CVE-2018-8778

Name: CVE-2018-8778
Creator: NVD / NIST
Published: 2018-04-03T22:29:00.773+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

UnknownEPSS 7.83%

Last modified Jun 17, 2026

CVE-2018-8778 is a vulnerability of currently unknown severity. In Ruby before 2.2.10, 2.3.x before 2.3.7, 2.4.x before 2.4.4, 2.5.x before 2.5.1, and 2.6.0-preview1, an attacker controlling the unpacking format (similar to format string vulnerabilities) can trigger a buffer under-read in the String#unpack method, resulting in a massive and controlled information disclosure.. EPSS estimates a 7.83% chance of exploitation in the next 30 days.

Description

In Ruby before 2.2.10, 2.3.x before 2.3.7, 2.4.x before 2.4.4, 2.5.x before 2.5.1, and 2.6.0-preview1, an attacker controlling the unpacking format (similar to format string vulnerabilities) can trigger a buffer under-read in the String#unpack method, resulting in a massive and controlled information disclosure.

Metrics

EPSS Probability

7.83%

93.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-134

Affected Software

Vendor	Product	Versions	Update
Ruby-Lang	Ruby	>= 2.2.0, < 2.2.10	—
Ruby-Lang	Ruby	>= 2.3.0, < 2.3.7	—
Ruby-Lang	Ruby	>= 2.4.0, < 2.4.4	—
Ruby-Lang	Ruby	>= 2.5.0, < 2.5.1	—
Ruby-Lang	Ruby	2.6.0	Preview1
Canonical	Ubuntu Linux	14.04	—
Canonical	Ubuntu Linux	16.04	—
Canonical	Ubuntu Linux	17.10	—
Debian	Debian Linux	7.0	—
Debian	Debian Linux	8.0	—
Debian	Debian Linux	9.0	—
Redhat	Enterprise Linux	6.0	—
Redhat	Enterprise Linux	7.0	—
Redhat	Enterprise Linux	7.4	—
Redhat	Enterprise Linux	7.5	—
Redhat	Enterprise Linux	7.6	—

References

http://lists.opensuse.org/opensuse-security-announce/2019-07/msg00036.html
http://www.securityfocus.com/bid/103693Third Party Advisory, VDB Entry
http://www.securitytracker.com/id/1042004Third Party Advisory, VDB Entry
https://access.redhat.com/errata/RHSA-2018:3729Third Party Advisory
https://access.redhat.com/errata/RHSA-2018:3730Third Party Advisory
https://access.redhat.com/errata/RHSA-2018:3731Third Party Advisory
https://access.redhat.com/errata/RHSA-2019:2028
https://lists.debian.org/debian-lts-announce/2018/04/msg00023.htmlMailing List, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2018/04/msg00024.htmlMailing List, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2018/07/msg00012.htmlMailing List, Third Party Advisory
https://usn.ubuntu.com/3626-1/Third Party Advisory
https://www.debian.org/security/2018/dsa-4259Third Party Advisory
https://www.ruby-lang.org/en/news/2018/03/28/buffer-under-read-unpack-cve-2018-8778/Vendor Advisory
https://www.ruby-lang.org/en/news/2018/03/28/ruby-2-2-10-released/Patch, Vendor Advisory
https://www.ruby-lang.org/en/news/2018/03/28/ruby-2-3-7-released/Patch, Vendor Advisory
https://www.ruby-lang.org/en/news/2018/03/28/ruby-2-4-4-released/Patch, Vendor Advisory
https://www.ruby-lang.org/en/news/2018/03/28/ruby-2-5-1-released/Patch, Vendor Advisory
http://lists.opensuse.org/opensuse-security-announce/2019-07/msg00036.html
http://www.securityfocus.com/bid/103693Third Party Advisory, VDB Entry
http://www.securitytracker.com/id/1042004Third Party Advisory, VDB Entry
https://access.redhat.com/errata/RHSA-2018:3729Third Party Advisory
https://access.redhat.com/errata/RHSA-2018:3730Third Party Advisory
https://access.redhat.com/errata/RHSA-2018:3731Third Party Advisory
https://access.redhat.com/errata/RHSA-2019:2028
https://lists.debian.org/debian-lts-announce/2018/04/msg00023.htmlMailing List, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2018/04/msg00024.htmlMailing List, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2018/07/msg00012.htmlMailing List, Third Party Advisory
https://usn.ubuntu.com/3626-1/Third Party Advisory
https://www.debian.org/security/2018/dsa-4259Third Party Advisory
https://www.ruby-lang.org/en/news/2018/03/28/buffer-under-read-unpack-cve-2018-8778/Vendor Advisory
https://www.ruby-lang.org/en/news/2018/03/28/ruby-2-2-10-released/Patch, Vendor Advisory
https://www.ruby-lang.org/en/news/2018/03/28/ruby-2-3-7-released/Patch, Vendor Advisory
https://www.ruby-lang.org/en/news/2018/03/28/ruby-2-4-4-released/Patch, Vendor Advisory
https://www.ruby-lang.org/en/news/2018/03/28/ruby-2-5-1-released/Patch, Vendor Advisory

Timeline

Published: Apr 3, 2018
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2018-8778?

How severe is CVE-2018-8778?

Severity scoring for CVE-2018-8778 is pending analysis. The EPSS model estimates a 7.83% probability of exploitation in the next 30 days.

How do I fix CVE-2018-8778?

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-2018-8778?

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

Scan your code now

Source: NVD / NIST