VulnerabilityPublished 7 Aug 2026Updated 10 Aug 2026

CVE-2026-71850: honojs hono · Exposure of Data Element to Wrong Session

Affects honojs honoSource CVE Database V5

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Not known to be exploited · CVSS 4.8 Medium : upgrade to 4.12.34 when convenient.

Data as of 5 Nov 2026, 00:01 UTC

CVSS 3.1 base score

4.8Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.2% chance of exploitation in 30 days – higher than 18% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 4.12.34

CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:N/A:N

Attack Vector: Network
Attack Complexity: High
Privileges Required: Low
User Interaction: Required
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: High: A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected. For example, a successful attack may require an attacker to: gather knowledge about the environment in which the vulnerable target/component exists; prepare the target environment to improve exploit reliability; or inject themselves into the logical network path between the target and the resource requested by the victim in order to read and/or modify network communications (e.g., a man in the middle attack).
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 7 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 5 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade honojs hono to 4.12.34.

Affected software

Product	Affected	Fixed in
honojshono	Affected >=3.8.0 <4.12.34	Fixed in 4.12.34
npmhono`pkg:npm/hono`Other threats	Affected >=3.8.0 <4.12.34	Fixed in 4.12.34

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade hono to version 4.12.34 or later, where this issue is fixed. Until upgrading, avoid using memo() in server-side rendering contexts where request-scoped data is accessed, or ensure that memoized components do not rely on request-scoped values.

Description

Hono is a Web application framework that provides support for any JavaScript runtime. From 3.8.0 to 4.12.33, memo() from hono/jsx retains the result of a server side render and reuses it for later renders with comparator equal props, and request scoped values read inside the component take no part in that comparison, so a response can contain HTML rendered for another user's request. Components wrapped with memo() are compared by props alone; values read implicitly during rendering, such as JSX Context through createContext() and useContext(), useRequestContext() from hono/jsx-renderer, and getContext() from hono/context-storage, do not participate, and the retained result lives as long as the wrapped component, so it outlives the request that produced it. A user may receive a response containing HTML rendered for another user when both render the same memoized component with comparator equal props on the same warm instance, which may disclose another user's account or profile data, disclose request scoped secrets embedded in HTML such as CSRF tokens, or expose role specific content to users who should not receive it. This issue is fixed in version 4.12.34.

Impact

An attacker or user may receive HTML content rendered for another user's session, leading to exposure of sensitive data including account or profile information, request-scoped secrets embedded in HTML (e.g., CSRF tokens), and role-specific content that should not be accessible. This compromises confidentiality but does not affect integrity or availability.

Summary

Hono versions >=3.8.0 and <4.12.34 contain a vulnerability where the memo() function from hono/jsx caches server-side rendered HTML based solely on component props, ignoring request-scoped values like JSX Context and request context hooks. As a result, cached HTML from one user's request can be reused for another user with identical props, potentially exposing sensitive data such as user account information, request-scoped secrets like CSRF tokens, or role-specific content. The cached result lives as long as the memoized component, outliving the original request. This vulnerability is tracked as CVE-2026-71850 and is fixed in version 4.12.34.

CWE-488Exposure of Data Element to Wrong Session (opens in a new tab)
Base weakness
The product does not sufficiently enforce boundaries between the states of different sessions, causing data to be provided to, or used by, the wrong session.
Architecture and Design
Protect the application's sessions from information leakage. Make sure that a session's data is not used or visible by other sessions.
Testing
Use a static analysis tool to scan the code for information leakage vulnerabilities (e.g. Singleton Member Field).
Architecture and Design
In a multithreading environment, storing user data in Servlet member fields introduces a data access race condition. Do not use member fields to store information in the Servlet.
Attack patterns
Session Credential Falsification through Prediction (opens in a new tab)
Reusing Session IDs (aka Session Replay) (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

github.com/honojs/hono/security/advisories/GHSA-f23p-vx2j-j53r (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 15 Aug 2026, 15:34 UTC

WeaknessesCWE-488

Technical details

References

Community reviews

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