wren: Out-of-bounds Read
CVE-2026-2858 is a high-severity out-of-bounds read vulnerability in wren from Wren-lang, with a CVSS 3.1 base score of 7.1 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. Affected wren versions: 0.1; 0.2; 0.3, and others listed below. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.14% 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
- Check which version of wren you run against the affected versions below, and install the vendor's latest release.
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
- 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
- NoneNothing can be modified.
- 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:N/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 1.9 | Low | CNA (vuldb.com) |
| CVSS 3.1 | 3.3 | Low | CNA (vuldb.com) |
| CVSS 3.1 | 7.1 | High | NVD |
| CVSS 2.0 | 1.7 | Low | CNA (vuldb.com) |
Official description
A vulnerability was identified in wren-lang wren up to 0.4.0. This affects the function peekChar of the file src/vm/wren_compiler.c of the component Source File Parser. Such manipulation leads to out-of-bounds read. The attack needs to be performed locally. The exploit is publicly available and might be used. The project was informed of the problem early through an issue report but has not responded yet.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Out-of-bounds Read
The product reads data past the end, or before the beginning, of the intended buffer.
How developers prevent this class of flaw
- Use a language that provides appropriate memory abstractions.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Third-party and government advisories
- vuldb.com/?id.347097Third Party Advisory, VDB Entry
- vuldb.com/?submit.754489Third Party Advisory, VDB Entry
Other references
- github.com/oneafter/0122/blob/main/i1217/reproIssue Tracking, Product
- github.com/wren-lang/wren/Product
- github.com/wren-lang/wren/issues/1217Issue Tracking
- vuldb.com/?ctiid.347097Permissions Required, VDB Entry
Other vulnerabilities in wren
- 7.1 High severity
Recent Out-of-bounds Read vulnerabilities
- 7.1 High severity
- 7.8 High severity
- 7.1 High severity
- 7.1 High severity
- 7.0 High severity
- 7.1 High severity
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