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CVE-2026-57166— PJSIP: Pre-authentication overflow in the telnet CLI error

Quick assessment

Affected
pjsip pjproject
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.

PJSIP 是一个用 C 语言编写的免费且开源的多媒体通信库。在提交 4472a31 之前，PJLIB-UTIL 的 Telnet CLI 前端在渲染用户输入的命令回显时存在一个栈缓冲区溢出漏洞。若干命令行处理路径将受攻击者影响的数据写入固定大小的缓冲区，且缺乏足够的边界检查，因此较长的命令行可能导致这些缓冲区溢出。此问题仅影响启用了 Telnet CLI 前端的应用程序（例如通过 或 启用）。由于 Telnet CLI 是一个无需身份验证的交互式管理接口，任何能够访问该端口的客户端本就可以直接下发任意 CLI 命

CVSS 6.3 · Medium

Possible ATT&CK Techniques 1 AI

T1059 · Command and Scripting Interpreter

Affected Version Matrix 1

VendorProduct Version RangeStatus
pjsip pjproject < 4472a31d77a7506ff175dad5abef490f4e31bed1 affected
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I. Basic Information for CVE-2026-57166

Vulnerability Information
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Vulnerability Title
PJSIP: Pre-authentication overflow in the telnet CLI error
Source: CVE Program / CVE List V5
Vulnerability Description
PJSIP is a free and open source multimedia communication library written in C. Prior to commit 4472a31, a stack buffer overflow exists in the PJLIB-UTIL telnet CLI front-end when rendering feedback for an entered command line. Several command-line handling paths write an attacker-influenced amount of data into fixed-size buffers without sufficient bounds checking, so a long command line can overflow them. This affects only applications that enable the telnet CLI front-end (e.g. pj_cli_telnet_create() / --cli-telnet-port). The telnet CLI is an interactive administration interface with no authentication, so any client able to reach it can already issue arbitrary CLI commands. A malformed or overly long command line can overflow a fixed-size stack buffer while rendering command-line feedback, which may lead to application termination. Because reaching this code already requires access to the unauthenticated CLI, the impact beyond that existing access is limited. Applications that do not enable the telnet CLI front-end are not affected. This issue has been patched via commit 4472a31.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
栈缓冲区溢出
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
pjsip pjproject < 4472a31d77a7506ff175dad5abef490f4e31bed1 -

II. Public POCs for CVE-2026-57166

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III. Intelligence Information for CVE-2026-57166

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Patches & Fixes for CVE-2026-57166 (1)

Vendor Advisories for CVE-2026-57166 (1)

Same Patch Batch · pjsip · 2026-09-04 · 8 CVEs total

CVE-2026-57163 8.8 HIGH PJSIP: Stack overflow parsing a TLS peer certificate's SubjectAltName in GnuTLS backend
CVE-2026-57162 8.8 HIGH PJSIP: Stack overflow parsing SDP a=crypto attributes
CVE-2026-57161 8.8 HIGH PJSIP: Stack overflow handling Service-Route headers in a registration response
CVE-2026-57159 8.4 HIGH PJSIP: SDP parser out-of-bounds write in remote payload-type map maintenance
CVE-2026-57164 8.3 HIGH PJSIP: Heap overflow in the HTTP client
CVE-2026-57160 6.9 MEDIUM PJSIP: SIP message header buffer overflow
CVE-2026-57165 6.3 MEDIUM PJSIP: Pre-authentication overflow in the telnet CLI history

IV. Related Vulnerabilities

Same product: pjproject
Same vendor: pjsip
Same weakness: CWE-121

V. Comments for CVE-2026-57166

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