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CVE-2026-104721— Logback: Incomplete protection against CVE-2026-19880

Quick assessment

Affected
QOS.CH Sarl Logback-classic
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.

QOS.CH Sarl Logback-classic for Java（logback-classic 模块）中存在路径遍历漏洞。具体而言，基于 MDC（Mapped Diagnostic Context）的判别器值未经过消毒处理，直接嵌套到 FileAppender 的路径中。攻击者若能影响该 MDC 值（例如通过 HTTP 请求头），即可在预期目录之外创建和追加日志文件。 该漏洞影响 Logback-classic 从 0.9.14 到 1.6.4 的所有版本。此漏洞与 CVE-2026-19880 类似，但

CVSS 6.3 · Medium EPSS 0.33% · P24

Affected Version Matrix 2

VendorProduct Version RangeStatus
QOS.CH Sarl Logback-classic 0.9.14≤ 1.6.4 affected
1.6.5 unaffected
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I. Basic Information for CVE-2026-104721

Vulnerability Information
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Vulnerability Title
Logback: Incomplete protection against CVE-2026-19880
Source: CVE Program / CVE List V5
Vulnerability Description
Path-traversal vulnerability in QOS.CH Sarl Logback-classic on Java (logback-classic module) allows path-traversal vulnerability. More specifically, an MDC-based discriminator value flows unsanitized into a nested FileAppender path, letting an attacker who influences that MDC value (e.g. via an HTTP header) create and append log files outside the intended directory. This issue affects Logback-classic: from 0.9.14 through 1.6.4.  This vulnerability is similar to CVE-2026-19880 but involves other attack techniques.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/S:P/AU:N/RE:M/U:Green
Source: CVE Program / CVE List V5
Vulnerability Type
对路径名的限制不恰当(路径遍历)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
QOS.CH Sarl Logback-classic 0.9.14 ~ 1.6.4 -

II. Public POCs for CVE-2026-104721

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III. Intelligence Information for CVE-2026-104721

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Vendor Pages for CVE-2026-104721 (1)

IV. Related Vulnerabilities

Same product: Logback-classic
Same vendor: QOS.CH Sarl
Same weakness: CWE-22

V. Comments for CVE-2026-104721

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