CVE-2026-5121

High

Published: 30 March 2026

Published

30 March 2026

Modified

11 May 2026

KEV Added

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Patch

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CVSS Score 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS Score 0.0008 24.5th percentile

Risk Priority 15 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2026-5121 is a high-severity Integer Overflow or Wraparound (CWE-190) vulnerability in Redhat Enterprise Linux. Its CVSS base score is 7.5 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 24.5th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified are NIST 800-53 RA-5 (Vulnerability Monitoring and Scanning) and SI-2 (Flaw Remediation).

Threat & Defense at a Glance

What attackers do: exploitation maps to Exploit Public-Facing Application (T1190). What defenders deploy: see the NIST 800-53 controls recommended below.

Threat & Defense Details

Mitigating Controls (NIST 800-53 r5)AI

SI-2 Flaw Remediation good match

prevent

Directly mandates timely remediation of known flaws like CVE-2026-5121 in libarchive through patching, as evidenced by Red Hat errata.

RA-5 Vulnerability Monitoring and Scanning good match

detect

Enables identification of systems vulnerable to CVE-2026-5121 via regular scanning for library vulnerabilities on 32-bit architectures.

SI-16 Memory Protection partial match

prevent

Implements memory protections such as ASLR and DEP to mitigate heap buffer overflow exploitation from the libarchive integer overflow.

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access

Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.

attack.mitre.org →

Why these techniques?

The vulnerability allows remote unauthenticated attackers to achieve arbitrary code execution by supplying a malicious ISO9660 image to libarchive-dependent applications, directly mapping to exploitation of public-facing applications.

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

NVD Description

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.

Deeper analysisAI

CVE-2026-5121, published on 2026-03-30, is an integer overflow vulnerability (CWE-190) in the libarchive library's zisofs block pointer allocation logic on 32-bit systems. The flaw occurs when processing a specially crafted ISO9660 image, triggering a heap buffer overflow. It carries a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N), indicating high confidentiality impact.

A remote attacker requires no privileges or user interaction to exploit this vulnerability by providing a malicious ISO9660 image to any application or system component that uses libarchive for archive handling. Successful exploitation could potentially enable arbitrary code execution on the targeted 32-bit system.

Red Hat has issued several errata addressing CVE-2026-5121, including RHSA-2026:10065, RHSA-2026:10097, RHSA-2026:11768, RHSA-2026:8510, and RHSA-2026:8517. Practitioners should review and apply these updates to vulnerable Red Hat products utilizing libarchive on 32-bit architectures.