CVE-2018-20103

An issue was discovered in dns.c in HAProxy through 1.8.14. In the case of a compressed pointer, a crafted packet can trigger infinite recursion by making the pointer point to itself, or create a long chain of valid pointers resulting in stack exhaustion.

Published: 2018-12-12 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2018-20103 is rated High Risk (67.5/100): CVSS High severity, with high exploitation likelihood (EPSS 6.59%, 93th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. EPSS rose +6.49% 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-2018-20103

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 2026-06-15 0.10% 6.59% +6.49%
2 2025-11-21 0.21% 0.10% -0.11%
3 2025-11-18 — 0.21% —

Full EPSS history (18 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2018-20103

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-2018-20103

OS Trackers for CVE-2018-20103

vendor priority summary link
debian not yet assigned CVE-2018-20103 not yet assigned priority: Debian including 1 source packages (haproxy), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2018-20103
redhat high — https://access.redhat.com/security/cve/CVE-2018-20103
suse high CVE-2018-20103 severity important: SUSE including 9 source package names (haproxy, haproxy-1.8.15~git0.6b6a350a-3.6.2, …), 20 product×package rows across 20 product lines (HPE Helion OpenStack 8, SUSE Linux Enterprise High Availability Extension 12, … (20 product lines)): Known Not Affected 12, Fixed 8. https://www.suse.com/security/cve/CVE-2018-20103/
ubuntu medium CVE-2018-20103 medium priority: Ubuntu including 1 source packages (haproxy), 5 status rows across 5 suites (bionic, cosmic, trusty, upstream, xenial): released 3, DNE 1, not-affected 1. https://ubuntu.com/security/CVE-2018-20103

Affected software / configurations for CVE-2018-20103

Vendor Product Version Raw CPE
haproxy haproxy <= 1.8.14 cpe:2.3:a:haproxy:haproxy:*:*:*:*:*:*:*:*
canonical ubuntu_linux 16.04 cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*
canonical ubuntu_linux 18.04 cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*
canonical ubuntu_linux 18.10 cpe:2.3:o:canonical:ubuntu_linux:18.10:*:*:*:*:*:*:*
redhat openshift_container_platform 3.11 cpe:2.3:a:redhat:openshift_container_platform:3.11:*:*:*:*:*:*:*

References for CVE-2018-20103

cvelogic Threat Intelligence