CVE-2026-54287
Hono: AWS Lambda adapter merges multiple `Set-Cookie` headers into one value, dropping cookies on ALB single-header and Lattice
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- Low
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Hono: AWS Lambda adapter merges multiple `Set-Cookie` headers into one value, dropping cookies on ALB single-header and Lattice
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.
- Record
CVE-2026-54287- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N - Weakness
- CWE-116
- Updated
- 2026-11-02
EUVDEUVD-2026-38326
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.
- Record
EUVD-2026-38326- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-j6c9-x7qj-28xf
hono: AWS Lambda adapter merges multiple `Set-Cookie` headers into one value, dropping cookies on ALB single-header and Lattice
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.
- Record
GHSA-j6c9-x7qj-28xf- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N - Weakness
- CWE-116
- Updated
- 2026-11-02
NVD
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.
- Record
CVE-2026-54287- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N - Weakness
- CWE-116
- Updated
- 2026-11-02
OSV
Hono: AWS Lambda adapter merges multiple `Set-Cookie` headers into one value, dropping cookies on ALB single-header and Lattice
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.
- Record
CVE-2026-54287- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N - Weakness
- CWE-116
- Updated
- 2026-11-02
OSVGHSA-j6c9-x7qj-28xf
hono: AWS Lambda adapter merges multiple `Set-Cookie` headers into one value, dropping cookies on ALB single-header and Lattice
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.
- Record
GHSA-j6c9-x7qj-28xf- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N - Weakness
- CWE-116
- Updated
- 2026-11-02
OSVCLSA-2026-1790597695 No score
TuxCare security update for hono (12 CVEs)
TuxCare rebuilt hono to address 12 CVEs. Fixed in 3.12.12-tuxcare.2.
- Record
CLSA-2026-1790597695- Updated
- 2026-11-02
OSVROOT-APP-NPM-CVE-2026-54287 No score
CVE-2026-54287 in hono - Patched by Root
Root has patched CVE-2026-54287 in the hono package for Root:npm. Multiple fixed versions available.
- Record
ROOT-APP-NPM-CVE-2026-54287- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
hononpm |
before 4.12.25 | 4.12.25 |
honoTuxCare:npm From an advisory covering 11 CVEs |
3.12.12-tuxcare.0 up to 3.12.12-tuxcare.2, plus listed versions 3.12.123.12.12-tuxcare.1 |
3.12.12-tuxcare.2 |
honoRoot:npm |
before 4.12.14-aikido.7 | 4.12.14-aikido.74.12.14-aikido.84.12.12-aikido.24.12.25-aikido.1 |
@rootio/honoRoot:npm |
before 4.12.14-root.io.7 | 4.12.14-root.io.74.12.14-root.io.84.12.12-root.io.24.12.25-root.io.1 |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, facts | ||
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-54287 is a medium vulnerability (CVSS 5.3) in Honojs Hono, published June 16, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.31%, the 24th percentile. Fixed in hono 4.12.25.