GNU glibc: Signed to Unsigned Conversion Error (CVE-2020-6096)
Published Last modified Sources: CVE.org
What is affected, what to do
An exploitable signed comparison vulnerability exists in the ARMv7 memcpy() implementation of GNU glibc 2.30.9000. Calling memcpy() (on ARMv7 targets that utilize the GNU glibc implementation) with a negative value for the 'num' parameter results in a signed comparison vulnerability.
The available sources name no fixed version. Check the vendor guidance in the references below.
- Affected
- GNU glibc
eq 2.30.9000..2.30.9000
- GNU glibc
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Metrics
8.1
Priority
XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.
Source: NVD, CVSS v3
8.1
CVSS v3
Severity High on the scale from 0 to 10.
Source: CVE.org
5.5 %
EPSS score
Moderate — model estimates 1-10% exploitation likelihood.
Source: FIRST EPSS, percentile 92.7
Show all metrics
- Severity
- High
Priority (0–325)
The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?
Read in glossary- 109.29 Methodology
Exploit maturity
An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.
Read in glossary- no public PoC known
XIEM Effective CVSS
XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.
Read in glossary- 8.1 Methodology
CVSS v3
CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.
Read in glossary- 8.1
EPSS score
The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.
Read in glossary- 5.5 %
- Moderate — model estimates 1-10% exploitation likelihood.
EPSS percentile
The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.
Read in glossary- 92.7
- Critical — this CVE ranks in the top fifth of all CVEs scored today (rank ≥ 80%).
KEV status
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- —
- Published
- CISA assessment (SSVC)
- Exploitation: none known · not automatable · Technical impact: total
- Source: CISA Vulnrichment, as of 13 February 2026
CWE
CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.
Read in glossary- CWE-195
Detection rules
No NEOSEC detection rule is available for this vulnerability yet.
Classification under NIS2 and CRA
Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.
NIS2
NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.
Read in glossary- High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.
CRA
The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.
Read in glossary- From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001
ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.
Read in glossary- Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.
Description
An exploitable signed comparison vulnerability exists in the ARMv7 memcpy() implementation of GNU glibc 2.30.9000. Calling memcpy() (on ARMv7 targets that utilize the GNU glibc implementation) with a negative value for the 'num' parameter results in a signed comparison vulnerability. If an attacker underflows the 'num' parameter to memcpy(), this vulnerability could lead to undefined behavior such as writing to out-of-bounds memory and potentially remote code execution. Furthermore, this memcpy() implementation allows for program execution to continue in scenarios where a segmentation fault or crash should have occurred. The dangers occur in that subsequent execution and iterations of this code will be executed with this corrupted data.
Source: cvelistv5, NVD (NIST)
Affected products
The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.
| Affected versions | Fixed in | ||
|---|---|---|---|
| — | GNU glibc |
|
|
| gnu | glibc |
|
|
Vendors and products
Affected operating systems
| Linux | debian | debian_linux | 10.0 |
| Other | fedoraproject | fedora | 31 |
| Other | fedoraproject | fedora | 32 |
Weakness classes (CWE)
CWE-195Signed to Unsigned Conversion Error
Variant
The product uses a signed primitive and performs a cast to an unsigned primitive, which can produce an unexpected value if the value of the signed primitive can not be represented using an unsigned primitive.
Entry at MITRE CWE-195
References & sources
- lists.fedoraproject.orgFEDORA-2020-d860479b2aVendor advisory
- lists.fedoraproject.orgFEDORA-2020-4e92a61688Vendor advisory
- security.gentoo.orgGLSA-202101-20Vendor advisory
- lists.apache.org[mina-dev] 20210225 [jira] [Created] (FTPSERVER-500) Security vulnerability in common/lib/log4j-1.2.17.jarMailing list
- sourceware.orgbugzilla/show_bug.cgi?id=25620
- talosintelligence.comvulnerability_reports/TALOS-2020-1019
- lists.debian.org[debian-lts-announce] 20221017 [SECURITY] [DLA 3152-1] glibc security updateMailing list
- Siemens ProductCERTproductcert/html/ssa-398330.html
Changes to this CVE
Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).
