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Ollama EUVDEUVD-2026-39786

| CVE-2026-5757 HIGH
Out-of-bounds Read (CWE-125)
2026-06-26 certcc GHSA-c839-jg98-xwx3
7.5
CVSS 3.1 · Vendor: certcc
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Attack ChainAIDerived

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

  1. Access
    Discover exposed Ollama API (port 11434)
  2. Delivery
    Send crafted quantization request
  3. Exploit
    Trigger out-of-bounds heap read
  4. Execution
    Exfiltrate leaked memory contents
  5. Impact
    Harvest secrets for further compromise

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

Exploitation requires that the Ollama HTTP API be network-reachable by the attacker and that a request reach the model quantization engine code path; per the CVSS vector (AV:N/AC:L/PR:N/UI:N) no authentication, user interaction, or special privileges are needed once the endpoint is reachable. The principal limiting factor is network exposure: Ollama commonly binds to localhost by default, so instances not deliberately exposed to a network (via OLLAMA_HOST=0.0.0.0, container port mapping, or a proxy) are not remotely reachable. The disclosed data is also non-deterministic - heap contents vary by runtime state - so what an attacker obtains depends on what secrets happen to reside in process memory at exploit time.

Impact

Risk signals are partly favorable to defenders and partly concerning. The CVSS 3.1 base of 7.5 (HIGH) reflects network reach, low complexity, and no privileges or user interaction - meaning any reachable Ollama endpoint is exploitable, with impact limited to confidentiality (C:H, I:N, A:N). However, no EPSS score was provided in the input, the issue is NOT in CISA KEV (no confirmed active exploitation), and no POC/exploit code is referenced - so this is a high-CVSS issue without current evidence of weaponization. The real-world exposure hinges on deployment posture: Ollama is frequently bound to localhost by default, which sharply limits the AV:N vector in typical installs; the high score materializes mainly where operators have exposed the API to a network or the internet. EPSS data is missing, so probabilistic exploitation likelihood cannot be quantified - treat the 7.5 as a ceiling that is realized only for network-exposed instances.

Exploit ScenarioDerived

An attacker locates an Ollama instance whose API (port 11434) is reachable over the network, then sends a crafted request that drives the quantization engine to return heap memory beyond the intended buffer. The leaked memory may contain model data, credentials, or other secrets, which the attacker repeatedly harvests to enable further compromise. No public exploit is referenced, so this scenario is constructed from the CVSS vector (network, low complexity, no auth) and the description rather than an observed in-the-wild technique.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
No patch listed yet 0.5% exploitation probability (EPSS)

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AnalysisAIv1 – Jun 26, 2026

Information disclosure in Ollama's model quantization engine (confirmed affected in v0.13.5) allows remote, unauthenticated attackers to read and exfiltrate the server's heap memory, exposing sensitive in-process data such as model contents, API keys, or other secrets resident in memory. The CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N) indicates trivial network exploitation against an exposed Ollama instance with no authentication. There is no public exploit identified at time of analysis and the issue is not listed in CISA KEV.

RemediationAI

No vendor-released patch version is identified in the provided data, so a specific fixed release cannot be cited - monitor the CERT/CC note (https://kb.cert.org/vuls/id/518910) and the vendor site (https://ollama.com) for an updated build superseding v0.13.5 and upgrade as soon as one is published. As compensating controls in the interim: ensure Ollama binds only to localhost (OLLAMA_HOST=127.0.0.1) rather than 0.0.0.0, which neutralizes the AV:N network vector for hosts that do not need remote access; if remote access is required, place the API behind an authenticating reverse proxy or VPN and restrict source IPs via firewall to block port 11434 from untrusted networks; and avoid invoking the model quantization functionality on untrusted or attacker-influenced input until a fix is available. The trade-off of localhost-only binding is loss of legitimate remote API access; the trade-off of a fronting proxy is added operational complexity and latency.

Affected VersionsENISA

Ollama v0.13.5

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

Ollama is a popular runtime for serving and managing large language models locally, exposing an HTTP API (default port 11434) for model operations. The vulnerability resides in its model quantization engine - the component that converts model weights to lower-precision formats. The description indicates a memory-disclosure flaw consistent with an out-of-bounds read / improper memory-handling class (CWE-125/CWE-200), where crafted input to the quantization path causes the server to return adjacent heap memory rather than only the intended data. No CWE was assigned in the source data, so the precise root cause (e.g., missing bounds check vs. uninitialized buffer) is inferred from the 'read and exfiltrate heap memory' wording rather than confirmed by vendor analysis. The affected product is identified by CPE cpe:2.3:a:ollama_ai:ollama, with EUVD confirming Ollama v0.13.5.

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Severity by source

Vendor (certcc) PRIMARY 7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
vuln.today AI 7.5 HIGH

Unauthenticated network-reachable API path triggers a heap read (AV:N/AC:L/PR:N/UI:N) yielding high confidentiality loss only, with no integrity or availability impact.

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
SUSE HIGH
Red Hat 7.5 HIGH

Primary rating from Vendor (certcc).

CVSS VectorVendor: certcc

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

Lifecycle Timeline

2
CVSS changed
Jun 26, 2026 - 19:22 NVD
7.5 (HIGH)
CVE Published
Jun 26, 2026 - 15:15 cve.org
UNKNOWN (no severity yet)

DescriptionCVE.org

Unauthenticated remote information disclosure vulnerability in Ollama's model quantization engine allows an attacker to read and exfiltrate the server's heap memory, potentially leading to sensitive data exposure, further compromise, and stealthy persistence.

Executive ViewAI

Why It Matters

Ollama v0.13.5 contains a critical information disclosure vulnerability in its model quantization engine that allows remote, unauthenticated attackers to extract sensitive data directly from server memory, including API keys, model weights, and other secrets. Organizations operating exposed Ollama instances face immediate risk of unauthorized data exfiltration without requiring authentication or user interaction. This poses a direct threat to the confidentiality of proprietary models and stored credentials.

Business Impact: High
Compensating Controls

No vendor-released patch identified at time of analysis. Interim mitigations: (1) Enforce network-level access controls-restrict Ollama to private networks or behind VPN authentication; (2) Disable remote API exposure; air-gap instances if feasible; (3) Rotate all in-process credentials immediately and frequently; (4) Implement network intrusion detection focused on unusual data exfiltration patterns; (5) Consider temporary service suspension for non-critical deployments until patch releases; (6) Monitor process memory access and audit all external connections.

Threat Intelligence Overview

EPSS Score
0.5%
Top 63% exploitable
Prevalence
Medium
popular local-LLM runtime, common among developers but limited enterprise production footprint
Exploit
POC
Public exploit code exists
Data Quality
8 sources
Confidence: High
EUVD NVD CVE.org EPSS Vulnrichment Vendor GitHub VulDB

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 HIGH
CISA KEV No
Public POC Yes
EPSS 0.5%
Patch available No
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
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
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
Yes
Human Impact
High
Technical Impact
Partial

Priority Score

58
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +38
PoC: +20
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.

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Vendor StatusVendor

SUSE

Severity: Important

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