How severe is CVE-2026-29085?

CVE-2026-29085 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2026-29085 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-29085?

CVE-2026-29085 affects Hono. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-29085?

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

Does CVE-2026-29085 have an EU (EUVD) identifier?

Yes. CVE-2026-29085 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-9507.

When was CVE-2026-29085 published?

CVE-2026-29085 was published on 2026-03-04 and last updated on 2026-06-17.

CVE-2026-29085

CVE-2026-29085 is a medium-severity vulnerability in Hono with a CVSS 3.x base score of 6.5. 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-74.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
EPSS exploit prediction: 0% (15th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-9507
Weakness: CWE-74
Affected product: Hono
Published: 2026-03-04
Last modified: 2026-06-17

Description

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to version 4.12.4, when using streamSSE() in Streaming Helper, the event, id, and retry fields were not validated for carriage return (\r) or newline (\n) characters. Because the SSE protocol uses line breaks as field delimiters, this could allow injection of additional SSE fields within the same event frame if untrusted input was passed into these fields. This issue has been patched in version 4.12.4.

Frequently asked questions

What is CVE-2026-29085?: Hono is a Web application framework that provides support for any JavaScript runtime. Prior to version 4.12.4, when using streamSSE() in Streaming Helper, the event, id, and retry fields were not validated for carriage return (\r) or newline (\n) characters. Because the SSE protocol uses line breaks as field delimiters, this could allow injection of additional SSE fields within the same event frame if untrusted input was passed into these fields. This issue has been patched in version 4.12.4.
How severe is CVE-2026-29085?: CVE-2026-29085 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2026-29085 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-29085?: CVE-2026-29085 affects Hono. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-29085?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-29085 have an EU (EUVD) identifier?: Yes. CVE-2026-29085 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-9507.
When was CVE-2026-29085 published?: CVE-2026-29085 was published on 2026-03-04 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:hono:hono:*:*:*:*:*:node.js:*:*

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