BlackTreeCVE Intelligence
← Back to the CVE catalogue
Full vulnerability report · 2024
CVE-2021-47520High confidence

can: pch_can: pch_can_rx_normal: fix use after free

Linux · Linux

8.8HighCVSS 3.1
Recommended action
Patch only the product branches with a verified fix

High technical severity; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 1 structured product or package state 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 severityHighOperational priority:High, unchanged from published severity.unchanged

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • EPSS is 0.34% 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.
  • Monitor vendor guidance and exploitation sources for a material change.

Verification

  1. Confirm that the asset runs Linux Linux 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.

Cross-source reconciliation

Remediation availability differs by product scope

Verified remediation exists for at least one product or source, but 1 structured product or package state remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Distribution package intelligence

Release-specific package status

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

5 package states
Package result overrides the generic status

BlackTree has verified remediation for at least one product or source, but the relevant distribution still reports no fixed package for 1 affected package state shown here. Treat those rows as affected with no fix until that distribution publishes a fixed version.

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 · sourcelinuxVendor fix publishedDebian records a fixed source-package version for this release.5.15.15-1Debian Security Tracker ↗Source updated 6 Oct 2026
Debian bookwormbookworm · sourcelinuxVendor fix publishedDebian records a fixed source-package version for this release.5.15.15-1Debian Security Tracker ↗Source updated 6 Oct 2026
Debian forkyforky · sourcelinuxVendor fix publishedDebian records a fixed source-package version for this release.5.15.15-1Debian Security Tracker ↗Source updated 6 Oct 2026
Debian sidsid · sourcelinuxVendor fix publishedDebian records a fixed source-package version for this release.5.15.15-1Debian Security Tracker ↗Source updated 6 Oct 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-raspi-realtimeAffected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.Not published in this feedCanonical Ubuntu Security ↗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.

1 current
CVE-2021-47520 · CSAF 2.0 · revision 75 · interimSUSE Product Security TeamCVE-2021-47520
15 known affected

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

  • SLES 15 SP1 CHOST Images for Amazon EC2
  • SLES 15 SP2 CHOST Images for Amazon EC2
  • SLES 15 SP3 CHOST Images for Amazon EC2
  • SLES 15 SP4 CHOST Images for Amazon EC2
  • SLES 15 SP5 CHOST Images for Amazon EC2
  • SLES 15 SP1 CHOST Images for Google
  • SLES 15 SP2 CHOST Images for Google
  • SLES 15 SP3 CHOST Images for Google
  • SLES 15 SP4 CHOST Images for Google
  • SLES 15 SP5 CHOST Images for Google
  • SLES 15 SP1 CHOST Images for Microsoft Azure
  • SLES 15 SP2 CHOST Images for Microsoft Azure
Summary
In the Linux kernel, the following vulnerability has been resolved: can: pch_can: pch_can_rx_normal: fix use after free After calling netif_receive_skb(skb), dereferencing skb is unsafe. Especially, the can_frame cf which aliases skb memory is dereferenced just after the call netif_receive_skb(skb). Reordering the lines solves the issue.
Remediation
To install this SUSE Security Update use the SUSE recommended installation methods like YaST online_update or "zypper patch".
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-2021-34524

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

High technical severity; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 1 structured product or package state remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
01

What, why and how

In the Linux kernel, the following vulnerability has been resolved: can: pch_can: pch_can_rx_normal: fix use after free After calling netif_receive_skb(skb), dereferencing skb is unsafe. Especially, the can_frame cf which aliases skb memory is dereferenced just after the call netif_receive_skb(skb). Reordering the lines solves the issue.

What

In the Linux kernel, the following vulnerability has been resolved: can: pch_can: pch_can_rx_normal: fix use after free After calling netif_receive_skb(skb), dereferencing skb is unsafe. Especially, the can_frame cf which aliases skb memory is dereferenced just after the call netif_receive_skb(skb). Reordering the lines solves the issue.

Why

The program can continue using memory after it has been released, producing unsafe and attacker-influenceable behaviour.

