mesop: Improperly Controlled Modification of Dynamically-Determined Object Attributes
CVE-2025-30358 is a high-severity improperly controlled modification of dynamically-determined object attributes vulnerability in mesop from Mesop-dev, with a CVSS 3.1 base score of 8.1 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. Affected mesop versions: < 0.14.1. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.71% chance of exploitation within 30 days, higher than 54% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of mesop you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on github.com for workarounds and exact fixed builds.
Affected products and versions
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H. Scored by CNA (github.com).
Official description
Mesop is a Python-based UI framework that allows users to build web applications. A class pollution vulnerability in Mesop prior to version 0.14.1 allows attackers to overwrite global variables and class attributes in certain Mesop modules during runtime. This vulnerability could directly lead to a denial of service (DoS) attack against the server. Additionally, it could also result in other severe consequences given the application's implementation, such as identity confusion, where an attacker could impersonate an assistant or system role within conversations. This impersonation could potentially enable jailbreak attacks when interacting with large language models (LLMs). Just like the Javascript's prototype pollution, this vulnerability could leave a way for attackers to manipulate the intended data-flow or control-flow of the application at runtime and lead to severe consequences like remote code execution when gadgets are available. Users should upgrade to version 0.14.1 to obtain a fix for the issue.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improperly Controlled Modification of Dynamically-Determined Object Attributes
The product receives input from an upstream component that specifies multiple attributes, properties, or fields that are to be initialized or updated in an object, but it does not properly control which attributes can be modified.
How developers prevent this class of flaw
- If available, use features of the language or framework that allow specification of allowlists of attributes or fields that are allowed to be modified. If possible, prefer allowlists over denylists. For applications written with Ruby on Rails, use the attr_accessible (allowlist) or attr_protected (denylist) macros in each class that may be used in mass assignment.
- If available, use the signing/sealing features of the programming language to assure that deserialized data has not been tainted. For example, a hash-based message authentication code (HMAC) could be used to ensure that data has not been modified.
- For any externally-influenced input, check the input against an allowlist of internal object attributes or fields that are allowed to be modified.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Other vulnerabilities in mesop
- 8.7 High severity
- 7.5 High severity
- 9.8 Critical severity
- 9.8 Critical severity
Recent Improperly Controlled Modification of Dynamically-Determined Object Attributes vulnerabilities
- 9.4 Critical severity
- 9.3 Critical severity
- 9.1 Critical severity
- 7.2 High severity
- 8.8 High severity
- 7.5 High severity
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