Hono is a Web application framework that provides support for any JavaScript runtime. From 4.7.0 to 4.12.33, the Proxy Helper proxy() function in hono/proxy does not remove response headers named by the origin's Connection header. Per RFC 9110 Section 7.6.1, an intermediary must remove the header fields listed in a message's Connection header field before forwarding the message, in addition to the well known hop by hop headers, but the proxy() function only removed the well known hop by hop headers, including Connection itself, from origin responses. A client may therefore receive response headers that the origin intended only for its immediate peer, disclosing connection scoped or internal metadata contained in such headers, when an application proxies responses from an origin that declares additional, non standard headers as hop by hop via the Connection response header. This issue is fixed in version 4.12.34.
CVE-2026-71849
This low-severity CVE scores 3.7 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.2%, top 85% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
- Lower severity and no public exploit yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 3.7
- EG Score
- 3.7(medium)
- EG Risk
- 17(Track)EG Risk 17/100SSVC: Track
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity37% × 45%Exploitation0% × 40%Automatability0% × 15%Action: Routine — remediate on your standard cadence. - EPSS PROB
- 0%
- EPSS %ILE
- 15%
- KEV
- Not listed
Published
August 7, 2026
Last Modified
August 10, 2026
References (3)
- security-advisories@githubhttps://github.com/honojs/hono/commit/720b566290793d4358bf39843adcb7cf4da4548f
- security-advisories@githubhttps://github.com/honojs/hono/releases/tag/v4.12.34
- security-advisories@githubhttps://github.com/honojs/hono/security/advisories/GHSA-79qm-7rj5-m7r9
Vendor Advisories for CVE-2026-71849(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Affected Packages
(1 across 1 ecosystem)
npm(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| hono | — | 4.12.34 | — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 11× in last 7d / 22× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-08-20 22:56 UTCEPSS rescore
- 2026-08-19 17:04 UTCEPSS rescore
- 2026-08-19 04:32 UTCEG score recompute
- 2026-08-18 13:49 UTCEPSS rescore
- 2026-08-18 13:49 UTCEPSS rescore
- 2026-08-17 13:47 UTCEPSS rescore
- 2026-08-16 14:56 UTCEPSS rescore
- 2026-08-16 14:56 UTCEPSS rescore
- 2026-08-16 07:29 UTCEG score recompute
- 2026-08-16 02:15 UTCEPSS rescore
- 2026-08-15 01:31 UTCEPSS rescore
- 2026-08-13 22:00 UTCEPSS rescore
- 2026-08-13 10:29 UTCEG score recompute
- 2026-08-12 13:51 UTCEPSS rescore
- 2026-08-11 00:00 UTCEPSS rescore
- 2026-08-10 13:29 UTCEG score recompute
- 2026-08-10 12:24 UTCEG score recompute
- 2026-08-09 13:47 UTCEPSS rescore
- 2026-08-08 16:37 UTCEPSS rescore
- 2026-08-07 19:28 UTCEG score recompute
- 2026-08-07 18:47 UTCEG score recompute
- 2026-08-07 18:47 UTCMITRE cvelistV5first tracked
Related CVEs(same CWE)
Frequently asked(5)
What is CVE-2026-71849?
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Is CVE-2026-71849 actively exploited?
What is the CVSS score of CVE-2026-71849?
How do I remediate CVE-2026-71849?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-71849
Is Your Infrastructure Affected by CVE-2026-71849?
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