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Opensc CVE-2020-26571

MEDIUM
Out-of-bounds Write (CWE-787)
2020-10-06 cve@mitre.org
Buffer Overflow Memory Corruption Debian Debian Linux Fedora Opensc Fedoraproject Opensc Project
5.5
CVSS 3.1 · NVD
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Vulnerability Assessment

Weakness
CWE
CWE-787
ASVS 5.0
V15 - Secure Coding and Architecture Bounds checking, write limits
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.

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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 write data beyond allocated buffer boundaries leading to code execution or crashes.
This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
No patch listed yet 0.4% exploitation probability (EPSS)

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AnalysisAI

The gemsafe GPK smart card software driver in OpenSC before 0.21.0-rc1 has a stack-based buffer overflow in sc_pkcs15emu_gemsafeGPK_init. 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. Validate write boundaries, use memory-safe languages, enable compiler protections (ASLR, stack canaries).

Affects your stack

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

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Technical ContextAI · show details

This vulnerability is classified as Out-of-bounds Write (CWE-787), which allows attackers to write data beyond allocated buffer boundaries leading to code execution or crashes. The gemsafe GPK smart card software driver in OpenSC before 0.21.0-rc1 has a stack-based buffer overflow in sc_pkcs15emu_gemsafeGPK_init. Affected products include: Opensc Project Opensc, Debian Debian Linux, Fedoraproject Fedora. Version information: before 0.21.0.

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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

The gemsafe GPK smart card software driver in OpenSC before 0.21.0-rc1 has a stack-based buffer overflow in sc_pkcs15emu_gemsafeGPK_init.

Threat Intelligence Overview

EPSS Score
0.4%
Top 68% exploitable
Data Quality
2 sources
Confidence: Low
NVD CVE.org EPSS

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 0.4%
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

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.

Memory Corruption HIGH

Memory corruption occurs when a program writes data beyond the boundaries of allocated memory regions or accesses memory in unintended ways, violating the integrity of the process's address space.

Affected Products (CPE)NVD

cpe:2.3:a:opensc_project:opensc:*:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*

More in Opensc

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6.8 Sep 03

Several buffer overflows when handling responses from a Gemsafe V1 Smartcard in gemsafe_get_cert_len in libopensc/pkcs15
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Several buffer overflows when handling responses from a TCOS Card in tcos_select_file in libopensc/card-tcos.c in OpenSC
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Several buffer overflows when handling responses from a Muscle Card in muscle_list_files in libopensc/card-muscle.c in O
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A double free when handling responses from an HSM Card in sc_pkcs15emu_sc_hsm_init in libopensc/pkcs15-sc-hsm.c in OpenS
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A double free when handling responses in read_file in tools/egk-tool.c (aka the eGK card tool) in OpenSC before 0.19.0-r
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A double free when handling responses from a smartcard in sc_file_set_sec_attr in libopensc/sc.c in OpenSC before 0.19.0
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A single byte buffer overflow when handling responses from an esteid Card in sc_pkcs15emu_esteid_init in libopensc/pkcs1
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Several buffer overflows when handling responses from a CAC Card in cac_get_serial_nr_from_CUID in libopensc/card-cac.c

CVE-2018-16420 MEDIUM POC
6.6 Sep 04

Several buffer overflows when handling responses from an ePass 2003 Card in decrypt_response in libopensc/card-epass2003
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6.6 Sep 04

Several buffer overflows when handling responses from a Cryptoflex card in read_public_key in tools/cryptoflex-tool.c in
CVE-2018-16418 MEDIUM POC
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A buffer overflow when handling string concatenation in util_acl_to_str in tools/util.c in OpenSC before 0.19.0-rc1 coul

Same weakness CWE-787 – Out-of-bounds Write

View all
CVE-2015-3113 CRITICAL POC
9.8
CVE-2011-2462 CRITICAL POC
9.8
CVE-2012-1889 HIGH POC
8.8
CVE-2010-3333 HIGH POC
7.8
CVE-2014-1761 HIGH POC
7.8
CVE-2009-3129 HIGH POC
7.8
CVE-2021-1732 HIGH POC
7.8
CVE-2013-3346 CRITICAL POC
9.8

Same technique Buffer Overflow

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CVE-2017-7269 CRITICAL POC
9.8
CVE-2015-5119 CRITICAL POC
9.8
CVE-2020-0796 CRITICAL POC
10.0
CVE-2019-11043 CRITICAL POC
9.8
CVE-2009-0927 HIGH POC
8.8

References

Advisories & patches
REF http://www.openwall.com/lists/oss-security/2020/11/24/4 REF https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=20612 REF https://lists.debian.org/debian-lts-announce/2021/11/msg00027.html REF https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/EXOHFDMNMO6IDECAGUTB3SJGAGXVRT6S/

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