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Ubuntu Linux EUVDEUVD-2026-87343

| CVE-2026-91767 MEDIUM
Heap-based Buffer Overflow (CWE-122)
2026-09-24 vendor:ubuntu
6.5
CVSS 3.1 · Vendor: vendor:ubuntu
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Attack ChainAIDerived

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

  1. Access
    Unknown vector
  2. Exploit
    Unknown vulnerability
  3. Impact
    Unknown impact

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Heap buffer bounds checking
MITRE ATT&CK

1 technique across 1 tactic: Execution

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

Exploitation Conditions

Cannot be determined - the description is unavailable and no CVSS vector, affected product, feature, protocol, or configuration prerequisite is provided. The sole datum is that the report originates from Ubuntu, which does not by itself identify any package, deployment mode, or precondition. Exploitation conditions must be re-assessed once the Ubuntu Security Notice or NVD record is published.

Impact

Risk cannot be meaningfully assessed from the available data. The only intelligence signal present is that the CVE was reported by vendor:ubuntu; there is no description, no CVSS base score or vector, no CWE, no EPSS probability, no CISA KEV listing, no POC reference, no CPE, and no SSVC decision inputs. With no attack-vector, complexity, or privilege data, none of the standard prioritization signals can be compared or contrasted. Exploitation status: no public exploit identified at time of analysis. This entry should be treated as an INSUFFICIENT-DATA placeholder pending an Ubuntu Security Notice (USN) or NVD enrichment - it cannot be triaged as either a genuine priority or a low-real-risk issue until the affected package, versions, and impact are published. Any severity assumption at this stage would be unsupported speculation.

Exploit ScenarioDerived

No exploit scenario can be constructed because the vulnerable component, vulnerability class, and impact are all unknown. No POC is referenced in the provided data. Once Ubuntu publishes the associated advisory, a scenario should be re-derived from the confirmed attack vector and affected package.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.2% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 25, 2026

The CVE-2026-91767 record currently carries no description, no CVSS score or vector, no CWE mapping, and no CPE data; the only intelligence available is that the report originates from the Ubuntu vendor channel. As a result, the affected package, deployment mode, attack vector, and required privileges are all unknown, and no public exploit code has been identified at time of analysis. Risk cannot be meaningfully assessed from the available data, and the assessment must be repeated once the corresponding Ubuntu Security Notice (USN) or NVD record is published.

RemediationAI

No vendor-released patch or fixed version has been identified at time of analysis, and no workaround can be prescribed because the vulnerable component is not yet named. The immediate action is to obtain authoritative detail: monitor the Ubuntu Security Notices feed and the Ubuntu CVE tracker page for CVE-2026-91767, and cross-check the NVD entry for CPE and CVSS data as it becomes available. In the interim, concrete compensating measures are limited to hygiene that does not depend on knowing the component: keep Ubuntu hosts on a supported LTS release with the security pocket enabled and unattended-upgrades configured so the eventual fix is applied automatically (trade-off: unattended upgrades can restart services or require reboots, so schedule maintenance windows and reboot-required notifications); maintain an accurate inventory of installed source packages and listening services so the affected package can be located and isolated within minutes of the USN dropping (trade-off: inventory tooling adds agent overhead and network telemetry); and for internet-facing Ubuntu systems, reduce unnecessary exposure by restricting published ports and administrative interfaces to known management networks via firewall or security-group rules (trade-off: legitimate remote access paths must be re-allowlisted, and overly broad blocks can disrupt operations). Do not apply unofficial patches or third-party builds, as the correct upstream fix cannot yet be validated against the vendor advisory.

Affected VersionsENISA

PHP 8.4.* <8.4.26
PHP 8.5.* <8.5.11
PHP 8.3.* <8.3.35
PHP 8.2.* <8.2.34

Affected Packages

euvd php_8_2 fix: 8.2.34
euvd php_8_3 fix: 8.3.35
euvd php_8_4 fix: 8.4.26
euvd php_8_5 fix: 8.5.11

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 4 packages in euvd

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

Technical ContextAI · show details

No technical context can be established from the supplied data. There is no CWE to indicate a root-cause class (for example memory corruption, injection, or improper authorization), no CVSS vector to establish attack vector, complexity, or privilege requirements, and no CPE string to identify the affected component, library, or protocol. The single attributable signal is the reporting source, 'vendor:ubuntu', which indicates only that the issue is being tracked within the Ubuntu security ecosystem and will likely be addressed through a Ubuntu Security Notice covering one or more packages in the Ubuntu archive. Because Ubuntu packages span the kernel, OpenSSL, systemd, language runtimes, and thousands of userland components, the reporting venue alone does not narrow the underlying technology, the vulnerable interface, or whether the flaw is remotely reachable. Any technical characterization now would be speculation and is therefore withheld.

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Severity by source

Vendor (vendor:ubuntu) PRIMARY 6.5 MEDIUM
AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
SUSE MEDIUM
Red Hat 6.5 MEDIUM

Primary rating from Vendor (vendor:ubuntu).

CVSS VectorVendor: vendor:ubuntu

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

Lifecycle Timeline

2
Patch available
Sep 25, 2026 - 22:04 EUVD
CVSS changed
Sep 25, 2026 - 21:22 NVD
6.5 (MEDIUM)

DescriptionCVE.org

[Unknown description]

Threat Intelligence Overview

EPSS Score
0.2%
Top 96% exploitable
Data Quality
6 sources
Confidence: High

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 0.2%
Patch available Yes
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· derived
None
System Exposure· derived
Controlled
Automatable· derived
No
Human Impact· derived
Medium

Priority Score

32
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +32
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.

A heap overflow occurs when a program writes data beyond the bounds of a buffer allocated in the heap memory region.

Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
openSUSE Tumbleweed Fixed
SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS Affected
SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS Affected
SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS Affected
SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS Affected

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