CVSS 4.0
6.9 mediumCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:H/SC:N/SI:N/SA:NCVE-2026-63540 Heap-based Buffer Overflow
Medium (6.9). EPSS 0.1% estimated probability of exploitation activity in the next 30 days.
On this page
Heap-based buffer overflow for some Hyperscan before version v5.4.2.1 within Ring 3: User Applications may allow a denial of service. Unprivileged software adversary with an unauthenticated user combined with a low complexity attack may enable denial of service. This result may potentially occur via local access when attack requirements are not present without special internal knowledge and requires passive user interaction. The potential vulnerability may impact the confidentiality (none), integrity (low) and availability (high) of the vulnerable system, resulting in subsequent system confidentiality (none), integrity (none) and availability (none) impacts.
Severity
- EPSS
- 0.1% estimated probability of exploitation activity in the next 30 days; 3rd percentile. Scored 2026-11-13. A forecast for this CVE across the internet, not for your own systems.
- CWE
- CWE-122 Heap-based Buffer Overflow
- Published
- Modified
- Assigned by
- intel (CNA)
- NVD analysis
- Awaiting analysis
- Record from
- the NVD, synced
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Explain CVE-2026-63540 for an engineer deciding whether to act. Use https://cve.bz/api/public/cves/CVE-2026-63540?via=ask-ai-copy and https://cve.bz/cve/CVE-2026-63540?via=ask-ai-copy as the source of truth: what is affected and which versions fix it, whether it is in CISA KEV, public exploits, and its EPSS (an internet-wide 30-day estimate of exploitation activity, not a forecast for my systems). If they give no fixed versions, use the CVE record https://cveawg.mitre.org/api/cve/CVE-2026-63540 or the vendor advisory, not third-party mirrors. Tell me how to check whether I am affected and how to verify a fix. Cite the sources and say where they are uncertain.Opens a third-party assistant; its answer is its own, not cve.bz's. The prompt holds only this CVE's id and public links.
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Linux distributions
| Distribution | Release | Package | Fixed in | Advisory |
|---|---|---|---|---|
| Azure Linux | 3 | hyperscan | no fix listed | AZL-113492 |
From the distributions' data via OSV.dev: Microsoft's Azure Linux vulnerability data, MIT. Modified: reformatted and linked to CVE records. Credits.
Attack patterns (CAPEC)
- CAPEC-92 Forced Integer Overflow Likelihood: High · Severity: High
The attack patterns MITRE's CAPEC relates to this record's weaknesses, as MITRE names them. Credits.