Evidence used
- No CISA KEV confirmation is currently recorded.
- EPSS is 0.40% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2021
CVE-2021-0262High confidence
Junos OS: QFX10002-60C: Use after free vulnerability found during static code analysis
Juniper Networks · Junos OS
6.5MediumCVSS 3.1
Scheduled
Patch availableMedium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityMedium→Operational priority:Medium, unchanged from published severity.unchanged
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
- Confirm that the asset runs Juniper Networks Junos OS and falls inside the recorded affected range.
- Verify the installed build against the product-specific fixed version after deployment.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.
Patch available01
What, why and how
Through routine static code analysis of the Juniper Networks Junos OS software codebase, the Secure Development Life Cycle team identified a Use After Free vulnerability in PFE packet processing on the QFX10002-60C switching platform. Exploitation of this vulnerability may allow a logically adjacent attacker to trigger a Denial of Service (DoS). Continued exploitation of this vulnerability will sustain the Denial of Service (DoS) condition. This issue only affects QFX10002-60C devices. No other product or platform is vulnerable to this issue. This issue affects Juniper Networks Junos OS on QFX10002-60C: 19.1 version 19.1R3-S1 and later versions; 19.1 versions prior to 19.1R3-S3; 19.2 version 19.2R2 and later versions; 19.2 versions prior to 19.2R3-S1; 20.2 versions prior to 20.2R1-S2. This issue does not affect Juniper Networks Junos OS: versions prior to 19.1R3; 19.2 versions prior to 19.2R2; any version of 19.3; version 20.2R2 and later releases.
What
Through routine static code analysis of the Juniper Networks Junos OS software codebase, the Secure Development Life Cycle team identified a Use After Free vulnerability in PFE packet processing on the QFX10002-60C switching platform. Exploitation of this vulnerability may allow a logically adjacent attacker to trigger a Denial of Service (DoS). Continued exploitation of this vulnerability will sustain the Denial of Service (DoS) condition. This issue only affects QFX10002-60C devices. No other product or platform is vulnerable to this issue. This issue affects Juniper Networks Junos OS on QFX10002-60C: 19.1 version 19.1R3-S1 and later versions; 19.1 versions prior to 19.1R3-S3; 19.2 version 19.2R2 and later versions; 19.2 versions prior to 19.2R3-S1; 20.2 versions prior to 20.2R1-S2. This issue does not affect Juniper Networks Junos OS: versions prior to 19.1R3; 19.2 versions prior to 19.2R2; any version of 19.3; version 20.2R2 and later releases.
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 disrupt the affected service.
What
Through routine static code analysis of the Juniper Networks Junos OS software codebase, the Secure Development Life Cycle team identified a Use After Free vulnerability in PFE packet processing on the QFX10002-60C switching platform. Exploitation of this vulnerability may allow a logically adjacent attacker to trigger a Denial of Service (DoS). Continued exploitation of this vulnerability will sustain the Denial of Service (DoS) condition. This issue only affects QFX10002-60C devices. No other product or platform is vulnerable to this issue. This issue affects Juniper Networks Junos OS on QFX10002-60C: 19.1 version 19.1R3-S1 and later versions; 19.1 versions prior to 19.1R3-S3; 19.2 version 19.2R2 and later versions; 19.2 versions prior to 19.2R3-S1; 20.2 versions prior to 20.2R1-S2. This issue does not affect Juniper Networks Junos OS: versions prior to 19.1R3; 19.2 versions prior to 19.2R2; any version of 19.3; version 20.2R2 and later releases.
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 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 No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.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 None recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.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 → disrupt the affected service
- 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:N/I:N/A:HCommon 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.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
- 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.
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
- 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 22 Apr 2021 · Last source change 17 Sept 2024, 00:51 UTC · CWE-416 · Use After Free
CVE recordCVE.org · 5.1
CVSS sourceCNA
EPSS source FIRST · tracked since 2026-08-14
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2021-2881
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceCNA
NVD statusNVD modified after enrichment
Core structured fields are present and their contributing authorities are shown above.
Material change intelligence
View recent updates ↗What changed after publication
No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.
CVE published
Fixed release or patch reference recorded
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.