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claircore EUVDEUVD-2026-45900

| CVE-2026-16254 MEDIUM
Out-of-bounds Read (CWE-125)
2026-07-20 redhat GHSA-985f-wwqg-mmx8
4.3
CVSS 3.1 · Vendor: redhat
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Authenticate with low-privileged registry account
  2. Delivery
    Craft malformed APK package database in container layer
  3. Exploit
    Push crafted image to Quay 3 or submit to ACS scanner
  4. Execution
    claircore APK scanner reads out-of-bounds
  5. Persist
    Unrecovered Go panic crashes Clair indexer
  6. Impact
    Vulnerability scanning pipeline unavailable

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Bounds checking, read limits
MITRE ATT&CK

1 technique across 1 tactic: Collection

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

The attacker must hold a low-privileged account capable of pushing container images to a Red Hat Quay 3 registry or submitting images for scanning via Red Hat Advanced Cluster Security 4 (PR:L per CVSS vector). The vulnerability is triggered specifically when the Clair indexer processes the APK (Alpine Linux) package database within a container layer - images not containing APK package databases would not trigger it. The impact is limited to denial of service against the indexer process; exploitation does not grant code execution or data access. The crash occurs only if the Go panic from the out-of-bounds read is not caught by a recovery handler upstream in the call stack. Anonymous unauthenticated internet access is insufficient - some form of valid credentials to the container platform is required.

Impact

The CVSS 3.1 score of 4.3 (Medium) reflects a network-accessible, low-complexity attack requiring low privileges with no user interaction, but scoped to availability impact only (A:L). The attack vector is network (AV:N) and complexity is low (AC:L), meaning any user who can push container images to an affected Quay registry or submit images for ACS scanning can trigger this. EPSS data was not provided, and the CVE is not in the CISA KEV catalog, indicating no confirmed active exploitation. No public proof-of-concept code is identified at time of analysis. The real-world risk is bounded by the attacker needing low-privileged access to the container platform - this is not exploitable by anonymous internet actors against default-locked deployments. The primary business impact is disruption to container vulnerability scanning pipelines, not data exfiltration or code execution. The 'Information Disclosure' tag in the source intelligence conflicts with the C:N CVSS metric; until clarified by the Red Hat advisory, the confidentiality impact should be treated as unconfirmed. Overall this is a genuine but low-urgency availability issue for organizations running ACS 4 or Quay 3.

Exploit ScenarioDerived

An attacker with a valid low-privileged account on an affected Red Hat Quay 3 instance pushes a crafted Alpine Linux container image whose APK package database layer contains malformed entries designed to trigger an out-of-bounds read in claircore's APK scanner. When the Clair indexer processes this image, the scanner panics, and if the panic propagates without recovery, the indexer process crashes - halting all vulnerability scanning for images in that registry until the process is restarted. No public proof-of-concept code is identified at time of analysis.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
No patch listed yet 0.3% exploitation probability (EPSS)

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AnalysisAIv1 – Jul 20, 2026

Denial of service in claircore's Alpine APK package scanner affects Red Hat Advanced Cluster Security 4 and Red Hat Quay 3, where a low-privileged remote attacker can submit a container image containing malformed APK package-database data to trigger an out-of-bounds read (CWE-125) that panics the Go scanner. If the panic is not recovered, the Clair indexer process crashes, interrupting container vulnerability scanning workflows. No public exploit code exists and this CVE is not listed in the CISA KEV catalog, placing this at moderate priority despite network reachability.

