Vulnerability Description
Observable Timing Discrepancy vulnerability in Erlang/OTP ssh (ssh_auth, ssh_options modules) allows unauthenticated remote username enumeration via timing side-channel in password authentication. When the SSH daemon is configured with the user_passwords or password option, ssh_auth:check_password/3 performs a PBKDF2-SHA256 computation with 600,000 iterations (~300ms) for valid usernames, but returns immediately (~0ms) for invalid usernames via the ssh_options:get_password_option/2 path. This timing difference is detectable in a single authentication attempt and allows an unauthenticated attacker to distinguish valid from invalid usernames. The user_passwords and password options are documented as intended for test purposes; the recommended alternative is pwdfun, which is not affected by this vulnerability. This vulnerability is associated with program files lib/ssh/src/ssh_auth.erl and lib/ssh/src/ssh_options.erl. This issue affects OTP from OTP 29.0 before OTP 29.0.2, corresponding to ssh from 6.0 before 6.0.1.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Erlang | Erlang\/Otp | >= 29.0, < 29.0.2 |
| Erlang | Erlang\/Ssh | >= 6.0, < 6.0.1 |
Related Weaknesses (CWE)
References
- https://cna.erlef.org/cves/CVE-2026-48859.htmlMitigationThird Party Advisory
- https://github.com/erlang/otp/commit/c342092ef4b369bb409d5b71ac8fd83bab74aedfPatch
- https://github.com/erlang/otp/security/advisories/GHSA-3w6p-vwhf-wvp4MitigationVendor Advisory
- https://osv.dev/vulnerability/EEF-CVE-2026-48859MitigationThird Party Advisory
- https://www.erlang.org/doc/system/versions.html#order-of-versionsProduct
FAQ
What is CVE-2026-48859?
CVE-2026-48859 is a vulnerability with a CVSS score of 5.3 (MEDIUM). Observable Timing Discrepancy vulnerability in Erlang/OTP ssh (ssh_auth, ssh_options modules) allows unauthenticated remote username enumeration via timing side-channel in password authentication. Wh...
How severe is CVE-2026-48859?
CVE-2026-48859 has been rated MEDIUM with a CVSS base score of 5.3/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-48859?
Check the references section above for vendor advisories and patch information. Affected products include: Erlang Erlang\/Otp, Erlang Erlang\/Ssh.