How

An attacker operating through an adjacent network may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

In the Linux kernel, the following vulnerability has been resolved: can: pch_can: pch_can_rx_normal: fix use after free After calling netif_receive_skb(skb), dereferencing skb is unsafe. Especially, the can_frame cf which aliases skb memory is dereferenced just after the call netif_receive_skb(skb). Reordering the lines solves the issue.

Why

The program can continue using memory after it has been released, producing unsafe and attacker-influenceable behaviour.

How

An attacker operating through an adjacent network may attempt exploitation without authentication or user interaction. 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.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
an adjacent network → Use After Free → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Adjacent
Privileges required
None: unauthenticated exploitation is possible
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-416 ↗

CWE-416: Use After Free. The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.

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

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

AVAdjacentAttack vector: The attacker must be on an adjacent or logically close network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing 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.IHighIntegrity impact: A successful attack can cause a major loss.AHighAvailability impact: A successful attack can cause a major loss.
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.
UnauthenticatedCWE-416
A

Official authority intelligence

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

BSI · German · WID-SEC-2024-1235Linux Kernel: Mehrere Schwachstellen ermöglichen Denial of Service und unspezifische Angriffe

Ein lokaler Angreifer kann mehrere Schwachstellen im Linux-Kernel ausnutzen, um einen Denial-of-Service-Zustand zu erzeugen oder unspezifische Angriffe durchzuführen.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20240529Security Bulletin 29 May 2024

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 29 May 2024, published on 29 May 2024. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2024-AVI-0717Multiples vulnérabilités dans le noyau Linux de SUSE

d?id=CVE-2021-47403 Référence CVE CVE-2021-47405 https://www.cve.org/CVERecord?id=CVE-2021-47405 Référence CVE CVE-2021-47432 https://www.cve.org/CVERecord?id=CVE-2021-47432 Référence CVE CVE-2021-47438 https://www.cve.org/CVERecord?id=CVE-2021-47438 Référence CVE CVE-2021-47441 https://www.cve.org/CVERecord?id=CVE-2021-47441 Référence CVE CVE-2021-47468 https://www.cve.org/CVERecord?id=CVE-2021-47468 Référence CVE CVE-2021-47501 https://www.cve.org/CVERecord?id=CVE-2021-47501 Référence CVE CVE-2021-47506 https://www.cve.org/CVERecord?id=CVE-2021-47506 Référence CVE CVE-2021-47516 https://www.cve.org/CVERecord?id=CVE-2021-47516 Référence CVE CVE-2021-47520 https://www.cve.org/CVERecord?id=CVE-2021-47520 Référence CVE CVE-2021-47542 https://www.cve.org/CVERecord?id=CVE-2021-47542 Référence CVE CVE-2021-47546 https://www.cve.org/CVERecord?id=CVE-2021-47546 Référence CVE CVE-2021-47547 https://www.cve.org/CVERecord?id=CVE-2021-47547 Référence CVE CVE-2021-47559 https://www.cve.org/CVERecord?id=CVE-2021-47559 Référence CVE CVE-2021-47580 https://www.cve.org/CVERecord?id=CVE-2021-47580 Référence CVE CVE-2021-47582 https://www.cve.org/CVERecord?id=CVE-2021-47582 Référence CVE CVE-2021-47588 https://www.cve.org/CVERecord?id=CVE-2021-47588 Référence CVE CVE-2021-47590 https://www.cve.org/CVERecord?id=

Official advisory ↗
CERT-FR · French · CERTFR-2024-AVI-0693Multiples vulnérabilités dans le noyau Linux de SUSE

