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CVE-2016-6263

26
FAUCET Score

CVE-2016-6263 describes an out-of-bounds read vulnerability in the stringprep_utf8_nfkc_normalize function within libidn versions prior to 1.33. This flaw allows remote attackers to trigger a denial of service (crash) by providing specially crafted UTF-8 data. With a CVSS score of 7.5 (High), it presents a significant risk due to its network-based attack vector and low attack complexity, potentially leading to system unavailability. Despite its severity, there is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
<= 1.32CPE matchmatch criteria
cpe:2.3:a:gnu:libidn:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

7.5HIGH

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.0

Exploit Intelligence

EPSS Score
3.91%
Probability of exploitation in next 30 days
EPSS Percentile
89.2%
Percentile rank of EPSS score among Peer Group
As of 2026-07-24
Model: v2026.06.15
This CVE's current EPSS score of 0.0391 is in the 81st percentile among its peer group of 51,466 CVEs.

Social Chatter

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 (3)

redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 5Fixed in: libidn
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: libidn
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: libidn

Vendor Advisories (1)

redhatCVE-2016-6263Low

libidn: Crash when given invalid UTF-8 data on input

Jan 14, 2016

References

git.savannah.gnu.org / cgit/libidn.git/commit
Issue TrackingPatch
lists.opensuse.org / opensuse-updates/2016-08/msg00005.html
Third Party Advisory
lists.opensuse.org / opensuse-updates/2016-08/msg00098.html
Third Party Advisory
lists.apache.org / thread.html/r58af02e294bd07f487e2c64ffc0a29b837db5600e33b6e698b9d696b%40%3Cissues.bookkeeper.apache.org%3E
lists.apache.org / thread.html/rf4c02775860db415b4955778a131c2795223f61cb8c6a450893651e4%40%3Cissues.bookkeeper.apache.org%3E
lists.gnu.org / archive/html/help-libidn/2016-07/msg00009.html
Vendor Advisory
security.gentoo.org / glsa/201908-06
debian.org / security/2016/dsa-3658
openwall.com / lists/oss-security/2016/07/20/6
Mailing ListThird Party Advisory
openwall.com / lists/oss-security/2016/07/21/4
Mailing ListThird Party Advisory
securityfocus.com / bid/92070
Third Party AdvisoryVDB Entry
ubuntu.com / usn/USN-3068-1
Third Party Advisory