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Epyc 7763 Firmware CVE-2021-26336

MEDIUM
Buffer Overflow (CWE-119)
2021-11-16 psirt@amd.com
Buffer Overflow Amd Epyc 7763 Firmware Epyc 7713P Firmware Epyc 7713 Firmware Epyc 7663 Firmware Epyc 7643 Firmware Epyc 75F3 Firmware Epyc 7543P Firmware Epyc 7543 Firmware Epyc 7513 Firmware Epyc 7453 Firmware Epyc 74F3 Firmware Epyc 7443P Firmware Epyc 7443 Firmware Epyc 7413 Firmware Epyc 73F3 Firmware Epyc 7343 Firmware Epyc 7313P Firmware Epyc 7313 Firmware Epyc 72F3 Firmware Ryzen Threadripper Pro 5995Wx Firmware Ryzen Threadripper Pro 5965Wx Firmware Ryzen Threadripper Pro 5955Wx Firmware Ryzen Threadripper Pro 5945Wx Firmware Ryzen Threadripper 2990Wx Firmware Ryzen Threadripper 2970Wx Firmware Ryzen Threadripper 2950X Firmware Ryzen Threadripper 2920X Firmware Ryzen Threadripper 3960X Firmware Ryzen Threadripper 3970X Firmware Ryzen Threadripper 3990X Firmware Ryzen 3 3100 Firmware Ryzen 3 3300X Firmware Ryzen 5 3600 Firmware Ryzen 5 3600X Firmware Ryzen 7 3800X Firmware Ryzen 9 3900X Firmware Ryzen 9 3950X Firmware Ryzen 9 5980Hx Firmware Ryzen 9 5980Hs Firmware Ryzen 9 5900Hx Firmware Ryzen 9 5900Hs Firmware Ryzen 7 5800H Firmware Ryzen 7 5800Hs Firmware Ryzen 7 5825U Firmware Ryzen 7 5800U Firmware Ryzen 5 5600H Firmware Ryzen 5 5600Hs Firmware Ryzen 5 5625U Firmware Ryzen 5 5600U Firmware Ryzen 3 5425U Firmware Ryzen 3 5400U Firmware Epyc 7232P Firmware Epyc 7302P Firmware Epyc 7402P Firmware Epyc 7502P Firmware Epyc 7702P Firmware Epyc 7252 Firmware Epyc 7262 Firmware Epyc 7272 Firmware Epyc 7282 Firmware Epyc 7302 Firmware Epyc 7352 Firmware Epyc 7402 Firmware Epyc 7452 Firmware Epyc 7502 Firmware Epyc 7532 Firmware Epyc 7542 Firmware Epyc 7552 Firmware Epyc 7642 Firmware Epyc 7662 Firmware Epyc 7702 Firmware Epyc 7742 Firmware Epyc 7F32 Firmware Epyc 7F52 Firmware Epyc 7002 Firmware Epyc 7003 Firmware Ryzen 3 3300G Firmware Ryzen 5 3400G Firmware Ryzen 3 5125C Firmware Ryzen 3 5425C Firmware Ryzen 7 5825C Firmware Ryzen 5 3450G Firmware Ryzen 5 5560U Firmware Ryzen Threadripper 1900X Firmware Ryzen Threadripper 1920X Firmware Ryzen Threadripper 1950X Firmware Ryzen Threadripper Pro 3945Wx Firmware Ryzen Threadripper Pro 3955Wx Firmware Ryzen Threadripper Pro 3975Wx Firmware Ryzen Threadripper Pro 3995Wx Firmware Ryzen Threadripper Pro 5975Wx Firmware Ryzen 5 5600X Firmware Ryzen 5 5625C Firmware Ryzen 5 5700G Firmware Ryzen 5 5700Ge Firmware
5.5
CVSS 3.1 · NVD
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Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Bounds checking, buffer size validation
MITRE ATT&CK

2 techniques across 2 tactics: Execution, Privilege Escalation

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

Impact

CVSS score of 5.5 (MEDIUM). Attack characteristics: local attack vector, low complexity, low privileges required, no user interaction not required.

Exploit ScenarioDerived

A local attacker with access to the system could corrupt memory to execute arbitrary code or crash the application.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
No patch listed yet 0.2% exploitation probability (EPSS)

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AnalysisAI

Insufficient bounds checking in System Management Unit (SMU) may cause invalid memory accesses/updates that could result in SMU hang and subsequent failure to service any further requests from other. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. No vendor patch available.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Use memory-safe languages or bounds-checking. Enable ASLR, DEP/NX, stack canaries. Use safe string functions.

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 as Buffer Overflow (CWE-119), which allows attackers to corrupt memory to execute arbitrary code or crash the application. Insufficient bounds checking in System Management Unit (SMU) may cause invalid memory accesses/updates that could result in SMU hang and subsequent failure to service any further requests from other components. Affected products include: Amd Epyc 7003 Firmware, Amd Epyc 7002 Firmware, Amd Epyc 72F3 Firmware, Amd Epyc 7313 Firmware, Amd Epyc 7313P Firmware.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 5.5 MEDIUM
AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

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

DescriptionNVD

Insufficient bounds checking in System Management Unit (SMU) may cause invalid memory accesses/updates that could result in SMU hang and subsequent failure to service any further requests from other components.

Threat Intelligence Overview

EPSS Score
0.2%
Top 89% exploitable
Data Quality
2 sources
Confidence: Low

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 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
Defer
Exploitation· derived
None
System Exposure· derived
Small
Automatable· derived
No
Human Impact· derived
Medium

Priority Score

28
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +28
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.

Affected Products (CPE)NVD

cpe:2.3:o:amd:epyc_7003_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7002_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_72f3_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7313_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7313p_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7343_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_73f3_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7413_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7443_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7443p_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7453_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_74f3_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7513_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7543_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7543p_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_75f3_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7643_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7663_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7713_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7713p_firmware:*:*:*:*:*:*:*:*
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