CVE-2015-6525

Multiple integer overflows in the evbuffer API in Libevent 2.0.x before 2.0.22 and 2.1.x before 2.1.5-beta allow context-dependent attackers to cause a denial of service or possibly have other unspecified impact via "insanely large inputs" to the (1) evbuffer_add, (2) evbuffer_prepend, (3) evbuffer_expand, (4) exbuffer_reserve_space, or (5) evbuffer_read function, which triggers a heap-based buffer overflow or an infinite loop. NOTE: this identifier was SPLIT from CVE-2014-6272 per ADT3 due to different affected versions.

Published: 2015-08-24 Last update: 2026-05-06 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2015-6525 is rated High Risk (65.5/100): CVSS High severity, with high exploitation likelihood (EPSS 4.81%, 91th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. EPSS rose +3.74% 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-2015-6525

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 1.07% 4.81% +3.74%
2 2025-08-20 0.50% 1.07% +0.57%
3 2025-06-14 — 0.50% —

Full EPSS history (8 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2015-6525

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 2.0 HIGH
AV:N/AC:L/Au:N/C:P/I:P/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:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 6.4 [email protected]

Weakness enumeration for CVE-2015-6525

OS Trackers for CVE-2015-6525

vendor priority summary link
debian not yet assigned CVE-2015-6525 not yet assigned priority: Debian including 1 source packages (libevent), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2015-6525
redhat medium — https://access.redhat.com/security/cve/CVE-2015-6525
ubuntu medium CVE-2015-6525 medium priority: Ubuntu including 1 source packages (libevent), 4 status rows across 4 suites (precise, trusty, upstream, vivid): released 3, not-affected 1. https://ubuntu.com/security/CVE-2015-6525

Affected software / configurations for CVE-2015-6525

Vendor Product Version Raw CPE
debian debian_linux 7.1 cpe:2.3:o:debian:debian_linux:7.1:*:*:*:*:*:*:*
libevent_project libevent 2.0.1 cpe:2.3:a:libevent_project:libevent:2.0.1:*:*:*:*:*:*:*
libevent_project libevent 2.0.2 cpe:2.3:a:libevent_project:libevent:2.0.2:*:*:*:*:*:*:*
libevent_project libevent 2.0.3 cpe:2.3:a:libevent_project:libevent:2.0.3:*:*:*:*:*:*:*
libevent_project libevent 2.0.4 cpe:2.3:a:libevent_project:libevent:2.0.4:*:*:*:*:*:*:*
libevent_project libevent 2.0.5 cpe:2.3:a:libevent_project:libevent:2.0.5:*:*:*:*:*:*:*
libevent_project libevent 2.0.6 cpe:2.3:a:libevent_project:libevent:2.0.6:*:*:*:*:*:*:*
libevent_project libevent 2.0.7 cpe:2.3:a:libevent_project:libevent:2.0.7:*:*:*:*:*:*:*
libevent_project libevent 2.0.8 cpe:2.3:a:libevent_project:libevent:2.0.8:*:*:*:*:*:*:*
libevent_project libevent 2.0.9 cpe:2.3:a:libevent_project:libevent:2.0.9:*:*:*:*:*:*:*
libevent_project libevent 2.0.10 cpe:2.3:a:libevent_project:libevent:2.0.10:*:*:*:*:*:*:*
libevent_project libevent 2.0.11 cpe:2.3:a:libevent_project:libevent:2.0.11:*:*:*:*:*:*:*
libevent_project libevent 2.0.12 cpe:2.3:a:libevent_project:libevent:2.0.12:*:*:*:*:*:*:*
libevent_project libevent 2.0.13 cpe:2.3:a:libevent_project:libevent:2.0.13:*:*:*:*:*:*:*
libevent_project libevent 2.0.14 cpe:2.3:a:libevent_project:libevent:2.0.14:*:*:*:*:*:*:*
libevent_project libevent 2.0.15 cpe:2.3:a:libevent_project:libevent:2.0.15:*:*:*:*:*:*:*
libevent_project libevent 2.0.16 cpe:2.3:a:libevent_project:libevent:2.0.16:*:*:*:*:*:*:*
libevent_project libevent 2.0.17 cpe:2.3:a:libevent_project:libevent:2.0.17:*:*:*:*:*:*:*
libevent_project libevent 2.0.18 cpe:2.3:a:libevent_project:libevent:2.0.18:*:*:*:*:*:*:*
libevent_project libevent 2.0.19 cpe:2.3:a:libevent_project:libevent:2.0.19:*:*:*:*:*:*:*
libevent_project libevent 2.0.20 cpe:2.3:a:libevent_project:libevent:2.0.20:*:*:*:*:*:*:*
libevent_project libevent 2.0.21 cpe:2.3:a:libevent_project:libevent:2.0.21:*:*:*:*:*:*:*
libevent_project libevent 2.1.1 cpe:2.3:a:libevent_project:libevent:2.1.1:*:*:*:*:*:*:*
libevent_project libevent 2.1.2 cpe:2.3:a:libevent_project:libevent:2.1.2:*:*:*:*:*:*:*
libevent_project libevent 2.1.3 cpe:2.3:a:libevent_project:libevent:2.1.3:*:*:*:*:*:*:*
libevent_project libevent 2.1.4 cpe:2.3:a:libevent_project:libevent:2.1.4:*:*:*:*:*:*:*

References for CVE-2015-6525

cvelogic Threat Intelligence