Evidence used
- No CISA KEV confirmation is currently recorded.
- Exploitation requires an existing local or physical foothold with privileges.
- EPSS is 0.40% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2021
CVE-2020-7463High confidence
n/a FreeBSD — Use After Free
Unknown · FreeBSD
5.5MediumCVSS 3.1
Scheduled
Fix not verifiedMedium 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:Low, lowered one band.downgradedsince 4 Aug 2024
Compensating controls
- 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 Unknown FreeBSD and falls inside the recorded affected range.
- Recheck the vendor advisory before scheduling a change because no verified fixed version is currently retained.
- 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.
Fix not verified01
What, why and how
In FreeBSD 12.1-STABLE before r364644, 11.4-STABLE before r364651, 12.1-RELEASE before p9, 11.4-RELEASE before p3, and 11.3-RELEASE before p13, improper handling in the kernel causes a use-after-free bug by sending large user messages from multiple threads on the same SCTP socket. The use-after-free situation may result in unintended kernel behaviour including a kernel panic.
What
In FreeBSD 12.1-STABLE before r364644, 11.4-STABLE before r364651, 12.1-RELEASE before p9, 11.4-RELEASE before p3, and 11.3-RELEASE before p13, improper handling in the kernel causes a use-after-free bug by sending large user messages from multiple threads on the same SCTP socket. The use-after-free situation may result in unintended kernel behaviour including a kernel panic.
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 FreeBSD 12.1-STABLE before r364644, 11.4-STABLE before r364651, 12.1-RELEASE before p9, 11.4-RELEASE before p3, and 11.3-RELEASE before p13, improper handling in the kernel causes a use-after-free bug by sending large user messages from multiple threads on the same SCTP socket. The use-after-free situation may result in unintended kernel behaviour including a kernel panic.
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 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
- 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:N/I:N/A:HCommon 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.
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 not verified
- Affected
- FreeBSD: FreeBSD 12.1-RELEASE before p9, 11.4-RELEASE before p3, 11.3-RELEASE before p13
- Fixed
- No fixed version is explicitly recorded in the structured CVE data.
- Action
- No verified patch reference is present in the current structured sources. Check the vendor advisory before making a change.
- Workaround
- No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
Official vendor articles6 stored documents
Linked articles are downloaded and versioned as source evidence. A CVE mention or approved update relationship does not, by itself, verify a fix for every product branch.
- About the security content of iOS 14.5 and iPadOS 14.5 - Apple Support →Original publisher ↗Searchable text snapshot · Captured 16 Oct 2026Apple Store Mac iPad iPhone Watch Vision AirPods Home Entertainment Accessories Support 0 + "},{"name":"compact","assetInline":" "}],"analyticsAttributes":[{"name":"data-analytics-title","value":"apple home"}]},{"id":"ad4a2a26eb4836393385e9f6c61b526b4a3cb31409c5ed8730ce7a704dd7132f","name":"store","text":"
- About the security content of Safari 14.1 - Apple Support →Original publisher ↗Searchable text snapshot · Captured 16 Oct 2026Apple Store Mac iPad iPhone Watch Vision AirPods Home Entertainment Accessories Support 0 + "},{"name":"compact","assetInline":" "}],"analyticsAttributes":[{"name":"data-analytics-title","value":"apple home"}]},{"id":"ad4a2a26eb4836393385e9f6c61b526b4a3cb31409c5ed8730ce7a704dd7132f","name":"store","text":"
- About the security content of iTunes 12.11.3 for Windows - Apple Support →Original publisher ↗Searchable text snapshot · Captured 16 Oct 2026Apple Store Mac iPad iPhone Watch Vision AirPods Home Entertainment Accessories Support 0 + "},{"name":"compact","assetInline":" "}],"analyticsAttributes":[{"name":"data-analytics-title","value":"apple home"}]},{"id":"ad4a2a26eb4836393385e9f6c61b526b4a3cb31409c5ed8730ce7a704dd7132f","name":"store","text":"
- About the security content of iCloud for Windows 12.3 - Apple Support →Original publisher ↗Searchable text snapshot · Captured 16 Oct 2026Apple Store Mac iPad iPhone Watch Vision AirPods Home Entertainment Accessories Support 0 + "},{"name":"compact","assetInline":" "}],"analyticsAttributes":[{"name":"data-analytics-title","value":"apple home"}]},{"id":"ad4a2a26eb4836393385e9f6c61b526b4a3cb31409c5ed8730ce7a704dd7132f","name":"store","text":"
- About the security content of watchOS 7.4 - Apple Support →Original publisher ↗Searchable text snapshot · Captured 16 Oct 2026Apple Store Mac iPad iPhone Watch Vision AirPods Home Entertainment Accessories Support 0 + "},{"name":"compact","assetInline":" "}],"analyticsAttributes":[{"name":"data-analytics-title","value":"apple home"}]},{"id":"ad4a2a26eb4836393385e9f6c61b526b4a3cb31409c5ed8730ce7a704dd7132f","name":"store","text":"
- About the security content of macOS Big Sur 11.3 - Apple Support →Original publisher ↗Searchable text snapshot · Captured 16 Oct 2026Apple Store Mac iPad iPhone Watch Vision AirPods Home Entertainment Accessories Support 0 + "},{"name":"compact","assetInline":" "}],"analyticsAttributes":[{"name":"data-analytics-title","value":"apple home"}]},{"id":"ad4a2a26eb4836393385e9f6c61b526b4a3cb31409c5ed8730ce7a704dd7132f","name":"store","text":"
04
Evidence and provenance
Published 26 Mar 2021 · Last source change 4 Aug 2024, 09:33 UTC · CWE-416 · Use After Free
CVE recordCVE.org · 5.1
CVSS sourceNIST NVD
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-2020-28589
Product sourceCNA
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
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.
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.