ESB-2026.4629

=========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2026.4629 libarchive security update 6 May 2026 =========================================================================== AUSCERT Security Bulletin Summary --------------------------------- Product: libarchive Publisher: Debian Operating System: Debian GNU/Linux Resolution: Patch/Upgrade CVE Names: CVE-2026-4111 CVE-2026-4424 CVE-2026-4426 CVE-2026-5121 Original Bulletin: https://lists.debian.org/debian-lts-announce/2026/05/msg00007.html Comment: CVSS (Max): 9.8 CVE-2026-5121 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H) CVSS Source: Red Hat, [CISA-ADP] Calculator: https://www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H EPSS (Max): 0.4% (58th) CVE-2026-4424 2026-05-05 - --------------------------BEGIN INCLUDED TEXT-------------------- - ------------------------------------------------------------------------- Debian LTS Advisory DLA-4563-1 debian-lts@lists.debian.org https://www.debian.org/lts/security/ Arnaud Rebillout May 05, 2026 https://wiki.debian.org/LTS - ------------------------------------------------------------------------- Package : libarchive Version : 3.4.3-2+deb11u4 CVE ID : CVE-2026-4111 CVE-2026-4424 CVE-2026-4426 CVE-2026-5121 Debian Bug : 1130753 1131444 1131446 1133002 Multiple vulnerabilities have been discovered in libarchive, a multi-format archive and compression C library, which also provides the following command-line tools: bsdcat, bsdcpio, bsdtar and bsdunzip. CVE-2026-4111 A flaw was identified in the RAR5 archive decompression logic of the libarchive library, specifically within the archive_read_data() processing path. When a specially crafted RAR5 archive is processed, the decompression routine may enter a state where internal logic prevents forward progress. This condition results in an infinite loop that continuously consumes CPU resources. Because the archive passes checksum validation and appears structurally valid, affected applications cannot detect the issue before processing. This can allow attackers to cause persistent denial-of-service conditions in services that automatically process archives. CVE-2026-4424 A flaw was found in libarchive. This heap out-of-bounds read vulnerability exists in the RAR archive processing logic due to improper validation of the LZSS sliding window size after transitions between compression methods. A remote attacker can exploit this by providing a specially crafted RAR archive, leading to the disclosure of sensitive heap memory information without requiring authentication or user interaction. CVE-2026-4426 A flaw was found in libarchive. An Undefined Behavior vulnerability exists in the zisofs decompression logic, caused by improper validation of a field (`pz_log2_bs`) read from ISO9660 Rock Ridge extensions. A remote attacker can exploit this by supplying a specially crafted ISO file. This can lead to incorrect memory allocation and potential application crashes, resulting in a denial-of-service (DoS) condition. CVE-2026-5121 A flaw was found in libarchive. On 32-bit systems, an integer overflow vulnerability exists in the zisofs block pointer allocation logic. A remote attacker can exploit this by providing a specially crafted ISO9660 image, which can lead to a heap buffer overflow. This could potentially allow for arbitrary code execution on the affected system. For Debian 11 bullseye, these problems have been fixed in version 3.4.3-2+deb11u4. We recommend that you upgrade your libarchive packages. For the detailed security status of libarchive please refer to its security tracker page at: https://security-tracker.debian.org/tracker/libarchive Further information about Debian LTS security advisories, how to apply these updates to your system and frequently asked questions can be found at: https://wiki.debian.org/LTS - --------------------------END INCLUDED TEXT---------------------- You have received this e-mail bulletin as a result of your organisation's registration with AUSCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. 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