Hono: SSE Control Field Injection via CR/LF in writeSSE()
cve-program · CVE-2026-29085
PublishedHono 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.
Read the publisher's advisoryeuvd · EUVD-2026-9507
PublishedHono 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.
Read the publisher's advisorynvd · CVE-2026-29085
PublishedHono 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.
Read the publisher's advisoryosv · GHSA-p6xx-57qc-3wxr
Published## Summary 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. ## Details The SSE helper builds event frames by joining lines with `\n`. While multi-line `data:` fields are handled according to the SSE specification, the `event`, `id`, and `retry` fields previously allowed raw values without rejecting embedded CR/LF characters. Including CR/LF in these control fields could allow unintended additional fields (such as `data:`, `id:`, or `retry:`) to be injected into the event stream. The issue has been fixed by rejecting CR/LF characters in these fields. ## Impact An attacker could manipulate the structure of SSE event frames if an application passed user-controlled input directly into `event`, `id`, or `retry`. Depending on application behavior, this could result in injected SSE fields or altered event stream handling. Applications that render `e.data` in an unsafe manner (for example, using `innerHTML`) could potentially expose themselves to client-side script injection. This issue affects applications that rely on the SSE helper to enforce protocol-level constraints.
Read the publisher's advisoryAffected versions, risk and source history
Exploitation and risk
Source statusCISA KEV lists vulnerabilities known to be exploited. FIRST EPSS estimates the likelihood of exploitation in the next 30 days. An unavailable score does not mean zero risk.
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cve-program · CVE-2026-29085
PublishedHono: SSE Control Field Injection via CR/LF in writeSSE()
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.
- Source published
- 4 Mar 2026 22:09:45 UTC
- Source modified
- 5 Mar 2026 15:41:57 UTC
- Saved here
- 23 Oct 2026 15:48:27 UTC
- Source terms
- CVE Program Terms of Use
Original source record · Cite this exact observation · Complete original publisher JSON
Source: cve-program · CVE Program Terms of Use. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.
CVSS 3.1 · 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
euvd · EUVD-2026-9507
PublishedHono 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 newlin…
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.
Additional publisher context
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: Mar 4, 2026, 10:09:45 PM
dateUpdated: Mar 5, 2026, 3:41:57 PM
1 related source bulletins · separate from aliases
WID-SEC-W-2026-0933: IBM App Connect Enterprise (Hono und Undici): Mehrere Schwachstellen
CVE-2026-1525 · CVE-2026-1526 · CVE-2026-1528 · CVE-2026-2229 · CVE-2026-2581 · CVE-2026-29045 · CVE-2026-29085 · CVE-2026-29086 · CVE-2026-1527
- Source published
- Mar 4, 2026, 10:09:45 PM (timezone not stated)
- Source modified
- Mar 5, 2026, 3:41:57 PM (timezone not stated)
- Saved here
- 15 Nov 2026 12:01:23 UTC
- Source terms
- ENISA EUVD · source terms and attribution apply
Original source record · Cite this exact observation · Complete original publisher JSON
Source: euvd · ENISA EUVD · source terms and attribution apply. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.
EUVD CVSS 3.1 · 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
nvd · CVE-2026-29085
PublishedHono 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 newlin…
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.
Additional publisher context
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: Analyzed
Weakness classifications: CWE-74
Original publisher date fields
published: 2026-03-04T23:16:10.423
lastModified: 2026-06-17T10:29:34.467
1 source CPE criteria · context only
- cpe:2.3:a:hono:hono:*:*:*:*:*:node.js:*:*
The original JSON retains the logical configuration operators, exclusions and version bounds.
- Source published
- 4 Mar 2026 23:16:10 UTC
- Source modified
- 17 Jun 2026 10:29:34 UTC
- Saved here
- 25 Oct 2026 07:19:03 UTC
- Source terms
- NIST NVD usage terms; underlying source attribution retained
Original source record · Cite this exact observation · Complete original publisher JSON
Source: nvd · NIST NVD usage terms; underlying source attribution retained. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.
CVSS 3.1 · [email protected] · Secondary · 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
osv · GHSA-p6xx-57qc-3wxr
PublishedHono Vulnerable to SSE Control Field Injection via CR/LF in writeSSE()
## Summary 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. ## Details The SSE helper builds event frames by joining lines with `\n`. While multi-line `data:` fields are handled according to the SSE specification, the `event`, `id`, and `retry` fields previously allowed raw values without rejecting embedded CR/LF characters. Including CR/LF in these control fields could allow unintended additional fields (such as `data:`, `id:`, or `retry:`) to be injected into the event stream. The issue has been fixed by rejecting CR/LF characters in these fields. ## Impact An attacker could manipulate the structure of SSE event frames if an application passed user-controlled input directly into `event`, `id`, or `retry`. Depending on application behavior, this could result in injected SSE fields or altered event stream handling. Applications that render `e.data` in an unsafe manner (for example, using `innerHTML`) could potentially expose themselves to client-side script injection. This issue affects applications that rely on the SSE helper to enforce protocol-level constraints.
- Source published
- 4 Mar 2026 19:48:41 UTC
- Source modified
- 10 Sep 2026 03:50:40 UTC
- Saved here
- 24 Oct 2026 13:17:17 UTC
- Source terms
- GitHub Advisory Database · CC-BY-4.0
Original source record · Cite this exact observation · Complete original publisher JSON
Source: osv · GitHub Advisory Database · CC-BY-4.0. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.
CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Publisher rating · MODERATE