse.com/security/cve/CVE-2018-1303/
ubuntu low CVE-2018-1303 low priority: Ubuntu including 1 source packages (apache2), 5 status rows across 5 suites (artful, bionic, trusty, upstream, xenial): released 5. https://ubuntu.com/security/CVE-2018-1303

Affected software / configurations for CVE-2018-1303

Vendor Product Version Raw CPE
apache http_server <= 2.4.29 cpe:2.3:a:apache:http_server:*:*:*:*:*:*:*:*
debian debian_linux 8.0 cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
debian debian_linux 9.0 cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
canonical ubuntu_linux 14.04 cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:lts:*:*:*
canonical ubuntu_linux 16.04 cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*
canonical ubuntu_linux 17.10 cpe:2.3:o:canonical:ubuntu_linux:17.10:*:*:*:*:*:*:*
canonical ubuntu_linux 18.04 cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*
netapp santricity_cloud_connector — cpe:2.3:a:netapp:santricity_cloud_connector:-:*:*:*:*:*:*:*
netapp storage_automation_store — cpe:2.3:a:netapp:storage_automation_store:-:*:*:*:*:*:*:*
netapp storagegrid — cpe:2.3:a:netapp:storagegrid:-:*:*:*:*:*:*:*
netapp clustered_data_ontap — cpe:2.3:o:netapp:clustered_data_ontap:-:*:*:*:*:*:*:*

References for CVE-2018-1303

URL Tags
http://www.openwall.com/lists/oss-security/2018/03/24/3 Mailing List Third Party Advisory
http://www.securityfocus.com/bid/103522 Third Party Advisory VDB Entry
http://www.securitytracker.com/id/1040572 Third Party Advisory VDB Entry
https://access.redhat.com/errata/RHSA-2018:3558 Third Party Advisory
https://access.redhat.com/errata/RHSA-2019:0366 Third Party Advisory
https://access.redhat.com/errata/RHSA-2019:0367 Third Party Advisory
https://httpd.apache.org/security/vulnerabilities_24.html Vendor Advisory
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/ Third Party Advisory
https://support.hpe.com/hpsc/doc/public/display?docLocale=en_US&docId=emr_na-hpesbux03909en_us Third Party Advisory
https://usn.ubuntu.com/3627-1/ Third Party Advisory
https://usn.ubuntu.com/3627-2/ Third Party Advisory
https://www.debian.org/security/2018/dsa-4164 Third Party Advisory
https://www.tenable.com/security/tns-2019-09
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