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CVE-2026-129483— Cyrus SASL through 2.1.28 SRP Authentication Bypass via plugins/srp.c

Quick assessment

Affected
cyrusimap cyrus-sasl
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.

Cyrus SASL 2.1.28 及更早版本在 SRP 服务器机制中存在身份验证绕过漏洞。由于 函数未拒绝客户端发送的、为 N 的倍数的公钥值 A，未经身份验证的网络攻击者可以发送等于 N 的 A 值，强制生成零共享密钥。这使得攻击者无需密码即可冒充任何现有用户进行身份验证，并获取会话密钥。

CVSS 9.1 · Critical

Affected Version Matrix 1

VendorProduct Version RangeStatus
cyrusimap cyrus-sasl ≤ 2.1.28 affected
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I. Basic Information for CVE-2026-129483

Vulnerability Information
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Vulnerability Title
Cyrus SASL through 2.1.28 SRP Authentication Bypass via plugins/srp.c
Source: CVE Program / CVE List V5
Vulnerability Description
Cyrus SASL through 2.1.28 contains an authentication bypass vulnerability in the SRP server mechanism because srp_server_mech_step2 does not reject client public values A that are multiples of N. Unauthenticated network clients can send A equal to N to force a zero shared secret, authenticating as any existing user without the password and learning session keys.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
认证机制不恰当
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
cyrusimap cyrus-sasl 0 ~ 2.1.28 -

II. Public POCs for CVE-2026-129483

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III. Intelligence Information for CVE-2026-129483

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Patches & Fixes for CVE-2026-129483 (1)

Vendor Advisories for CVE-2026-129483 (1)

Proof of Concept for CVE-2026-129483 (1)

Mailing List Discussions for CVE-2026-129483 (1)

Other References for CVE-2026-129483 (2)

IV. Related Vulnerabilities

Same vendor: cyrusimap
Same weakness: CWE-287