EUVD-2026-38326Published

Hono: AWS Lambda adapter merges multiple `Set-Cookie` headers into one value, dropping cookies on ALB single-header and Lattice

Collected exploitation and prediction evidence

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

cve-program · CVE-2026-54287

Published

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.25, on AWS Lambda, the ALB single-header response and the VPC Lattice v2 response join multiple Set-Cookie headers into one comma-separated value. Because commas also appear inside cookie attributes (for example Expires dates), clients cannot split the value back into individual cookies and silently drop or misparse them. This vulnerability is fixed in 4.12.25.

Source published: 22 Jun 2026 17:13:14 UTC
Source modified: 22 Jun 2026 17:36:59 UTC
Observed here: 23 Oct 2026 15:48:27 UTC
Source terms: CVE Program Terms of Use

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CVSS 3.1 · 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

euvd · EUVD-2026-38326

Published

EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON.

Original publisher date fields

datePublished: Jun 22, 2026, 5:13:14 PM

dateUpdated: Jun 22, 2026, 5:36:59 PM

Source published: Jun 22, 2026, 5:13:14 PM (timezone not stated)
Source modified: Jun 22, 2026, 5:36:59 PM (timezone not stated)
Observed here: 7 Nov 2026 12:29:07 UTC
Source terms: ENISA EUVD · source terms and attribution apply

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EUVD CVSS 3.1 · 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

nvd · CVE-2026-54287

Published

NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON.

Source analysis status: Deferred

Weakness classifications: CWE-116

Original publisher date fields

published: 2026-06-22T18:16:47.350

lastModified: 2026-10-25T23:10:00.167

Source published: 22 Jun 2026 18:16:47 UTC
Source modified: 25 Oct 2026 23:10:00 UTC
Observed here: 27 Oct 2026 14:13:32 UTC
Source terms: NIST NVD usage terms; underlying source attribution retained

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CVSS 3.1 · [email protected] · Secondary · 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

osv · GHSA-j6c9-x7qj-28xf

Published

### Summary On AWS Lambda, the ALB single-header response and the VPC Lattice v2 response join multiple `Set-Cookie` headers into one comma-separated value. Because commas also appear inside cookie attributes (for example `Expires` dates), clients cannot split the value back into individual cookies and silently drop or misparse them. ### Details Per RFC 6265, each cookie must be its own `Set-Cookie` header line, and commas may appear inside attribute values. Joining cookies with `", "` collides with those commas, producing a value that clients cannot reliably split. Only ALB single-header mode and VPC Lattice v2 are affected; API Gateway v1/v2 and ALB with multi-value headers enabled already use an array and are unaffected. ### Impact A client may receive only one of the cookies, a malformed cookie, or none. Session, CSRF, or preference cookies can silently fail to apply, breaking sessions or forcing re-authentication. This affects applications that set multiple cookies per response and run on AWS Lambda behind an ALB in single-header mode (the default) or VPC Lattice v2.

Source published: 16 Jun 2026 14:08:40 UTC
Source modified: 10 Sep 2026 03:50:49 UTC
Observed here: 24 Oct 2026 13:17:17 UTC
Source terms: GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Publisher rating · MODERATE