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Full vulnerability report · 2021
CVE-2021-30121High confidence

(Semi-)Authenticated local file inclusion in Kaseya VSA < v9.5.6

Unknown · Unknown

6.5MediumCVSS 3.1
Recommended action
Within 7 days

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityMediumOperational priority:High, raised one band.upgradedsince 3 Aug 2024

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • A structured source references public exploit or proof-of-concept material.
  • EPSS is 4.83% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Increase monitoring for the attack path and post-exploitation behaviour described in the report.

Verification

  1. Confirm that the asset runs Unknown Unknown and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 30 daysRemediation target: Within 180 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2021-17061

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Patch available
01

What, why and how

Semi-authenticated local file inclusion The contents of arbitrary files can be returned by the webserver Example request: `https://x.x.x.x/KLC/js/Kaseya.SB.JS/js.aspx?path=C:\Kaseya\WebPages\dl.asp` A valid sessionId is required but can be easily obtained via CVE-2021-30118

What

Semi-authenticated local file inclusion The contents of arbitrary files can be returned by the webserver Example request: `https://x.x.x.x/KLC/js/Kaseya.SB.JS/js.aspx?path=C:\Kaseya\WebPages\dl.asp` A valid sessionId is required but can be easily obtained via CVE-2021-30118

Why

The product imports, requires, or includes executable functionality (such as a library) from a source that is outside of the intended control sphere.

How

An attacker operating through a network path may attempt exploitation with low privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

Semi-authenticated local file inclusion The contents of arbitrary files can be returned by the webserver Example request: `https://x.x.x.x/KLC/js/Kaseya.SB.JS/js.aspx?path=C:\Kaseya\WebPages\dl.asp` A valid sessionId is required but can be easily obtained via CVE-2021-30118

Why

The product imports, requires, or includes executable functionality (such as a library) from a source that is outside of the intended control sphere.

How

An attacker operating through a network path may attempt exploitation with low privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
Reference recorded

A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.

Likely attack path
a network path → Inclusion of Functionality from Untrusted Control Sphere → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Network
Privileges required
Low: a basic authenticated account is required
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-829 ↗

CWE-829: Inclusion of Functionality from Untrusted Control Sphere. The product imports, requires, or includes executable functionality (such as a library) from a source that is outside of the intended control sphere.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRLowPrivileges required: The attacker needs basic user-level privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.INoneIntegrity impact: No direct loss is represented by this metric.ANoneAvailability impact: No direct loss is represented by this metric.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkCWE-829Public exploit reference
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

Cyber Security Agency of Singapore · English · CSA-SB-20210714Security Bulletin 14 Jul 2021

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 14 Jul 2021, published on 14 July 2021. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2021-AVI-514Multiples vulnérabilités dans Kaseya VSA

De multiples vulnérabilités ont été découvertes dans Kaseya VSA. Elles permettent à un attaquant de provoquer un contournement de la politique de sécurité, une atteinte à la confidentialité des données et une injection de code indirecte à distance (XSS). Par ailleurs , l'éditeur a par la même occasion, publié les vulnérabilités fixées dans les versions précédentes de son produit Kaseya VSA. Ainsi, la version 9.5.6 corrige les vulnérabilités suivantes : CVE-2021-30118, CVE-2021-30117, CVE-2021-30121 permettant entre autres une injection de code (SQLi) et la version 9.5.5 corrige la vulnérabilité suivante : CVE-2021-30201 permettant à un attaquant de réaliser une exécution de code arbitraire à distance .

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2021-009000Kaseya VSA における信頼できない制御領域からの機能の組み込みに関する脆弱性

Kaseya VSA には、信頼できない制御領域からの機能の組み込みに関する脆弱性が存在します。

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
n/a
Fixed
Upgrade to a version above 9.5.6
Action
Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 9 Jul 2021 · Last source change 3 Aug 2024, 22:24 UTC · CWE-829 · Inclusion of Functionality from Untrusted Control Sphere

CVE recordCVE.org · 5.1
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2021-17061
Product sourceUnavailable
Remediation sourceCVE/CNA references
CWE sourceNIST NVD
NVD statusNVD modified after enrichment

Missing structured fields: affected product. Missing data is not evidence of low risk; review the primary advisory.

Material change intelligence

What changed after publication

View recent updates ↗

No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.

Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2021-17061↗CVE authority or vendor reference↗Patch or update reference↗Public exploit reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2021-30121 · cve.blacktree.nl