synchrony: Improperly Controlled Modification of Object Prototype Attributes
CVE-2023-45811 is a high-severity improperly controlled modification of object prototype attributes vulnerability in synchrony from Relative, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists version 2.4.4 as the first without the flaw, so updating synchrony to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.43% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update synchrony to 2.4.4 or a later version.
- Read the advisory on github.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Relative | synchrony | >= 2.0.1, < 2.4.4; 2.0.1 up to, but not including, 2.4.4 | 2.4.4 |
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
- LocalThe attacker needs local access or must trick a user into running something.
- 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
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 8.1 | High | CNA (github.com) |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
Synchrony deobfuscator is a javascript cleaner & deobfuscator. A `__proto__` pollution vulnerability exists in versions before v2.4.4. Successful exploitation could lead to arbitrary code execution. A `__proto__` pollution vulnerability exists in the `LiteralMap` transformer allowing crafted input to modify properties in the Object prototype. A fix has been released in `[email protected]`. Users are advised to upgrade. Users unable to upgrade should launch node with the [--disable-proto=delete][disable-proto] or [--disable-proto=throw][disable-proto] flags
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improperly Controlled Modification of Object Prototype Attributes
The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.
How developers prevent this class of flaw
- By freezing the object prototype first (for example, Object.freeze(Object.prototype)), modification of the prototype becomes impossible.
- By blocking modifications of attributes that resolve to object prototype, such as proto or prototype, this weakness can be mitigated.
- When handling untrusted objects, validating using a schema can be used.
More Improperly Controlled Modification of Object Prototype Attributes vulnerabilities (CWE-1321)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Recent Improperly Controlled Modification of Object Prototype Attributes vulnerabilities
- 7.5 High severity
- 9.8 Critical severity
- 9.8 Critical severity
- 9.8 Critical severity
- 7.5 High severity
- 7.8 High severity
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