Vulnerability · Published Oct 4, 2026 · Assigned by VulnCheck

CVE-2026-105221Gist RubyGem before 6.1.0 Disabled TLS Certificate Verification

High 7.4

In plain English

A high-severity improper certificate validation in gist from defunkt. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 13% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code.

Severity (CVSS 3.1)7.4High

Exploit odds (30 days)0.2%top 86.6% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack tooling1Public PoC

Official description

The gist RubyGem before 6.1.0 contains an improper certificate validation vulnerability that allows on-path attackers to intercept HTTPS traffic because http_connection in lib/gist.rb sets VERIFY_NONE. Attackers can present any certificate to read or modify GitHub API traffic, stealing OAuth tokens and login credentials to read and modify the victim's gists.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Ubuntu:22.04:LTS	gist	no fix listed	UBUNTU-CVE-2026-105221
Ubuntu:24.04:LTS	gist	no fix listed	UBUNTU-CVE-2026-105221
Ubuntu:26.04:LTS	gist	no fix listed	UBUNTU-CVE-2026-105221
Ubuntu:26.10	gist	no fix listed	UBUNTU-CVE-2026-105221

Affected products (as reported)

Vendor	Product	Versions
defunkt	gist	4.0.0 – before 6.1.0

Weakness: CWE-295 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

References

GitHub Issue #373 issue-tracking
https://github.com/defunkt/gist product
https://github.com/defunkt/gist/blob/v6.0.0/lib/gist.rb#L466-L468 technical-description
https://github.com/defunkt/gist/commit/07ccc1a6d46e9d36f0e85d0b1c5d795890ae6bcf patch
VulnCheck Advisory: Gist RubyGem before 6.1.0 Disabled TLS Certificate Verification third-party-advisory