CVE-2026-34743 | tukaani-project xz up to 5.8.2 Compression lzma_index_decoder heap-based overflow (GHSA-x872-m794-cxhv)

VDB-355024 · CVE-2026-34743 · GHSA-X872-M794-CXHV TUKAANI-PROJECT XZ UP TO 5.8.2 COMPRESSION LZMA_INDEX_DECODER HEAP-BASED OVERFLOW HISTORYDIFFRELATEJSONXMLCTI CVSS Meta Temp Score Current Exploit Price (≈) CTI Interest Score 5.1 $0-$5k 0.46 Summaryinfo A vulnerability described as critical has been identified in tukaani-project xz up to 5.8.2. Affected is the function lzma_index_decoder of the component Compression Handler. Executing a manipulation can lead to heap-based overflow. The identification of this vulnerability is CVE-2026-34743. The attack may be launched remotely. There is no exploit available. Upgrading the affected component is recommended. Detailsinfo A vulnerability classified as critical was found in tukaani-project xz up to 5.8.2. This vulnerability affects the function lzma_index_decoder of the component Compression Handler. The manipulation with an unknown input leads to a heap-based overflow vulnerability. The CWE definition for the vulnerability is CWE-122. A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc(). As an impact it is known to affect availability. CVE summarizes: 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. The advisory is shared for download at github.com. This vulnerability was named CVE-2026-34743 since 03/30/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are known technical details, but no exploit is available. Upgrading to version 5.8.3 eliminates this vulnerability. The upgrade is hosted for download at github.com. Applying the patch c8c22869e780ff57c96b46939c3d79ff99395f87 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version. Productinfo Type Project Management Software Vendor tukaani-project Name xz Version 5.8.0 5.8.1 5.8.2 License open-source Website Product: https://github.com/tukaani-project/xz/ CPE 2.3info 🔒 🔒 🔒 CPE 2.2info 🔒 🔒 🔒 CVSSv4info VulDB Vector: 🔒 VulDB Reliability: 🔍 CNA CVSS-B Score: 🔒 CNA CVSS-BT Score: 🔒 CNA Vector: 🔒 CVSSv3info VulDB Meta Base Score: 5.3 VulDB Meta Temp Score: 5.1 VulDB Base Score: 5.3 VulDB Temp Score: 5.1 VulDB Vector: 🔒 VulDB Reliability: 🔍 CVSSv2info Vector Complexity Authentication Confidentiality Integrity Availability Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock VulDB Base Score: 🔒 VulDB Temp Score: 🔒 VulDB Reliability: 🔍 Exploitinginfo Class: Heap-based overflow CWE: CWE-122 / CWE-119 CAPEC: 🔒 ATT&CK: 🔒 Physical: No Local: No Remote: Yes Availability: 🔒 Status: Not defined Price Prediction: 🔍 Current Price Estimation: 🔒 0-Day Unlock Unlock Unlock Unlock Today Unlock Unlock Unlock Unlock Threat Intelligenceinfo Interest: 🔍 Active Actors: 🔍 Active APT Groups: 🔍 Countermeasuresinfo Recommended: Upgrade Status: 🔍 0-Day Time: 🔒 Upgrade: xz 5.8.3 Patch: c8c22869e780ff57c96b46939c3d79ff99395f87 Timelineinfo 03/30/2026 CVE reserved 04/02/2026 +3 days Advisory disclosed 04/02/2026 +0 days VulDB entry created 04/03/2026 +0 days VulDB entry last update Sourcesinfo Product: github.com Advisory: GHSA-x872-m794-cxhv Status: Confirmed CVE: CVE-2026-34743 (🔒) GCVE (CVE): GCVE-0-2026-34743 GCVE (VulDB): GCVE-100-355024 Entryinfo Created: 04/03/2026 00:03 Changes: 04/03/2026 00:03 (74) Complete: 🔍 Cache ID: 99:9F4:101 Discussion No comments yet. Languages: en. Please log in to comment. ◂ PreviousOverviewNext ▸