CVE-2026-31801

HighPublic PoC

Published: 10 March 2026

Published

10 March 2026

Modified

18 March 2026

KEV Added

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Patch

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CVSS Score 7.7 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:N

EPSS Score 0.0004 11.3th percentile

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

Summary

CVE-2026-31801 is a high-severity Incorrect Authorization (CWE-863) vulnerability in Zotregistry Zot. Its CVSS base score is 7.7 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 11.3th 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 AC-24 (Access Control Decisions) and AC-3 (Access Enforcement).

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

AC-3 Access Enforcement good match

prevent

AC-3 requires systems to enforce approved authorizations for access to resources like manifests, directly preventing the authorization bypass that allowed create-only users to overwrite the 'latest' tag.

AC-24 Access Control Decisions good match

prevent

AC-24 mandates accurate determination of required actions and authorization decisions for PUT requests, countering the flawed middleware logic that defaulted to 'create' instead of 'update'.

SI-2 Flaw Remediation good match

prevent

SI-2 ensures timely identification, reporting, and correction of flaws like this authorization bypass, as fixed in zot version 2.1.15.

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 →

T1195.002 Compromise Software Supply Chain Initial Access

Adversaries may manipulate application software prior to receipt by a final consumer for the purpose of data or system compromise.

attack.mitre.org →

T1608.001 Upload Malware Resource Development

Adversaries may upload malware to third-party or adversary controlled infrastructure to make it accessible during targeting.

attack.mitre.org →

Why these techniques?

Public-facing OCI registry auth bypass (PUT /v2/.../manifests) directly enables T1190 exploitation and facilitates T1195.002/T1608.001 by allowing overwrite of trusted images with malicious ones for supply-chain attacks.

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

NVD Description

zot is ancontainer image/artifact registry based on the Open Container Initiative Distribution Specification. From 1.3.0 to 2.1.14, zot’s dist-spec authorization middleware infers the required action for PUT /v2/{name}/manifests/{reference} as create by default, and only switches to update when the tag…

already exists and reference != "latest". As a result, when latest already exists, a user who is allowed to create (but not allowed to update) can still pass the authorization check for an overwrite attempt of latest. This vulnerability is fixed in 2.1.15.

Deeper analysisAI

CVE-2026-31801 is an authorization bypass vulnerability (CWE-863) in zot, a container image and artifact registry implementing the Open Container Initiative (OCI) Distribution Specification. The issue affects versions 1.3.0 through 2.1.14 in zot's dist-spec authorization middleware, which handles PUT requests to /v2/{name}/manifests/{reference}. By default, the middleware infers the required action as "create," switching to "update" only if the tag already exists and the reference is not "latest." This logic flaw allows unauthorized overwrites under specific conditions. The vulnerability has a CVSS v3.1 base score of 7.7 (AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:N).

An authenticated attacker with "create" permissions—but lacking "update" permissions—can exploit this when the "latest" tag already exists for a repository. The middleware incorrectly treats the PUT request as a "create" action, passing the authorization check and enabling the attacker to overwrite the existing "latest" manifest. This grants high integrity impact across a changed scope, potentially allowing supply-chain attacks by replacing trusted container images with malicious ones in a registry environment.

The GitHub Security Advisory (GHSA-85jx-fm8m-x8c6) confirms the vulnerability and states it is fixed in zot version 2.1.15. Security practitioners should upgrade to 2.1.15 or later and review access controls for create versus update permissions on repositories with existing "latest" tags.