CVE-2018-16840

Name: CVE-2018-16840
Creator: NVD / NIST
Published: 2018-10-31T18:29:00.307+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 3.33%

Last modified Jun 17, 2026

CVE-2018-16840 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. A heap use-after-free flaw was found in curl versions from 7.59.0 through 7.61.1 in the code related to closing an easy handle. When closing and cleaning up an 'easy' handle in the `Curl_close()` function, the library code first frees a struct (without nulling the pointer) and might then subsequently erroneously write to a struct field within that already freed struct.. EPSS estimates a 3.33% chance of exploitation in the next 30 days.

Description

A heap use-after-free flaw was found in curl versions from 7.59.0 through 7.61.1 in the code related to closing an easy handle. When closing and cleaning up an 'easy' handle in the `Curl_close()` function, the library code first frees a struct (without nulling the pointer) and might then subsequently erroneously write to a struct field within that already freed struct.

Metrics

CVSS 3.1

9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

3.33%

87.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Haxx	Curl	>= 7.59.0, < 7.62.0
Canonical	Ubuntu Linux	14.04
Canonical	Ubuntu Linux	16.04
Canonical	Ubuntu Linux	18.04
Canonical	Ubuntu Linux	18.10

References

http://www.securitytracker.com/id/1042013Third Party Advisory, VDB Entry
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2018-16840Issue Tracking, Third Party Advisory
https://curl.haxx.se/docs/CVE-2018-16840.htmlPatch, Vendor Advisory
https://github.com/curl/curl/commit/81d135d67155c5295b1033679c606165d4e28f3fPatch, Third Party Advisory
https://security.gentoo.org/glsa/201903-03Third Party Advisory
https://usn.ubuntu.com/3805-1/Third Party Advisory
http://www.securitytracker.com/id/1042013Third Party Advisory, VDB Entry
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2018-16840Issue Tracking, Third Party Advisory
https://curl.haxx.se/docs/CVE-2018-16840.htmlPatch, Vendor Advisory
https://github.com/curl/curl/commit/81d135d67155c5295b1033679c606165d4e28f3fPatch, Third Party Advisory
https://security.gentoo.org/glsa/201903-03Third Party Advisory
https://usn.ubuntu.com/3805-1/Third Party Advisory

Timeline

Published: Oct 31, 2018
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2018-16840?

How severe is CVE-2018-16840?

CVE-2018-16840 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 3.33% probability of exploitation in the next 30 days.

How do I fix CVE-2018-16840?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2018-16840?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST