How severe is CVE-2026-28499?

CVE-2026-28499 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2026-28499 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (18th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-28499?

CVE-2026-28499 affects Vapor Leafkit. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-28499?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-28499 have an EU (EUVD) identifier?

Yes. CVE-2026-28499 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-12696.

When was CVE-2026-28499 published?

CVE-2026-28499 was published on 2026-03-18 and last updated on 2026-06-17.

CVE-2026-28499

CVE-2026-28499 is a medium-severity vulnerability in Vapor Leafkit with a CVSS 3.x base score of 6.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-79.

Key facts

Severity: Medium (CVSS 3.x base score 6.1)
CVSS v4: 6.9
EPSS exploit prediction: 0% (18th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-12696
Weakness: CWE-79
Affected product: Vapor Leafkit
Published: 2026-03-18
Last modified: 2026-06-17

Description

LeafKit is a templating language with Swift-inspired syntax. Prior to version 1.14.2, HTML escaping doesn't work correctly when a template prints a collection (Array / Dictionary) via `#(value)`. This can result in XSS, allowing potentially untrusted input to be rendered unescaped. Version 1.14.2 fixes the issue.

Frequently asked questions

What is CVE-2026-28499?: LeafKit is a templating language with Swift-inspired syntax. Prior to version 1.14.2, HTML escaping doesn't work correctly when a template prints a collection (Array / Dictionary) via `#(value)`. This can result in XSS, allowing potentially untrusted input to be rendered unescaped. Version 1.14.2 fixes the issue.
How severe is CVE-2026-28499?: CVE-2026-28499 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2026-28499 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (18th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-28499?: CVE-2026-28499 affects Vapor Leafkit. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-28499?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-28499 have an EU (EUVD) identifier?: Yes. CVE-2026-28499 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-12696.
When was CVE-2026-28499 published?: CVE-2026-28499 was published on 2026-03-18 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:vapor:leafkit:*:*:*:*:*:*:*:*

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