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TI-2026-36123 Aliases CVE-2026-48859

SSH server timing side-channel in ssh_auth:check_password/3 allows unauthenticated username enumeration

Priority LOW 34CWE-208Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
Present
Impact type
Information disclosure
Confidentiality · integrity · availability
Low · None · None
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-208.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00354 29th percentileScored 2026-11-07
Fix Fixed OTP (Erlang): 29.0.2, 6.0.1

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
ErlangOTP29.0 to before 29.0.229.0.2Patch availableCNA
ErlangOTP6.0 to before 6.0.16.0.1Patch availableCNA
  • OTP VendorErlang Affected 29.0 to before 29.0.2 Fixed in 29.0.2 Patch available CNA
  • OTP VendorErlang Affected 6.0 to before 6.0.1 Fixed in 6.0.1 Patch available CNA

CPE configurations NVD · 2

CPEVersionsRoleVendor
cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:*29.0 to before 29.0.2VulnerableErlang
cpe:2.3:a:erlang:erlang\/ssh:*:*:*:*:*:*:*:*6.0 to before 6.0.1VulnerableErlang
  • cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:* Versions 29.0 to before 29.0.2 Vulnerable ·Erlang
  • cpe:2.3:a:erlang:erlang\/ssh:*:*:*:*:*:*:*:* Versions 6.0 to before 6.0.1 Vulnerable ·Erlang

Remediation

  • Fix · CNA OTP (Erlang) Fixed in 29.0.2
  • Fix · CNA OTP (Erlang) Fixed in 6.0.1

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-48859

References

Patch 1

Advisory 3

Other 1

  • TI-2025-23504 Erlang/OTP SSH Vulnerable to Pre-Authentication RCE KEVCVSS 3.1CRITICAL 10.0
  • TI-2023-26623 The SSH transport protocol with certain OpenSSH extensions, found in OpenSSH before 9.6… CVSS 3.1MEDIUM 5.9
  • TI-2017-14604 The Erlang otp TLS server answers with different TLS alerts to different error types in… CVSS 3.0MEDIUM 5.9
  • TI-2026-36669 Stack buffer overflow in SCTP error cause parsing in inet_drv allows remote VM crash CVSS 4.0HIGH 8.8
  • TI-2022-17230 In Erlang/OTP before 23.3.4.15, 24.x before 24.3.4.2, and 25.x before 25.0.2, there is a… CVSS 3.1CRITICAL 9.8
  • TI-2016-08327 An issue was discovered in Erlang/OTP 18.x. CVSS 3.0CRITICAL 9.8
See all 40 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences