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CVE-2026-34743— XZ Utils: Buffer overflow in lzma_index_append()

Quick assessment

Affected
tukaani-project xz
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.

XZ Utils是Tukaani开源的一个实用程序。 XZ Utils 5.8.3之前版本存在安全漏洞，该漏洞源于lzma_index_decoder解码无记录的索引时状态异常，可能导致后续lzma_index_append分配内存不足并发生缓冲区溢出。

AI Predicted 7.5 Difficulty: Easy EPSS 0.57% · P45

Affected Version Matrix 1

VendorProduct Version RangeStatus
tukaani-project xz < 5.8.3 affected
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I. Basic Information for CVE-2026-34743

Vulnerability Information
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Vulnerability Title
XZ Utils: Buffer overflow in lzma_index_append()
Source: CVE Program / CVE List V5
Vulnerability Description
XZ Utils provide a general-purpose data-compression library plus command-line tools. Prior to version 5.8.3, if lzma_index_decoder() was used to decode an Index that contained no Records, the resulting lzma_index was left in a state where where a subsequent lzma_index_append() would allocate too little memory, and a buffer overflow would occur. This issue has been patched in version 5.8.3.
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/E:U
Source: CVE Program / CVE List V5
Vulnerability Type
堆缓冲区溢出
Source: CVE Program / CVE List V5
Vulnerability Title
XZ Utils 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
XZ Utils是Tukaani开源的一个实用程序。 XZ Utils 5.8.3之前版本存在安全漏洞，该漏洞源于lzma_index_decoder解码无记录的索引时状态异常，可能导致后续lzma_index_append分配内存不足并发生缓冲区溢出。
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
tukaani-project xz < 5.8.3 -

II. Public POCs for CVE-2026-34743

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III. Intelligence Information for CVE-2026-34743

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Patches & Fixes for CVE-2026-34743 (1)

Vendor Advisories for CVE-2026-34743 (1)

Vendor Pages for CVE-2026-34743 (1)

IV. Related Vulnerabilities

Same product: xz
Same vendor: tukaani-project
Same weakness: CWE-122

V. Comments for CVE-2026-34743

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