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Full vulnerability report · 2021
CVE-2021-33910High confidence

n/a — Allocation of Resources Without Limits or Throttling

Unknown · Unknown

Official source article: Siemens SSA-398330 ↗. Check the applicable product and release in the original source.

5.5MediumCVSS 3.1
Recommended action
Patch only the product branches with a verified fix

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 6 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityMediumOperational priority:Medium, unchanged from published severity.unchanged

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • A structured source references public exploit or proof-of-concept material.
  • Exploitation requires an existing local or physical foothold with privileges.
  • EPSS is 8.79% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict local access and enforce least privilege on affected hosts.
  • 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: As exposure requiresRemediation target: Within 365 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.

Cross-source reconciliation

Remediation availability differs by product scope

Verified remediation exists for at least one product or source, but 6 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Distribution package intelligence

Release-specific package status

Debian findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.

4 package states
Repository candidate not checked

A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.

Distribution releaseSource packageVendor stateFixed versionEvidence
Debian trixietrixie · sourcesystemdVendor fix publishedDebian records a fixed source-package version for this release.247.3-6Debian Security Tracker ↗Source updated 5 Oct 2026
Debian bookwormbookworm · sourcesystemdVendor fix publishedDebian records a fixed source-package version for this release.247.3-6Debian Security Tracker ↗Source updated 5 Oct 2026
Debian forkyforky · sourcesystemdVendor fix publishedDebian records a fixed source-package version for this release.247.3-6Debian Security Tracker ↗Source updated 5 Oct 2026
Debian sidsid · sourcesystemdVendor fix publishedDebian records a fixed source-package version for this release.247.3-6Debian Security Tracker ↗Source updated 5 Oct 2026
Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

2 current
SSA-398330 · CSAF 2.0 · revision 18 · interimSiemens ProductCERTSSA-398330: Vulnerabilities in the additional GNU/Linux subsystem of the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP >= V3.1.0 and < V3.1.5
5 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0)
  • SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0)
  • SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0)
  • SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0)
  • SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0)
Summary
The use of alloca function with an uncontrolled size in function unit_name_path_escape allows a local attacker, able to mount a filesystem on a very long path, to crash systemd and the whole system by allocating a very large space in the stack.
Remediation
Update to V3.1.5 or later version
SSA-222547 · CSAF 2.0 · revision 1 · finalSiemens ProductCERTSSA-222547: Third-Party Component Vulnerabilities in SCALANCE LPE9403 before V2.0
1 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • SCALANCE LPE9403
Summary
The use of alloca function with an uncontrolled size in function unit_name_path_escape allows a local attacker, able to mount a filesystem on a very long path, to crash systemd and the whole system by allocating a very large space in the stack.
Remediation
Update to V2.0 or later version
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-2021-20582

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 actionPatch only the product branches with a verified fix

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 6 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
01

What, why and how

basic/unit-name.c in systemd prior to 246.15, 247.8, 248.5, and 249.1 has a Memory Allocation with an Excessive Size Value (involving strdupa and alloca for a pathname controlled by a local attacker) that results in an operating system crash.

What

basic/unit-name.c in systemd prior to 246.15, 247.8, 248.5, and 249.1 has a Memory Allocation with an Excessive Size Value (involving strdupa and alloca for a pathname controlled by a local attacker) that results in an operating system crash.

Why

The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.

How

An attacker operating through local access may attempt exploitation with low privileges. If successful, the issue may disrupt the affected service.

What

basic/unit-name.c in systemd prior to 246.15, 247.8, 248.5, and 249.1 has a Memory Allocation with an Excessive Size Value (involving strdupa and alloca for a pathname controlled by a local attacker) that results in an operating system crash.

Why

The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.

How

An attacker operating through local access may attempt exploitation with low privileges. If successful, the issue may disrupt the affected service.

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
local access → Allocation of Resources Without Limits or Throttling → disrupt the affected service
Attack surface
Local
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-770 ↗

CWE-770: Allocation of Resources Without Limits or Throttling. The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.

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

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

AVLocalAttack vector: The attacker needs local access to the vulnerable system.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.CNoneConfidentiality impact: No direct loss is represented by this metric.INoneIntegrity impact: No direct loss is represented by this metric.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
The issue can support a local privilege or sandbox boundary transition; normal system utilities may then be available in the gained context.
Denial of serviceCWE-770Public 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-20210721Security Bulletin 21 Jul 2021

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 21 Jul 2021, published on 21 July 2021. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-0281Multiples vulnérabilités dans les produits Splunk

