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CVE-2015-2091

16
FAUCET Score

CVE-2015-2091 describes a critical authentication bypass vulnerability in mod-gnutls versions 0.5.10 and earlier, affecting Apache web servers configured with this module. Despite GnuTLSClientVerify being set to "require," the authentication hook fails to properly validate client certificates, allowing remote attackers to spoof legitimate clients using crafted certificates. This vulnerability has a CVSS score of 5.0, indicating a medium severity, with low attack complexity and potential for unauthorized access (integrity impact). While no active exploitation, exploit code, or significant community discussion has been observed, the flaw could lead to unauthorized access to resources protected by client certificate authentication.

Impacted Technologies

VendorProductVersion(s)CPE
<= 0.5.1CPE matchmatch criteria
cpe:2.3:a:apache:mod-gnutls:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 2.0

5.0MEDIUM

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

Confidentiality Impact
NONE
Integrity Impact
PARTIAL
Availability Impact
NONE
Access Vector
NETWORK
Access Complexity
LOW
Authentication
NONE
Exploitability Score
10.0
Impact Score
2.9
CvssVersion
2.0

Exploit Intelligence

EPSS Score
3.25%
Probability of exploitation in next 30 days
EPSS Percentile
87.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-24
Model: v2026.06.15
This CVE's current EPSS score of 0.0325 is in the 82nd percentile among its peer group of 23,690 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, 0.0 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

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

Remediation

Remediation records are not available for this CVE.

References

issues.outoforder.cc / view.php
Vendor Advisory
bugs.debian.org / cgi-bin/bugreport.cgi
security.gentoo.org / glsa/201709-04
debian.org / security/2015/dsa-3177