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CVE-2018-16840

33
FAUCET Score

CVE-2018-16840 is a critical heap use-after-free vulnerability affecting curl versions 7.59.0 through 7.61.1, including canonical and haxx curl implementations. This flaw occurs when closing an easy handle, where the library frees a struct but then attempts to write to a field within that freed memory. With a CVSS score of 9.8 (CRITICAL), it presents a severe risk due to its network-based attack vector, low attack complexity, and potential for complete compromise of confidentiality, integrity, and availability. While there is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB) is currently unavailable; however, the vulnerability has garnered significant community discussion, indicating awareness among security researchers.

Impacted Technologies

VendorProductVersion(s)CPE
>= 7.59.0, < 7.62.0CPE matchmatch criteria
cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:*
14.04CPE matchmatch criteria
cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:lts:*:*:*
16.04CPE matchmatch criteria
cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*
18.04CPE matchmatch criteria
cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*
18.10CPE matchmatch criteria
cpe:2.3:o:canonical:ubuntu_linux:18.10:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

4.3MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
2.8
Impact Score
1.4
CvssVersion
3.0

Exploit Intelligence

EPSS Score
3.40%
Probability of exploitation in next 30 days
EPSS Percentile
87.6%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0340 is in the 80th percentile among its peer group of 36,897 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (6)

github_advisorypatch availablevia nvd_reference
View patch
jitsipatch availablevia llm_extracted
Fixed in: 7.61.1
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services Apache HTTP Server 2.4.29 SP2
View patch
sierra_wirelesspatch availablevia llm_extracted
Fixed in: 7.61.1
View patch
redhatvendor investigatingvia redhat_api
Product: Red Hat Software CollectionsFixed in: httpd24-curl
redhatno patchvia redhat_api
Product: Red Hat JBoss Core ServicesFixed in: jbcs-httpd24-curl

Vendor Advisories (3)

redhatCVE-2018-16840Low

curl: Use-after-free when closing "easy" handle in Curl_close()

Oct 31, 2018
sierra_wirelessllm-sierra_wireless-22e92e725bacc805LOW

use after free in handle close

Oct 31, 2018
jitsillm-jitsi-2e1f6efd223d4cdeLOW

use after free in handle close

Oct 31, 2018

References

bugzilla.redhat.com / show_bug.cgi
Issue TrackingThird Party Advisory
curl.haxx.se / docs/CVE-2018-16840.html
PatchVendor Advisory
github.com / curl/curl/commit/81d135d67155c5295b1033679c606165d4e28f3f
PatchThird Party Advisory
security.gentoo.org / glsa/201903-03
Third Party Advisory
usn.ubuntu.com / 3805-1
Third Party Advisory
securitytracker.com / id/1042013
Third Party AdvisoryVDB Entry