CVERecord?id=CVE-2019-17571 Référence CVE CVE-2019-20386 https://www.cve.org/CVERecord?id=CVE-2019-20386 Référence CVE CVE-2019-3842 https://www.cve.org/CVERecord?id=CVE-2019-3842 Référence CVE CVE-2019-3843 https://www.cve.org/CVERecord?id=CVE-2019-3843 Référence CVE CVE-2019-3844 https://www.cve.org/CVERecord?id=CVE-2019-3844 Référence CVE CVE-2020-13776 https://www.cve.org/CVERecord?id=CVE-2020-13776 Référence CVE CVE-2020-1712 https://www.cve.org/CVERecord?id=CVE-2020-1712 Référence CVE CVE-2020-17521 https://www.cve.org/CVERecord?id=CVE-2020-17521 Référence CVE CVE-2020-36518 https://www.cve.org/CVERecord?id=CVE-2020-36518 Référence CVE CVE-2021-33910 https://www.cve.org/CVERecord?id=CVE-2021-33910 Référence CVE CVE-2021-35937 https://www.cve.org/CVERecord?id=CVE-2021-35937 Référence CVE CVE-2021-35938 https://www.cve.org/CVERecord?id=CVE-2021-35938 Référence CVE CVE-2021-35939 https://www.cve.org/CVERecord?id=CVE-2021-35939 Référence CVE CVE-2021-46877 https://www.cve.org/CVERecord?id=CVE-2021-46877 Référence CVE CVE-2022-23302 https://www.cve.org/CVERecord?id=CVE-2022-23302 Référence CVE CVE-2022-23305 https://www.cve.org/CVERecord?id=CVE-2022-23305 Référence CVE CVE-2022-23307 https://www.cve.org/CVERecord?id=CVE-2022-23307 Référence CVE CVE-2022-31159 https://www.cve.org/CVERecord?id=

Official advisory ↗
CERT-FR · French · CERTFR-2023-AVI-1015Multiples vulnérabilités dans les produits Siemens

ecord?id=CVE-2021-28363 Référence CVE CVE-2021-28861 https://www.cve.org/CVERecord?id=CVE-2021-28861 Référence CVE CVE-2021-31239 https://www.cve.org/CVERecord?id=CVE-2021-31239 Référence CVE CVE-2021-3177 https://www.cve.org/CVERecord?id=CVE-2021-3177 Référence CVE CVE-2021-32292 https://www.cve.org/CVERecord?id=CVE-2021-32292 Référence CVE CVE-2021-3326 https://www.cve.org/CVERecord?id=CVE-2021-3326 Référence CVE CVE-2021-33294 https://www.cve.org/CVERecord?id=CVE-2021-33294 Référence CVE CVE-2021-33560 https://www.cve.org/CVERecord?id=CVE-2021-33560 Référence CVE CVE-2021-33574 https://www.cve.org/CVERecord?id=CVE-2021-33574 Référence CVE CVE-2021-33910 https://www.cve.org/CVERecord?id=CVE-2021-33910 Référence CVE CVE-2021-3426 https://www.cve.org/CVERecord?id=CVE-2021-3426 Référence CVE CVE-2021-3516 https://www.cve.org/CVERecord?id=CVE-2021-3516 Référence CVE CVE-2021-3517 https://www.cve.org/CVERecord?id=CVE-2021-3517 Référence CVE CVE-2021-3518 https://www.cve.org/CVERecord?id=CVE-2021-3518 Référence CVE CVE-2021-3520 https://www.cve.org/CVERecord?id=CVE-2021-3520 Référence CVE CVE-2021-3537 https://www.cve.org/CVERecord?id=CVE-2021-3537 Référence CVE CVE-2021-3541 https://www.cve.org/CVERecord?id=CVE-2021-3541 Référence CVE CVE-2021-3580 https://www.cve.org/CVERecord?id=CVE-2021-3580 R

Official advisory ↗
CERT-FR · French · CERTFR-2022-AVI-547Multiples vulnérabilités dans les produits Siemens

VERecord?id=CVE-2017-9946 Référence CVE CVE-2017-9947 https://www.cve.org/CVERecord?id=CVE-2017-9947 Référence CVE CVE-2020-27304 https://www.cve.org/CVERecord?id=CVE-2020-27304 Référence CVE CVE-2020-9272 https://www.cve.org/CVERecord?id=CVE-2020-9272 Référence CVE CVE-2020-9273 https://www.cve.org/CVERecord?id=CVE-2020-9273 Référence CVE CVE-2021-20317 https://www.cve.org/CVERecord?id=CVE-2021-20317 Référence CVE CVE-2021-22924 https://www.cve.org/CVERecord?id=CVE-2021-22924 Référence CVE CVE-2021-22925 https://www.cve.org/CVERecord?id=CVE-2021-22925 Référence CVE CVE-2021-33196 https://www.cve.org/CVERecord?id=CVE-2021-33196 Référence CVE CVE-2021-33910 https://www.cve.org/CVERecord?id=CVE-2021-33910 Référence CVE CVE-2021-34798 https://www.cve.org/CVERecord?id=CVE-2021-34798 Référence CVE CVE-2021-36221 https://www.cve.org/CVERecord?id=CVE-2021-36221 Référence CVE CVE-2021-37182 https://www.cve.org/CVERecord?id=CVE-2021-37182 Référence CVE CVE-2021-37209 https://www.cve.org/CVERecord?id=CVE-2021-37209 Référence CVE CVE-2021-39275 https://www.cve.org/CVERecord?id=CVE-2021-39275 Référence CVE CVE-2021-39293 https://www.cve.org/CVERecord?id=CVE-2021-39293 Référence CVE CVE-2021-4034 https://www.cve.org/CVERecord?id=CVE-2021-4034 Référence CVE CVE-2021-40438 https://www.cve.org/CVERecord?id=CV

