How severe is CVE-2026-39410?

CVE-2026-39410 has a CVSS 3.x base score of 4.8, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2026-39410 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (20th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-39410?

CVE-2026-39410 affects Hono. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-39410?

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

Does CVE-2026-39410 have an EU (EUVD) identifier?

Yes. CVE-2026-39410 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-20499.

When was CVE-2026-39410 published?

CVE-2026-39410 was published on 2026-04-08 and last updated on 2026-06-17.

CVE-2026-39410

CVE-2026-39410 is a medium-severity vulnerability in Hono with a CVSS 3.x base score of 4.8. 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-20.

Key facts

Severity: Medium (CVSS 3.x base score 4.8)
EPSS exploit prediction: 0% (20th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-20499
Weakness: CWE-20
Affected product: Hono
Published: 2026-04-08
Last modified: 2026-06-17

Description

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.12, a discrepancy between browser cookie parsing and parse() handling allows cookie prefix protections to be bypassed. Cookie names that are treated as distinct by the browser may be normalized to the same key by parse(), allowing attacker-controlled cookies to override legitimate ones. This vulnerability is fixed in 4.12.12.

Frequently asked questions

What is CVE-2026-39410?: Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.12, a discrepancy between browser cookie parsing and parse() handling allows cookie prefix protections to be bypassed. Cookie names that are treated as distinct by the browser may be normalized to the same key by parse(), allowing attacker-controlled cookies to override legitimate ones. This vulnerability is fixed in 4.12.12.
How severe is CVE-2026-39410?: CVE-2026-39410 has a CVSS 3.x base score of 4.8, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2026-39410 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (20th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-39410?: CVE-2026-39410 affects Hono. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-39410?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-39410 have an EU (EUVD) identifier?: Yes. CVE-2026-39410 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-20499.
When was CVE-2026-39410 published?: CVE-2026-39410 was published on 2026-04-08 and last updated on 2026-06-17.

References

Affected products (1)

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

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