d?id=CVE-2021-47432 Référence CVE CVE-2021-47438 https://www.cve.org/CVERecord?id=CVE-2021-47438 Référence CVE CVE-2021-47441 https://www.cve.org/CVERecord?id=CVE-2021-47441 Référence CVE CVE-2021-47468 https://www.cve.org/CVERecord?id=CVE-2021-47468 Référence CVE CVE-2021-47498 https://www.cve.org/CVERecord?id=CVE-2021-47498 Référence CVE CVE-2021-47501 https://www.cve.org/CVERecord?id=CVE-2021-47501 Référence CVE CVE-2021-47506 https://www.cve.org/CVERecord?id=CVE-2021-47506 Référence CVE CVE-2021-47515 https://www.cve.org/CVERecord?id=CVE-2021-47515 Référence CVE CVE-2021-47516 https://www.cve.org/CVERecord?id=CVE-2021-47516 Référence CVE CVE-2021-47520 https://www.cve.org/CVERecord?id=CVE-2021-47520 Référence CVE CVE-2021-47534 https://www.cve.org/CVERecord?id=CVE-2021-47534 Référence CVE CVE-2021-47538 https://www.cve.org/CVERecord?id=CVE-2021-47538 Référence CVE CVE-2021-47539 https://www.cve.org/CVERecord?id=CVE-2021-47539 Référence CVE CVE-2021-47542 https://www.cve.org/CVERecord?id=CVE-2021-47542 Référence CVE CVE-2021-47546 https://www.cve.org/CVERecord?id=CVE-2021-47546 Référence CVE CVE-2021-47547 https://www.cve.org/CVERecord?id=CVE-2021-47547 Référence CVE CVE-2021-47555 https://www.cve.org/CVERecord?id=CVE-2021-47555 Référence CVE CVE-2021-47559 https://www.cve.org/CVERecord?id=

Official advisory ↗
CERT-FR · French · CERTFR-2024-AVI-0610Multiples vulnérabilités dans le noyau Linux de SUSE

d?id=CVE-2021-47379 Référence CVE CVE-2021-47383 https://www.cve.org/CVERecord?id=CVE-2021-47383 Référence CVE CVE-2021-47407 https://www.cve.org/CVERecord?id=CVE-2021-47407 Référence CVE CVE-2021-47418 https://www.cve.org/CVERecord?id=CVE-2021-47418 Référence CVE CVE-2021-47434 https://www.cve.org/CVERecord?id=CVE-2021-47434 Référence CVE CVE-2021-47438 https://www.cve.org/CVERecord?id=CVE-2021-47438 Référence CVE CVE-2021-47445 https://www.cve.org/CVERecord?id=CVE-2021-47445 Référence CVE CVE-2021-47498 https://www.cve.org/CVERecord?id=CVE-2021-47498 Référence CVE CVE-2021-47518 https://www.cve.org/CVERecord?id=CVE-2021-47518 Référence CVE CVE-2021-47520 https://www.cve.org/CVERecord?id=CVE-2021-47520 Référence CVE CVE-2021-47544 https://www.cve.org/CVERecord?id=CVE-2021-47544 Référence CVE CVE-2021-47547 https://www.cve.org/CVERecord?id=CVE-2021-47547 Référence CVE CVE-2021-47555 https://www.cve.org/CVERecord?id=CVE-2021-47555 Référence CVE CVE-2021-47566 https://www.cve.org/CVERecord?id=CVE-2021-47566 Référence CVE CVE-2021-47571 https://www.cve.org/CVERecord?id=CVE-2021-47571 Référence CVE CVE-2021-47576 https://www.cve.org/CVERecord?id=CVE-2021-47576 Référence CVE CVE-2021-47587 https://www.cve.org/CVERecord?id=CVE-2021-47587 Référence CVE CVE-2021-47589 https://www.cve.org/CVERecord?id=

Official advisory ↗
CERT-FR · French · CERTFR-2024-AVI-0526Multiples vulnérabilités dans le noyau Linux de SUSE