Official advisory ↗
CERT-FR · French · CERTFR-2022-AVI-439Multiples vulnérabilités dans Axis OS

De multiples vulnérabilités ont été découvertes dans Axis OS. Elles permettent à un attaquant de provoquer un problème de sécurité non spécifié par l'éditeur.

Official advisory ↗
CERT-FR · French · CERTFR-2021-AVI-791Multiples vulnérabilités dans les produits IBM

ecord?id=CVE-2021-27218 Référence CVE CVE-2021-27219 https://www.cve.org/CVERecord?id=CVE-2021-27219 Référence CVE CVE-2021-27290 https://www.cve.org/CVERecord?id=CVE-2021-27290 Référence CVE CVE-2021-29679 https://www.cve.org/CVERecord?id=CVE-2021-29679 Référence CVE CVE-2021-29745 https://www.cve.org/CVERecord?id=CVE-2021-29745 Référence CVE CVE-2021-29894 https://www.cve.org/CVERecord?id=CVE-2021-29894 Référence CVE CVE-2021-30661 https://www.cve.org/CVERecord?id=CVE-2021-30661 Référence CVE CVE-2021-3177 https://www.cve.org/CVERecord?id=CVE-2021-3177 Référence CVE CVE-2021-3326 https://www.cve.org/CVERecord?id=CVE-2021-3326 Référence CVE CVE-2021-33910 https://www.cve.org/CVERecord?id=CVE-2021-33910 Référence CVE CVE-2021-3421 https://www.cve.org/CVERecord?id=CVE-2021-3421 Référence CVE CVE-2021-3449 https://www.cve.org/CVERecord?id=CVE-2021-3449 Référence CVE CVE-2021-3450 https://www.cve.org/CVERecord?id=CVE-2021-3450 Référence CVE CVE-2021-3516 https://www.cve.org/CVERecord?id=CVE-2021-3516 Référence CVE CVE-2021-3517 https://www.cve.org/CVERecord?id=CVE-2021-3517 Référence CVE CVE-2021-3518 https://www.cve.org/CVERecord?id=CVE-2021-3518 Référence CVE CVE-2021-3520 https://www.cve.org/CVERecord?id=CVE-2021-3520 Référence CVE CVE-2021-3537 https://www.cve.org/CVERecord?id=CVE-2021-3537 R

Official advisory ↗
CERT-FR · French · CERTFR-2021-AVI-788Multiples vulnérabilités dans IBM Cloud Foundry Migration Runtime

De multiples vulnérabilités ont été découvertes dans IBM Cloud Foundry Migration Runtime. Certaines d'entre elles permettent à un attaquant de provoquer une exécution de code arbitraire, un déni de service à distance et un contournement de la politique de sécurité.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2021-012743systemd における制限またはスロットリング無しのリソースの割り当てに関する脆弱性

systemd には、制限またはスロットリング無しのリソースの割り当て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.
Fix availability varies by product
Affected
Fixed
Update to V3.1.5 or later version
Action
Use the product-specific evidence above. Patch only products with a verified fixed release, and keep every affected or under-investigation state without a matching fix in the remediation queue.
Workaround
No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
04

Evidence and provenance

Published 20 Jul 2021 · Last source change 9 Jun 2025, 15:44 UTC · CWE-770 · Allocation of Resources Without Limits or Throttling

CVE recordCVE.org · 5.1
CVSS sourceNIST NVD
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-2021-20582
Product sourceVendor CSAF · Siemens ProductCERT
Remediation sourceVendor CSAF · Siemens ProductCERT
CWE sourceCISA ADP
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 ↗
  1. Affected versionsThe structured affected or fixed version information changed.
    Before
    n/a · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
    After
    n/a · Fixed: Update to V3.1.5 or later version
    Siemens ProductCERT ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
Fixed release recorded from official guidance
ENISA EUVD · EUVD-2021-20582↗Siemens ProductCERT security advisory · Siemens SSA-398330↗CVE authority or vendor reference↗Patch or update reference↗Patch or update reference↗Patch or update reference↗Public exploit 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-2021-33910 · cve.blacktree.nl