Record modifiedcisco.com
New references:- https://lists.apache.org/thread.html/rf9fa47ab66495c78bb4120b0754dd9531ca2ff0430f6685ac9b07772%40%3Cdev.mina.apache.org%3E
- https://lists.debian.org/debian-lts-announce/2022/10/msg00021.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SPYXTDOOB4PQGTYAMZAZNJIB3FF6YQXI/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/URXOIA2LDUKHQXK4BE55BQBRI6ZZG3Y6/
and 3 more references
Show 18 original changes
Individual changes of this event as published by NVD Type Action Before After Reference added —https://lists.apache.org/thread.html/rf9fa47ab66495c78bb4120b0754dd9531ca2ff0430f6685ac9b07772%40%3Cdev.mina.apache.org%3EReference added —https://lists.debian.org/debian-lts-announce/2022/10/msg00021.htmlReference added —https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SPYXTDOOB4PQGTYAMZAZNJIB3FF6YQXI/Reference added —https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/URXOIA2LDUKHQXK4BE55BQBRI6ZZG3Y6/Reference added —https://security.gentoo.org/glsa/202101-20Reference added —https://sourceware.org/bugzilla/show_bug.cgi?id=25620Reference added —https://www.talosintelligence.com/vulnerability_reports/TALOS-2020-1019Reference removed https://lists.apache.org/thread.html/rf9fa47ab66495c78bb4120b0754dd9531ca2ff0430f6685ac9b07772%40%3Cdev.mina.apache.org%3E—Reference removed https://lists.debian.org/debian-lts-announce/2022/10/msg00021.html—Reference removed https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SPYXTDOOB4PQGTYAMZAZNJIB3FF6YQXI/—Reference removed https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/URXOIA2LDUKHQXK4BE55BQBRI6ZZG3Y6/—Reference removed https://security.gentoo.org/glsa/202101-20—Reference removed https://sourceware.org/bugzilla/show_bug.cgi?id=25620—Reference removed https://www.talosintelligence.com/vulnerability_reports/TALOS-2020-1019—Reference type removed https://lists.debian.org/debian-lts-announce/2022/10/msg00021.html Types: Mailing List, Third Party Advisory—Reference type removed https://security.gentoo.org/glsa/202101-20 Types: Third Party Advisory—Reference type removed https://sourceware.org/bugzilla/show_bug.cgi?id=25620 Types: Issue Tracking, Third Party Advisory—Reference type removed https://www.talosintelligence.com/vulnerability_reports/TALOS-2020-1019 Types: Third Party Advisory—Source identifier: talos-cna@cisco.com
Record modifiedCVE Program
New references:- https://lists.apache.org/thread.html/rf9fa47ab66495c78bb4120b0754dd9531ca2ff0430f6685ac9b07772%40%3Cdev.mina.apache.org%3E
- https://lists.debian.org/debian-lts-announce/2022/10/msg00021.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SPYXTDOOB4PQGTYAMZAZNJIB3FF6YQXI/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/URXOIA2LDUKHQXK4BE55BQBRI6ZZG3Y6/
and 3 more references
Show 18 original changes
Individual changes of this event as published by NVD Type Action Before After Reference added —https://lists.apache.org/thread.html/rf9fa47ab66495c78bb4120b0754dd9531ca2ff0430f6685ac9b07772%40%3Cdev.mina.apache.org%3EReference added —https://lists.debian.org/debian-lts-announce/2022/10/msg00021.htmlReference added —https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SPYXTDOOB4PQGTYAMZAZNJIB3FF6YQXI/Reference added —https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/URXOIA2LDUKHQXK4BE55BQBRI6ZZG3Y6/Reference added —https://security.gentoo.org/glsa/202101-20Reference added —https://sourceware.org/bugzilla/show_bug.cgi?id=25620Reference added —https://www.talosintelligence.com/vulnerability_reports/TALOS-2020-1019Reference removed https://lists.apache.org/thread.html/rf9fa47ab66495c78bb4120b0754dd9531ca2ff0430f6685ac9b07772%40%3Cdev.mina.apache.org%3E—Reference removed https://lists.debian.org/debian-lts-announce/2022/10/msg00021.html—Reference removed https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SPYXTDOOB4PQGTYAMZAZNJIB3FF6YQXI/—Reference removed https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/URXOIA2LDUKHQXK4BE55BQBRI6ZZG3Y6/—Reference removed https://security.gentoo.org/glsa/202101-20—Reference removed https://sourceware.org/bugzilla/show_bug.cgi?id=25620—Reference removed https://www.talosintelligence.com/vulnerability_reports/TALOS-2020-1019—Reference type removed https://lists.debian.org/debian-lts-announce/2022/10/msg00021.html Types: Mailing List, Third Party Advisory—Reference type removed https://security.gentoo.org/glsa/202101-20 Types: Third Party Advisory—Reference type removed https://sourceware.org/bugzilla/show_bug.cgi?id=25620 Types: Issue Tracking, Third Party Advisory—Reference type removed https://www.talosintelligence.com/vulnerability_reports/TALOS-2020-1019 Types: Third Party Advisory—Source identifier: af854a3a-2127-422b-91ae-364da2661108
Record modifiedSiemens ADP
Show 2 original changes
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2020/6xxx/CVE-2020-6096.json">CVE-2020-6096</a>Reference added —https://cert-portal.siemens.com/productcert/html/ssa-398330.htmlSource identifier: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
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<a href="https://intel.neosec.eu/en/cve/CVE-2020-6096"><img src="https://intel.neosec.eu/badge/cve/CVE-2020-6096.svg?lang=en" alt="CVE-2020-6096 – NEOSEC Intel" height="20"></a>