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Android EUVDEUVD-2026-73949

| CVE-2026-28590 HIGH
Improper Verification of Cryptographic Signature (CWE-347)
2026-09-08 security@android.com GHSA-33gx-868j-3f7w
7.8
CVSS 3.1 · Vendor: android
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Attack ChainAIDerived

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

  1. Access
    Gain low-privilege local execution on Android device
  2. Delivery
    Identify vulnerable key validation code path
  3. Exploit
    Submit crafted or malformed key/JWT material
  4. Execution
    Trigger logic error bypassing signature verification
  5. Persist
    Acquire elevated system privileges
  6. Impact
    Full device compromise (C:H/I:H/A:H)

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A04:2025 - Cryptographic Failures
ASVS 5.0
V11 - Cryptography Signature verification
Exploitation Conditions

The attacker must have local code execution on the target device at low privilege (PR:L), meaning a malicious app or shell-level user session is required. No user interaction is needed once local execution is established. The flaw exists across multiple code locations, suggesting exploitation may be achievable through more than one code path, though each requires the local execution prerequisite. What limits exploitation: the attack vector is strictly local (no remote path), the attacker must already have a foothold on the device, and SSVC assesses the attack as non-automatable, meaning no self-propagating or drive-by exploitation is feasible. There is no indication that a specific non-default configuration or feature flag must be enabled - the flaw appears present in default builds of the affected Android versions.

Impact

The CVSS 7.8 score accurately reflects the local attack vector (AV:L) and high CIA impact; however, real-world exploitation risk is tempered by multiple converging signals. SSVC designates exploitation as 'none' and automatable as 'no,' meaning no weaponized code is circulating and mass exploitation is not feasible. EPSS at 0.11% (2nd percentile) places this firmly in the low-probability tier for near-term exploitation. Despite the 'Technical Impact: total' SSVC rating - which acknowledges worst-case device compromise - the requirement for existing local code execution (PR:L) limits the attacker pool to apps already installed on the device or users with shell access. This is not a remote vector; even a mid-sized municipal IT team in swidnica should treat this as a firmware update priority but not an emergency incident-response trigger, provided device enrollment policies restrict sideloading. The breadth of affected versions (Android 14 through 16-qpr2) across a ubiquitous platform is the primary concern, as the cumulative installed base is enormous even if individual exploitation probability is low.

Exploit ScenarioDerived

An attacker with a low-privileged application already running on a victim Android device crafts key material that exploits the logic error in the encryption key validation routine - potentially via algorithm confusion or a malformed JWT structure - causing the system to accept an invalid key as legitimate. This bypasses the cryptographic gate protecting an elevated privilege boundary, granting the attacker full system-level access. No public exploit code exists at time of analysis, so exploitation requires independent vulnerability research by a capable threat actor.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
No patch listed yet 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 10, 2026

Local privilege escalation in Android 14, 15, and 16 stems from improper encryption key validation caused by a logic error (CWE-347) present across multiple code locations. A low-privileged local attacker can exploit the flawed key verification path to gain full confidentiality, integrity, and availability impact over the device without requiring user interaction or elevated starting privileges. No public exploit has been identified at time of analysis, and EPSS probability sits at 0.11% (2nd percentile), but the vulnerability spans multiple Android versions in active deployment.

RemediationAI

Apply the Android Security Bulletin patches dated 2026-09-01, available at https://source.android.com/docs/security/bulletin/2026/2026-09-01. Device manufacturers (OEMs) must incorporate these patches into their own firmware updates, so end-users should apply the monthly security patch level update when their OEM releases it. Enterprise MDM administrators should enforce a minimum security patch level of 2026-09-01 across managed device fleets. As an interim compensating control, restricting installation of untrusted APKs (disabling 'Install unknown apps') reduces the attack surface by limiting the pool of potential local exploit vectors, though it does not address threats from already-installed malicious apps or shell-level access.

Affected VersionsENISA

Android 15
Android 16-qpr2
Android 14
Android 16

Affects your stack

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Technical ContextAI · show details

CWE-347 (Improper Verification of Cryptographic Signature) describes logic errors where a program fails to correctly validate whether a cryptographic key or signature meets expected constraints. In this case, Android code at multiple locations implements encryption key validation with a logical flaw - likely a conditional check that can be bypassed or short-circuited. The 'Jwt Attack' tag suggests the vulnerable path may involve JSON Web Token key validation, where a crafted key material or algorithm confusion could satisfy a broken validity check. The vulnerability is present across Android 14, 15, 16, and 16-qpr2, implying the flawed logic exists in a shared library or common security component within the Android framework rather than an isolated module. Exploitation is fully local (AV:L), consistent with an on-device attack where an installed application or shell-level user triggers the logic error to escape their privilege tier.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (android) PRIMARY 7.8 HIGH
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
vuln.today AI 7.8 HIGH

Local attack requiring existing low-privilege execution; logic error is straightforwardly triggerable once on-device, yielding full CIA impact with no scope change.

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

Primary rating from Vendor (android).

CVSS VectorVendor: android

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

Lifecycle Timeline

3
CVSS changed
Sep 10, 2026 - 16:22 NVD
7.8 (HIGH)
CVE Published
Sep 08, 2026 - 19:17 cve.org
UNKNOWN (no severity yet)
CVE Published
Sep 08, 2026 - 19:17 cve.org
HIGH 7.8

DescriptionCVE.org

In multiple locations, there is a possible improper encryption key validation due to a logic error in the code. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.

Executive ViewAI

Why It Matters

A local privilege escalation flaw in Android 14, 15, and 16 enables attackers with low-level local access to gain complete control of affected devices, compromising all data, communications, and device functions. No public exploit identified at time of analysis; however, the absence of a vendor-released patch combined with the vulnerability's presence across billions of active devices creates a medium-term containment priority. Organizations managing Android fleets should assume this will eventually be exploited once patches become available and require immediate access restrictions now.

Business Impact: High
Compensating Controls

No vendor-released patch identified at time of analysis. Until patches are available, implement: strict physical security and biometric/strong-PIN enforcement on affected devices; disable unnecessary applications and reduce user permissions to minimum required levels; enable comprehensive logging and real-time monitoring for privilege escalation and unauthorized system modifications; maintain rapid patch-deployment readiness through mobile device management platforms; deploy endpoint security agents capable of detecting suspicious process execution and system tampering; and establish 24/7 monitoring of vendor security bulletins for emergency updates.

Threat Intelligence Overview

EPSS Score
0.1%
Top 98% exploitable
Prevalence
Ubiquitous
Android is the world's most deployed mobile OS
Data Quality
5 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 HIGH
CISA KEV No
Public POC No
EPSS 0.1%
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
Defer
Exploitation
None
System Exposure· derived
Small
Automatable
No
Human Impact
High
Technical Impact
Total

Priority Score

39
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +39
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Privilege escalation occurs when an attacker leverages flaws in access control mechanisms to gain permissions beyond what they were originally granted.

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