Vulnerability · Published Oct 27, 2026 · Assigned by CERT-PL

CVE-2026-107147Authentication bypass by spoofing in twofactor_gauthenticator

Medium 6.3

In plain English

A medium-severity authentication bypass by spoofing in twofactor_gauthenticator from alexandregz. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 34% of all known vulnerabilities).

Severity (CVSS 4.0)6.3Medium

Exploit odds (30 days)0.4%top 66.4% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

The twofactor_gauthenticator plugin for Roundcube is vulnerable to 2fa authentication bypass by spoofed client address headers. Due to the lack of validation of the Client-IP and X-Forwarded-For headers, an attacker who obtains user's password can spoof a whitelisted IP address, resulting in the second factor being bypassed. This issue was fixed in commit 4640889.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Ubuntu:26.10	roundcube	no fix listed	UBUNTU-CVE-2026-107147

Affected products (as reported)

Vendor	Product	Versions
alexandregz	twofactor_gauthenticator	0 – before 4640889

Weakness: CWE-290 · Vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

References

https://cert.pl/en/posts/2026/10/CVE-2026-107145 third-party-advisory
https://github.com/alexandregz/twofactor_gauthenticator/blob/master/CHANGES-2FA-SECURITY.en.md patch