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CVE-2015-6525

21
FAUCET Score

CVE-2015-6525 describes multiple integer overflows in the Libevent evbuffer API (versions 2.0.x before 2.0.22 and 2.1.x before 2.1.5-beta), affecting Debian Linux and Libevent. These overflows, triggered by "insanely large inputs" to functions like evbuffer_add, can lead to denial of service via heap-based buffer overflows or infinite loops. With a CVSS score of 7.5, this vulnerability is considered high severity, allowing unauthenticated attackers over a network to achieve partial confidentiality, integrity, and availability impacts. There is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
7.1CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:7.1:*:*:*:*:*:*:*
2.0.1CPE matchmatch criteria
cpe:2.3:a:libevent_project:libevent:2.0.1:*:*:*:*:*:*:*
2.0.2CPE matchmatch criteria
cpe:2.3:a:libevent_project:libevent:2.0.2:*:*:*:*:*:*:*
2.0.3CPE matchmatch criteria
cpe:2.3:a:libevent_project:libevent:2.0.3:*:*:*:*:*:*:*
2.0.4CPE matchmatch criteria
cpe:2.3:a:libevent_project:libevent:2.0.4:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 2.0

7.5HIGH

AV:N/AC:L/Au:N/C:P/I:P/A:P

Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
Access Vector
NETWORK
Access Complexity
LOW
Authentication
NONE
Exploitability Score
10.0
Impact Score
6.4
CvssVersion
2.0

Exploit Intelligence

EPSS Score
4.81%
Probability of exploitation in next 30 days
EPSS Percentile
91.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-26
Model: v2026.06.15
This CVE's current EPSS score of 0.0481 is in the 84th percentile among its peer group of 51,485 CVEs.

Social Chatter

No social media mentions found for this CVE.

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Vendor Patches (8)

redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: thunderbird
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: firefox
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: libevent
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: thunderbird
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: firefox
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 5Fixed in: firefox
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 5Fixed in: thunderbird
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: chromium-browser

Vendor Advisories (1)

redhatCVE-2015-6525Moderate

libevent: multiple integer overflows in the evbuffer APIs

Aug 24, 2015

References

archives.seul.org / libevent/users/Jan-2015/msg00010.html
Vendor Advisory
debian.org / security/2015/dsa-3119