BlackTreeIndependent security intelligence
← Back to the CVE catalogue
Full vulnerability report · 2024
CVE-2021-47355High confidence

atm: nicstar: Fix possible use-after-free in nicstar_cleanup()

Linux · Linux

7.8HighCVSS 3.1
Recommended action
Within 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
Distribution package intelligence

Ubuntu vendor package status

Canonical’s release and source-package findings are shown separately from local repository availability.

1 package state
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.

Ubuntu releaseSource packageVendor stateFixed versionEvidence
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 record ↗Source updated 10 Sept 2026
Optional official sources

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

Select the national-authority views to include. The exact source language is shown on each matched advisory. Your choice is remembered on this device and encoded in the shareable URL.

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-2021-34360

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

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
01

What, why and how

In the Linux kernel, the following vulnerability has been resolved: atm: nicstar: Fix possible use-after-free in nicstar_cleanup() This module's remove path calls del_timer(). However, that function does not wait until the timer handler finishes. This means that the timer handler may still be running after the driver's remove function has finished, which would result in a use-after-free. Fix by calling del_timer_sync(), which makes sure the timer handler has finished, and unable to re-schedule itself.

What

In the Linux kernel, the following vulnerability has been resolved: atm: nicstar: Fix possible use-after-free in nicstar_cleanup() This module's remove path calls del_timer(). However, that function does not wait until the timer handler finishes. This means that the timer handler may still be running after the driver's remove function has finished, which would result in a use-after-free. Fix by calling del_timer_sync(), which makes sure the timer handler has finished, and unable to re-schedule itself.

Why

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

How

An attacker operating through local access may attempt exploitation with low privileges. 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: atm: nicstar: Fix possible use-after-free in nicstar_cleanup() This module's remove path calls del_timer(). However, that function does not wait until the timer handler finishes. This means that the timer handler may still be running after the driver's remove function has finished, which would result in a use-after-free. Fix by calling del_timer_sync(), which makes sure the timer handler has finished, and unable to re-schedule itself.

Why

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

How

An attacker operating through local access 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.
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
local access → Use After Free → cause the confidentiality, integrity or availability impact described by the vendor
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-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:L/AC:L/PR:L/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.

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.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
The issue can support a local privilege or sandbox boundary transition; normal system utilities may then be available in the gained context.
CWE-416
A

Official authority intelligence

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

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

d?id=CVE-2021-47343 Référence CVE CVE-2021-47344 https://www.cve.org/CVERecord?id=CVE-2021-47344 Référence CVE CVE-2021-47345 https://www.cve.org/CVERecord?id=CVE-2021-47345 Référence CVE CVE-2021-47347 https://www.cve.org/CVERecord?id=CVE-2021-47347 Référence CVE CVE-2021-47348 https://www.cve.org/CVERecord?id=CVE-2021-47348 Référence CVE CVE-2021-47350 https://www.cve.org/CVERecord?id=CVE-2021-47350 Référence CVE CVE-2021-47352 https://www.cve.org/CVERecord?id=CVE-2021-47352 Référence CVE CVE-2021-47353 https://www.cve.org/CVERecord?id=CVE-2021-47353 Référence CVE CVE-2021-47354 https://www.cve.org/CVERecord?id=CVE-2021-47354 Référence CVE CVE-2021-47355 https://www.cve.org/CVERecord?id=CVE-2021-47355 Référence CVE CVE-2021-47356 https://www.cve.org/CVERecord?id=CVE-2021-47356 Référence CVE CVE-2021-47357 https://www.cve.org/CVERecord?id=CVE-2021-47357 Référence CVE CVE-2021-47358 https://www.cve.org/CVERecord?id=CVE-2021-47358 Référence CVE CVE-2021-47359 https://www.cve.org/CVERecord?id=CVE-2021-47359 Référence CVE CVE-2021-47360 https://www.cve.org/CVERecord?id=CVE-2021-47360 Référence CVE CVE-2021-47361 https://www.cve.org/CVERecord?id=CVE-2021-47361 Référence CVE CVE-2021-47362 https://www.cve.org/CVERecord?id=CVE-2021-47362 Référence CVE CVE-2021-47363 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-2021-47343 Référence CVE CVE-2021-47344 https://www.cve.org/CVERecord?id=CVE-2021-47344 Référence CVE CVE-2021-47345 https://www.cve.org/CVERecord?id=CVE-2021-47345 Référence CVE CVE-2021-47347 https://www.cve.org/CVERecord?id=CVE-2021-47347 Référence CVE CVE-2021-47348 https://www.cve.org/CVERecord?id=CVE-2021-47348 Référence CVE CVE-2021-47350 https://www.cve.org/CVERecord?id=CVE-2021-47350 Référence CVE CVE-2021-47352 https://www.cve.org/CVERecord?id=CVE-2021-47352 Référence CVE CVE-2021-47353 https://www.cve.org/CVERecord?id=CVE-2021-47353 Référence CVE CVE-2021-47354 https://www.cve.org/CVERecord?id=CVE-2021-47354 Référence CVE CVE-2021-47355 https://www.cve.org/CVERecord?id=CVE-2021-47355 Référence CVE CVE-2021-47356 https://www.cve.org/CVERecord?id=CVE-2021-47356 Référence CVE CVE-2021-47357 https://www.cve.org/CVERecord?id=CVE-2021-47357 Référence CVE CVE-2021-47358 https://www.cve.org/CVERecord?id=CVE-2021-47358 Référence CVE CVE-2021-47359 https://www.cve.org/CVERecord?id=CVE-2021-47359 Référence CVE CVE-2021-47360 https://www.cve.org/CVERecord?id=CVE-2021-47360 Référence CVE CVE-2021-47361 https://www.cve.org/CVERecord?id=CVE-2021-47361 Référence CVE CVE-2021-47362 https://www.cve.org/CVERecord?id=CVE-2021-47362 Référence CVE CVE-2021-47363 https://www.cve.org/CVERecord?id=

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
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 99779c9d9ffc7775da6f7fd8a7c93ac61657bed5; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 4e2a0848ea2cab0716d46f85a8ccd5fa9a493e51; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < c471569632654e57c83512e0fc1ba0dbb4544ad6; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < a7a7b2848312cc4c3a42b6e42a8ab2e441857aba; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < bdf5334250c69fabf555b7322c75249ea7d5f148; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < a7f7c42e31157d1f0871d6a8e1a0b73a6b4ea785; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 2f958b6f6ba0854b39be748d21dfe71e0fe6580f; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 5b991df8881088448cb223e769e37cab8dd40706
Fixed
< 2.6.12; 4.4.276 ≤ 4.4.*; 4.9.276 ≤ 4.9.*; 4.14.240 ≤ 4.14.*; 4.19.198 ≤ 4.19.*; 5.4.133 ≤ 5.4.*; 5.10.51 ≤ 5.10.*; 5.12.18 ≤ 5.12.*
Action
Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
Workaround
No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
04

Evidence and provenance

Published 21 May 2024 · Last source change 11 May 2026, 13:53 UTC · CWE-416 · Use After Free

CVE recordCVE.org · 5.2
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-2021-34360
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceNIST NVD
NVD statusNVD enriched

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
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-2021-47355 · cve.blacktree.nl