d?id=CVE-2021-47508 Référence CVE CVE-2021-47509 https://www.cve.org/CVERecord?id=CVE-2021-47509 Référence CVE CVE-2021-47510 https://www.cve.org/CVERecord?id=CVE-2021-47510 Référence CVE CVE-2021-47511 https://www.cve.org/CVERecord?id=CVE-2021-47511 Référence CVE CVE-2021-47512 https://www.cve.org/CVERecord?id=CVE-2021-47512 Référence CVE CVE-2021-47513 https://www.cve.org/CVERecord?id=CVE-2021-47513 Référence CVE CVE-2021-47514 https://www.cve.org/CVERecord?id=CVE-2021-47514 Référence CVE CVE-2021-47516 https://www.cve.org/CVERecord?id=CVE-2021-47516 Référence CVE CVE-2021-47518 https://www.cve.org/CVERecord?id=CVE-2021-47518 Référence CVE CVE-2021-47520 https://www.cve.org/CVERecord?id=CVE-2021-47520 Référence CVE CVE-2021-47521 https://www.cve.org/CVERecord?id=CVE-2021-47521 Référence CVE CVE-2021-47522 https://www.cve.org/CVERecord?id=CVE-2021-47522 Référence CVE CVE-2021-47523 https://www.cve.org/CVERecord?id=CVE-2021-47523 Référence CVE CVE-2021-47524 https://www.cve.org/CVERecord?id=CVE-2021-47524 Référence CVE CVE-2021-47525 https://www.cve.org/CVERecord?id=CVE-2021-47525 Référence CVE CVE-2021-47526 https://www.cve.org/CVERecord?id=CVE-2021-47526 Référence CVE CVE-2021-47527 https://www.cve.org/CVERecord?id=CVE-2021-47527 Référence CVE CVE-2021-47528 https://www.cve.org/CVERecord?id=

Official advisory ↗
CERT-FR · French · CERTFR-2024-AVI-0496Multiples vulnérabilités dans le noyau Linux de SUSE

d?id=CVE-2021-47508 Référence CVE CVE-2021-47509 https://www.cve.org/CVERecord?id=CVE-2021-47509 Référence CVE CVE-2021-47510 https://www.cve.org/CVERecord?id=CVE-2021-47510 Référence CVE CVE-2021-47511 https://www.cve.org/CVERecord?id=CVE-2021-47511 Référence CVE CVE-2021-47512 https://www.cve.org/CVERecord?id=CVE-2021-47512 Référence CVE CVE-2021-47513 https://www.cve.org/CVERecord?id=CVE-2021-47513 Référence CVE CVE-2021-47514 https://www.cve.org/CVERecord?id=CVE-2021-47514 Référence CVE CVE-2021-47516 https://www.cve.org/CVERecord?id=CVE-2021-47516 Référence CVE CVE-2021-47518 https://www.cve.org/CVERecord?id=CVE-2021-47518 Référence CVE CVE-2021-47520 https://www.cve.org/CVERecord?id=CVE-2021-47520 Référence CVE CVE-2021-47521 https://www.cve.org/CVERecord?id=CVE-2021-47521 Référence CVE CVE-2021-47522 https://www.cve.org/CVERecord?id=CVE-2021-47522 Référence CVE CVE-2021-47523 https://www.cve.org/CVERecord?id=CVE-2021-47523 Référence CVE CVE-2021-47524 https://www.cve.org/CVERecord?id=CVE-2021-47524 Référence CVE CVE-2021-47525 https://www.cve.org/CVERecord?id=CVE-2021-47525 Référence CVE CVE-2021-47526 https://www.cve.org/CVERecord?id=CVE-2021-47526 Référence CVE CVE-2021-47527 https://www.cve.org/CVERecord?id=CVE-2021-47527 Référence CVE CVE-2021-47528 https://www.cve.org/CVERecord?id=

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2021-020942Linux の Linux Kernel における解放済みメモリの使用に関する脆弱性

Linux の Linux Kernel には、解放済みメモリの使用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
Linux: < 2.6.37, 4.4.295 ≤ 4.4.*, 4.9.293 ≤ 4.9.*, 4.14.258 ≤ 4.14.*, 4.19.221 ≤ 4.19.*, 5.4.165 ≤ 5.4.*, 5.10.85 ≤ 5.10.*, 5.15.8 ≤ 5.15.*, 5.16 ≤ *
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 24 May 2024 · Last source change 5 Aug 2026, 08:48 UTC · CWE-416 · Use After Free

CVE recordCVE.org · 5.2
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-2021-34524
Product sourceVendor CSAF · SUSE Product Security Team
Remediation sourceVendor CSAF · SUSE Product Security Team
CWE sourceNIST NVD
NVD statusNVD modified after enrichment

Core structured fields are present and their contributing authorities are shown above.

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-2021-34524↗Vendor CSAF · SUSE Product Security Team↗CVE authority or vendor reference↗Patch or update reference↗Patch or update reference↗Patch or update 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-2021-47520 · cve.blacktree.nl