{"id":"CVE-2026-107147","kind":"vulnerability","aliases":["CVE-2026-107147"],"related":[],"title":"Roundcube 2FA plugin: spoofed client headers let attackers skip second factor","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.\n\n\n\n\nThis issue was fixed in commit 4640889.","summary":"The twofactor_gauthenticator plugin for Roundcube trusts the Client-IP and X-Forwarded-For headers without validation. An attacker who already has a user's password can spoof a whitelisted IP address and skip the second factor login step.","severity":"medium","cvss":6.3,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["email","package","php","roundcube","self-hosted"],"not_affected_if":["no-ip-whitelist","plugin-not-installed"],"how_to_check":"- Check whether the `twofactor_gauthenticator` plugin is installed in the Roundcube `plugins/` directory, and which commit or version it is at.\n- Check whether the plugin's IP whitelist is configured in its settings; the sources do not name the exact setting, so unknown.","fix":"- Update `twofactor_gauthenticator` to a build that includes commit `4640889`; the release version is unknown from the sources.\n- Until updated, unknown; the sources name no workaround.","status":"open","published_at":"2026-10-27T10:16:54+00:00","first_seen_at":"2026-10-27T10:31:02+00:00","triaged_at":"2026-10-27T10:31:59+00:00","updated_at":"2026-10-27T10:31:59+00:00","category":"package","confidence":0.7,"triage":{"at":"2026-10-27T10:31:59Z","model":"claude-haiku-5-5","output":{"fix":"- Update `twofactor_gauthenticator` to a build that includes commit `4640889`; the release version is unknown from the sources.\n- Until updated, unknown; the sources name no workaround.","reach":"internet","title":"Roundcube 2FA plugin: spoofed client headers let attackers skip second factor","impact":"high","summary":"The twofactor_gauthenticator plugin for Roundcube trusts the Client-IP and X-Forwarded-For headers without validation. An attacker who already has a user's password can spoof a whitelisted IP address and skip the second factor login step.","category":"package","nicknames":[],"who_cares":["roundcube","self-hosted","email","php"],"confidence":0.7,"needs_auth":"yes","worst_case":"Attacker logs into mail account with password alone, bypassing 2FA","analyst_note":"Check the NVD entry and fix commit 4640889 for the affected and fixed plugin versions and whether the whitelist is required.","how_to_check":"- Check whether the `twofactor_gauthenticator` plugin is installed in the Roundcube `plugins/` directory, and which commit or version it is at.\n- Check whether the plugin's IP whitelist is configured in its settings; the sources do not name the exact setting, so unknown.","needs_analyst":true,"not_affected_if":["plugin-not-installed","no-ip-whitelist"],"who_is_affected":"Deployments of Roundcube that run the twofactor_gauthenticator plugin and use an IP whitelist for second-factor exemption are exposed, since the bypass depends on the whitelist trusting spoofed headers. Sites without this plugin, or without a whitelisted-IP exemption, are not affected by this description.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"unknown"},"cost_usd":0.000649,"input_tokens":3357,"output_tokens":627,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-107147':14A,17A '-2026':13A,16A '2fa':2A,75C '4640889':126C 'address':58B,81C,112C 'alreadi':47B 'attack':8A,45B,101C 'authent':76C 'bypass':77C,119C 'client':5A,34B,80C,92C 'client-ip':33B,91C 'commit':125C 'cve':12A,15A 'due':83C 'email':18B 'factor':11A,63B,117C 'fix':123C 'forward':39B,97C 'gauthent':27B,68C 'header':6A,41B,82C,99C 'host':24B 'ip':35B,57B,93C,111C 'issu':121C 'lack':86C 'let':7A 'login':64B 'obtain':103C 'packag':19B 'password':52B,106C 'php':20B 'plugin':3A,28B,69C 'result':113C 'roundcub':1A,21B,30B,71C 'second':10A,62B,116C 'self':23B 'self-host':22B 'skip':9A,60B 'spoof':4A,54B,79C,108C 'step':65B 'trust':31B 'twofactor':26B,67C 'user':50B,104C 'valid':43B,88C 'vulner':73C 'whitelist':56B,110C 'without':42B 'x':38B,96C 'x-forwarded-for':37B,95C","nicknames":[],"mitigations":[],"who_affected":"Deployments of Roundcube that run the twofactor_gauthenticator plugin and use an IP whitelist for second-factor exemption are exposed, since the bypass depends on the whitelist trusting spoofed headers. Sites without this plugin, or without a whitelisted-IP exemption, are not affected by this description.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-27T10:16:54+00:00","kev":null,"cvss_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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","cvss_by":"cvd@cert.pl","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-107147","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-107147","severity":null,"published_at":"2026-10-27T10:16:54+00:00","modified_at":"2026-10-27T10:16:54+00:00","first_seen_at":"2026-10-27T10:31:02+00:00","fetched_at":"2026-10-27T10:31:02+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}