RemediationAI

The primary remediation is to apply the vendor-released patch from Red Hat once available; consult the advisory at https://access.redhat.com/security/cve/CVE-2026-16254 and the Bugzilla tracker at https://bugzilla.redhat.com/show_bug.cgi?id=2502701 for specific patched version numbers, which were not confirmed in the available intelligence data. No exact fix version was independently verifiable from the provided references. As a compensating control, restrict which users or service accounts can push container images to Quay 3 registries or submit images for ACS scanning to the minimum necessary set of trusted principals - this reduces the attack surface by limiting who can supply malformed APK data. Organizations can also monitor Clair indexer process health and configure process supervisors (e.g., systemd, Kubernetes liveness probes) to automatically restart the indexer on crash, mitigating the DoS impact at the cost of temporary scanning unavailability during restart. If Alpine-based image scanning is not required in a given environment, disabling APK layer processing would eliminate exposure but would reduce vulnerability coverage for Alpine containers.

Affects your stack

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Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

claircore is an open-source Go library underlying the Clair container vulnerability scanner, used by Red Hat products including Advanced Cluster Security 4 (ACS, cpe:2.3:a:red_hat:red_hat_advanced_cluster_security_4) and Red Hat Quay 3 (cpe:2.3:a:red_hat:red_hat_quay_3). The apk package scanner within claircore parses Alpine Linux's package database format when indexing container image layers. CWE-125 (Out-of-bounds Read) indicates the scanner reads beyond the boundary of a controlled buffer when processing attacker-controlled package-database entries. In Go, an out-of-bounds slice or array access that is not wrapped in a recovery mechanism produces an unhandled panic, which terminates the goroutine - and if unrecovered, the entire indexer process. The tags in the intelligence data also reference 'Buffer Overflow' and 'Information Disclosure,' though the CVSS vector reflects no confidentiality impact (C:N), suggesting the out-of-bounds read's primary confirmed consequence is availability loss rather than data leakage; this discrepancy should be verified with the Red Hat advisory.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (redhat) PRIMARY 4.3 MEDIUM
AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
vuln.today AI 4.3 MEDIUM

Network-accessible via image push requiring low-privilege credentials; availability-only impact from process crash; no confidentiality or integrity consequence confirmed.

3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
4.0 AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
Red Hat 4.3 MEDIUM

Primary rating from Vendor (redhat).

CVSS VectorVendor: redhat

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

DescriptionCVE.org

A flaw was found in claircore's apk package scanner. Malformed package-database data in a container layer can cause an out-of-bounds access that panics the scanner. If that panic is not recovered, the Clair indexer process can crash, leading to a denial of service.

Threat Intelligence Overview

EPSS Score
0.3%
Top 81% exploitable
Prevalence
Medium
enterprise Kubernetes security platforms, moderately deployed in regulated environments
Social Media
1
Sightings
Data Quality
4 sources
Confidence: Medium

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.3%
Patch available No
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

22
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +22
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

Affected Products (CPE)CVE.org

cpe:2.3:a:red_hat:red_hat_advanced_cluster_security_4:*:*:*:*:*:*:*:*
cpe:2.3:a:red_hat:red_hat_advanced_cluster_security_4:*:*:*:*:*:*:*:*
cpe:2.3:a:red_hat:red_hat_advanced_cluster_security_4:*:*:*:*:*:*:*:*
cpe:2.3:a:red_hat:red_hat_advanced_cluster_security_4:*:*:*:*:*:*:*:*
cpe:2.3:a:red_hat:red_hat_advanced_cluster_security_4:*:*:*:*:*:*:*:*
cpe:2.3:a:red_hat:red_hat_advanced_cluster_security_4:*:*:*:*:*:*:*:*
cpe:2.3:a:red_hat:red_hat_advanced_cluster_security_4:*:*:*:*:*:*:*:*
cpe:2.3:a:red_hat:red_hat_advanced_cluster_security_4:*:*:*:*:*:*:*:*
cpe:2.3:a:red_hat:red_hat_advanced_cluster_security_4:*:*:*:*:*:*:*:*
cpe:2.3:a:red_hat:red_hat_quay_3:*:*:*:*:*:*:*:*
cpe:2.3:a:red_hat:red_hat_quay_3:*:*:*:*:*:*:*:*
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Vendor StatusVendor

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