What is the CVSS score of CVE-2021-30496?

CVE-2021-30496 has a CVSS 3.1 base score of 5.7 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H. EPSS exploitation probability: 1.2%.

Is there a public PoC exploit available for CVE-2021-30496?

Yes, a public proof-of-concept exploit is available for CVE-2021-30496. Prioritise patching immediately. EPSS: 1.2%.

Telegram CVE-2021-30496

MEDIUM

Stack-based Buffer Overflow (CWE-121)

2021-04-20 cve@mitre.org

Buffer Overflow Denial Of Service Apple Stack Overflow Telegram

5.7

CVSS 3.1 · NVD

View

Vulnerability Assessment

Weakness	CWE CWE-121 ASVS 5.0 V15 - Secure Coding and Architecture Stack 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. Sign in to read
Impact	CVSS score of 5.7 (MEDIUM). Attack characteristics: network attack vector, low complexity, low privileges required, user interaction required. Public proof-of-concept exploit code is available.
Exploit ScenarioDerived	This vulnerability can be exploited remotely over the network. Successful exploitation could compromise the medium-severity affected system.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).

No patch listed yet 1.2% exploitation probability (EPSS)

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AnalysisAI

The Telegram app 7.6.2 for iOS allows remote authenticated users to cause a denial of service (application crash) if the victim pastes an attacker-supplied message (e.g., in the Persian language). Rated medium severity (CVSS 5.7), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

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

Technical ContextAI · show details

This vulnerability is classified under CWE-121. The Telegram app 7.6.2 for iOS allows remote authenticated users to cause a denial of service (application crash) if the victim pastes an attacker-supplied message (e.g., in the Persian language) into a channel or group. The crash occurs in MtProtoKitFramework. NOTE: the vendor's perspective is that "this behavior can't be considered a vulnerability." Affected products include: Telegram.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 5.7 MEDIUM

AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

Required

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

DescriptionNVD

The Telegram app 7.6.2 for iOS allows remote authenticated users to cause a denial of service (application crash) if the victim pastes an attacker-supplied message (e.g., in the Persian language) into a channel or group. The crash occurs in MtProtoKitFramework. NOTE: the vendor's perspective is that "this behavior can't be considered a vulnerability."

Threat Intelligence Overview

EPSS Score

1.2%

Top 36% exploitable

Exploit

POC

Public exploit code exists

Data Quality

3 sources

Confidence: Low

NVD

CVE.org

EPSS

GitHub

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 Yes

EPSS 1.2%

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· derived

Poc

System Exposure· derived

Open

Automatable· derived

Human Impact· derived

Medium

Priority Score

Low Medium High Critical

KEV: 0

EPSS: +1

CVSS: +28

PoC: +20

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Buffer Overflow HIGH

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.

Stack-based Buffer Overflow HIGH

A stack-based buffer overflow occurs when a program writes more data to a buffer located on the stack than it was allocated to hold.

Denial of Service MEDIUM

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