CVE-2026-20889

CriticalPublic PoC

Published: 07 April 2026

Published

07 April 2026

Modified

10 April 2026

KEV Added

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Patch

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CVSS Score 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Score 0.0006 18.0th percentile

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

Summary

CVE-2026-20889 is a critical-severity Integer Overflow or Wraparound (CWE-190) vulnerability in Libraw Libraw. Its CVSS base score is 9.8 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 18.0th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified are NIST 800-53 SI-10 (Information Input Validation) and SI-2 (Flaw Remediation).

Threat & Defense at a Glance

What attackers do: exploitation maps to Exploit Public-Facing Application (T1190) and 2 other techniques. 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

Remediating the known heap buffer overflow in LibRaw's x3f_thumb_loader via patching directly eliminates the vulnerability exploitable by malicious files.

SI-10 Information Input Validation good match

prevent

Validating specially crafted image files prior to processing by LibRaw's x3f_thumb_loader prevents heap buffer overflows from malformed inputs.

SI-16 Memory Protection partial match

prevent

Implementing memory protections like ASLR and DEP mitigates exploitation of the heap buffer overflow in LibRaw by hindering arbitrary code execution.

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 →

T1203 Exploitation for Client Execution Execution

Adversaries may exploit software vulnerabilities in client applications to execute code.

attack.mitre.org →

T1204.002 Malicious File Execution

An adversary may rely upon a user opening a malicious file in order to gain execution.

attack.mitre.org →

Why these techniques?

Heap buffer overflow in LibRaw file parser enables remote exploitation of public-facing apps via malicious image file for RCE (T1190/T1203/T1204.002).

Confidence: HIGH · MITRE ATT&CK Enterprise v18.1

NVD Description

A heap-based buffer overflow vulnerability exists in the x3f_thumb_loader functionality of LibRaw Commit d20315b. A specially crafted malicious file can lead to a heap buffer overflow. An attacker can provide a malicious file to trigger this vulnerability.

Deeper analysisAI

CVE-2026-20889 is a heap-based buffer overflow vulnerability in the x3f_thumb_loader functionality of LibRaw at commit d20315b, published on 2026-04-07T15:17:35.300. The flaw, classified under CWE-190, can be triggered by processing a specially crafted malicious file, leading to a heap buffer overflow. It has a CVSS v3.1 base score of 9.8 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H), indicating critical severity.

A remote attacker requires no privileges or user interaction to exploit this vulnerability by providing a malicious file to a LibRaw-based application. Successful exploitation can result in high impacts to confidentiality, integrity, and availability, potentially allowing arbitrary code execution or denial of service on the affected system.

The primary advisories are documented in the Talos Intelligence reports at https://talosintelligence.com/vulnerability_reports/TALOS-2026-2358 and https://www.talosintelligence.com/vulnerability_reports/TALOS-2026-2358.