VulnerabilityPublished 16 Sep 2026

CVE-2026-89186: ZenHive mpp · Use of Cache Containing Sensitive Information

Affects ZenHive mppSource CVE Database V5

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Not known to be exploited · CVSS 6.3 Medium : upgrade to 0.16.2 when convenient.

Data as of 31 Oct 2026, 08:20 UTC

CVSS 4.0 base score

6.3Medium

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

EPSS: 0.5% chance of exploitation in 30 days – higher than 44% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 0.16.2, 2fd91a5ecbd0b0ad2a4ac202b79659e8126dbc0b

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: Present
Privileges Required: None
User Interaction: None
Vulnerable system confidentiality: Low
Vulnerable system integrity: None
Vulnerable system availability: None
Subsequent system confidentiality: Low
Subsequent system integrity: None
Subsequent system availability: None

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

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, 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: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: Present: The successful attack depends on the presence of specific deployment and execution conditions of the vulnerable system that enable the attack. These include: a race condition must be won to successfully exploit the vulnerability (the successfulness of the attack is conditioned on execution conditions that are not under full control of the attacker, or the attack may need to be launched multiple times against a single target before being successful); the attacker must inject themselves into the logical network path between the target and the resource requested by the victim (e.g. vulnerabilities requiring an on-path attacker).
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the Vulnerable System.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system availability: None: There is no impact to availability within the Vulnerable System.
Subsequent system confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the Subsequent System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 16 Sep 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 30 Oct 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 mpp to 0.16.2; mpp to 2fd91a5ecbd0b0ad2a4ac202b79659e8126dbc0b.

Affected software

Product	Affected	Fixed in
ZenHivempp	Affected >=0.1.0 <0.16.2	Fixed in 0.16.2
ZenHivempp	Affected ≥ 2d4d1d94aae7790ae0623063961adbeef171fa71, < 2fd91a5ecbd0b0ad2a4ac202b79659e8126dbc0b	Fixed in 2fd91a5ecbd0b0ad2a4ac202b79659e8126dbc0b
Hexmpp`pkg:hex/mpp`Other threats	Affected >=0.1.0 <0.16.2	Fixed in 0.16.2

CPE configurations (1)

cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:*

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

AI-suggested

If you cannot patch yet, applications using mpp should avoid overriding the cache-control header set by the library or implement additional controls to prevent caching of paid responses in shared caches.

Description

Use of Cache Containing Sensitive Information in ZenHive mpp allows a shared HTTP cache to store a paid response and serve it to clients that never paid. MPP.Plug.verify_credential in lib/mpp/plug.ex sets payment-receipt and cache-control: private on the connection before the wrapped application runs, and registers no register_before_send/2 callback. Plug.Conn.put_resp_header/3 replaces an existing header, so a mounting application that sets its own cache-control on the paid resource (for example public, max-age=3600) silently overrides the private the library relies on, and a CDN or reverse proxy can then store the paid 200 together with its Payment-Receipt and serve both to unpaid clients. The library-level guarantee is therefore defeatable by the application it protects. For the same reason a downstream non-2xx response still carried Payment-Receipt, issuing a receipt for a response that delivered no resource. This issue affects mpp: from 0.1.0 before 0.16.2.

Impact

Unauthorized clients may receive paid content cached by shared HTTP caches, potentially leading to unauthorized access to paid resources. Payment receipts may be issued incorrectly for responses that did not deliver content, undermining the integrity of payment verification.

Summary

The vulnerability involves the use of a shared HTTP cache that stores a paid response along with its Payment-Receipt header and serves it to clients who have not paid. The mpp library's Plug.verify_credential function sets payment-receipt and cache-control: private headers before the application runs but does not register a before_send callback to enforce these headers. Since Plug.Conn.put_resp_header/3 replaces existing headers, an application can override the cache-control header to a public value, enabling CDNs or reverse proxies to cache and serve paid content to unpaid clients. Additionally, non-2xx responses may still carry a Payment-Receipt header, issuing receipts for responses that delivered no resource. This affects mpp versions >=0.1.0 and <0.16.2.

CWE-524Use of Cache Containing Sensitive Information (opens in a new tab)
Base weakness
The code uses a cache that contains sensitive information, but the cache can be read by an actor outside of the intended control sphere.
Architecture and Design
Protect information stored in cache.
Architecture and Design
Do not store unnecessarily sensitive information in the cache.
Architecture and Design
Consider using encryption in the cache.
OWASP ASVS 4.0.3
V8.1.1 (opens in a new tab)
V8.1.2 (opens in a new tab)
Attack patterns
Lifting Sensitive Data Embedded in Cache (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

CPE configurations (1)

Description

AI analysisMachine-generated, updated 16 Sep 2026, 08:46 UTC

WeaknessesCWE-524

Technical details

References

Community reviews

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