Assessment
Why it matters
CISA lists this vulnerability as known to be exploited; exploitation is confirmed; EPSS is 81.7%; technical severity is CVSS 9.8.
An issue was discovered in the base64d function in the SMTP listener in Exim before 4.90.1. By sending a handcrafted message, a buffer overflow may happen. This can be used to execute code remotely.
Who should care
- Teams operating Ubuntu Linux, Debian Linux, Exim
- Vulnerability and exposure management teams
- Security operations teams monitoring exploitation activity
Response plan
What I would do
- Confirm whether Ubuntu Linux, Debian Linux, Exim is present in the environment.
- Identify affected versions and establish whether vulnerable services are exposed or reachable.
- Apply updates per vendor instructions.
- Review relevant security telemetry for evidence of attempted or successful exploitation.
- Document the remediation decision and track it to verified completion.
Vendor remediation
Patch and remediation links
Use the vendor source below to confirm the correct fixed version, package or mitigation for your affected product.
Technical details
- CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CWE
- CWE-119
- Affected versions
- Canonical Ubuntu Linux (Version: 17.10); Debian Debian Linux (Version: 9.0); Exim Exim (End Excluding: 4.90.1)
- Published
- 8 February 2018
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
Signal timeline
- CVE published
- Added to CISA KEV
- Latest EPSS score: 81.7%
- Signal calculated at 86
External references
- Government advisory from www.cisa.gov
- Third-party advisory from openwall.com
- Exploit information from packetstormsecurity.com
- Third-party advisory from www.openwall.com
- Third-party advisory from www.securityfocus.com
- Third-party advisory from www.securitytracker.com
- Exploit information from devco.re
- Vendor advisory from exim.org
- Third-party advisory from lists.debian.org
- Third-party advisory from usn.ubuntu.com
- Third-party advisory from www.debian.org
- Exploit information from www.exploit-db.com