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CVE-2026-48859— SSH server timing side-channel in ssh_auth:check_password/3 allows unauthenticated username enumeration

Quick assessment

Affected
Erlang OTP
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Erlang/OTP是Erlang/OTP开源的一个JavaScript编写的处理处理异常的库。该库可以捕捉node.js内置API引发的异常。 Erlang/OTP ssh 6.0至6.0.1之前版本存在安全漏洞，该漏洞源于ssh_auth模块在密码认证中对有效用户名执行PBKDF2-SHA256计算，对无效用户名立即返回，存在可观察的时间差异，可能导致未经身份验证的远程攻击者通过定时侧信道枚举有效用户名。

CVSS 6.3 · Medium EPSS 0.62% · P48

Possible ATT&CK Techniques 1 AI

T1083 · File and Directory Discovery

Affected Version Matrix 3

VendorProduct Version RangeStatus
Erlang OTP 29.0< 29.0.2 affected
6.0< 6.0.1 affected
032d1bc9491a3975c68faf9bc7776115d6ae3005< c342092ef4b369bb409d5b71ac8fd83bab74aedf affected
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I. Basic Information for CVE-2026-48859

Vulnerability Information
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Vulnerability Title
SSH server timing side-channel in ssh_auth:check_password/3 allows unauthenticated username enumeration
Source: CVE Program / CVE List V5
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
通过时间差异性导致的信息暴露
Source: CVE Program / CVE List V5
Vulnerability Title
Erlang/OTP 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Erlang/OTP是Erlang/OTP开源的一个JavaScript编写的处理处理异常的库。该库可以捕捉node.js内置API引发的异常。 Erlang/OTP ssh 6.0至6.0.1之前版本存在安全漏洞，该漏洞源于ssh_auth模块在密码认证中对有效用户名执行PBKDF2-SHA256计算，对无效用户名立即返回，存在可观察的时间差异，可能导致未经身份验证的远程攻击者通过定时侧信道枚举有效用户名。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Erlang OTP 29.0 ~ 29.0.2 cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:*
Erlang OTP 6.0 ~ 6.0.1 cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:*
Erlang OTP 032d1bc9491a3975c68faf9bc7776115d6ae3005 ~ c342092ef4b369bb409d5b71ac8fd83bab74aedf cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:*

II. Public POCs for CVE-2026-48859

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III. Intelligence Information for CVE-2026-48859

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Patches & Fixes for CVE-2026-48859 (1)

Vendor Advisories for CVE-2026-48859 (3)

Same Patch Batch · Erlang · 2026-06-10 · 7 CVEs total

CVE-2026-49759 8.8 HIGH Stack buffer overflow in SCTP error cause parsing in inet_drv allows remote VM crash
CVE-2026-48860 7.5 HIGH Distribution-over-TLS LAN allowlist silently bypassed due to sockname/peername confusion i
CVE-2026-48856 7.1 HIGH httpc leaks Authorization header to cross-origin redirect targets
CVE-2026-49760 6.9 MEDIUM Stack Buffer Overflow in ei_s_print_term at Very Large Integer
CVE-2026-48858 6.3 MEDIUM ftp client PASV response IP not validated against control peer, enabling SSRF and FTP boun
CVE-2026-48855 2.3 LOW SFTP READLINK Leaks Absolute Backend Filesystem Path When Root Is Configured

IV. Related Vulnerabilities

Same product: OTP
Same vendor: Erlang
Same weakness: CWE-208

V. Comments for CVE-2026-48859

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