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CVE-2016-3739

23
FAUCET Score

CVE-2016-3739 describes a server spoofing vulnerability in cURL and libcurl versions prior to 7.49.0, specifically affecting the mbed_connect_step1 and polarssl_connect_step1 functions when using SSLv3 or TLS connections to numerical IP addresses. This medium-severity vulnerability (CVSS 5.3) has a network attack vector and high integrity impact, allowing remote attackers to spoof servers using any valid certificate, but requires user interaction and has high attack complexity. There is no evidence of active exploitation, public exploit code, or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
7.21.0CPE matchmatch criteria
cpe:2.3:a:haxx:curl:7.21.0:*:*:*:*:*:*:*
7.21.1CPE matchmatch criteria
cpe:2.3:a:haxx:curl:7.21.1:*:*:*:*:*:*:*
7.21.2CPE matchmatch criteria
cpe:2.3:a:haxx:curl:7.21.2:*:*:*:*:*:*:*
7.21.3CPE matchmatch criteria
cpe:2.3:a:haxx:curl:7.21.3:*:*:*:*:*:*:*
7.21.4CPE matchmatch criteria
cpe:2.3:a:haxx:curl:7.21.4:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

5.3MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
HIGH
Availability Impact
NONE
Exploitability Score
1.6
Impact Score
3.6
CvssVersion
3.0

Exploit Intelligence

EPSS Score
6.38%
Probability of exploitation in next 30 days
EPSS Percentile
92.9%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0638 is in the 93rd percentile among its peer group of 705 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.2 Bluesky, 0.0 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.2 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

jitsipatch availablevia llm_extracted
Fixed in: 7.48.0
View patch
sierra_wirelesspatch availablevia llm_extracted
Fixed in: 7.48.0
View patch

Vendor Advisories (3)

redhatCVE-2016-3739Moderate

curl: TLS certificate name check bypass with mbedTLS and PolarSSL

May 18, 2016
sierra_wirelessllm-sierra_wireless-887ea27965706b68HIGH

TLS certificate check bypass with mbedTLS/PolarSSL

May 18, 2016
jitsillm-jitsi-33a47d876dd8975bHIGH

TLS certificate check bypass with mbedTLS/PolarSSL

May 18, 2016

References

curl.haxx.se / changes.html
curl.haxx.se / CVE-2016-3739.patch
Vendor Advisory
curl.haxx.se / docs/adv_20160518.html
Vendor Advisory
h20566.www2.hpe.com / portal/site/hpsc/public/kb/docDisplay
h20566.www2.hpe.com / portal/site/hpsc/public/kb/docDisplay
security.gentoo.org / glsa/201701-47
openwall.com / lists/oss-security/2024/03/27/4
oracle.com / technetwork/security-advisory/cpuoct2018-4428296.html
securityfocus.com / bid/90726
securitytracker.com / id/1035907
slackware.com / security/viewer.php