CVE-2026-2858
Published: 20 February 2026
Summary
CVE-2026-2858 is a low-severity Improper Restriction of Operations within the Bounds of a Memory Buffer (CWE-119) vulnerability in Wren Wren. Its CVSS base score is 3.3 (Low).
Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked at the 4.5th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
Threat & Defense at a Glance
Threat & Defense Details
Likely Mitigating ControlsAI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Ongoing control assessments and code testing (static/dynamic analysis, fuzzing) surface memory buffer restriction failures, which are then remediated before release.
Managed runtimes used by platform-independent applications (e.g., JVM, CLR) enforce memory safety, preventing most buffer overflows that require direct memory manipulation.
Memory protections (e.g., W^X, ASLR) make exploitation of buffer-boundary violations far harder to turn into code execution.
Detects exploitation attempts that produce memory corruption, crashes, or anomalous behavior.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Out-of-bounds read in Wren parser enables local DoS via crafted input leading to application crash (T1499.004 Application or System Exploitation); no RCE, info leak, or privilege escalation impact per CVSS/description.
NVD 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…
more
is publicly available and might be used. The project was informed of the problem early through an issue report but has not responded yet.
Deeper analysisAI
CVE-2026-2858 is an out-of-bounds read vulnerability in the Wren programming language implementation, specifically affecting versions up to 0.4.0 of wren-lang/wren. The issue resides in the peekChar function within src/vm/wren_compiler.c, part of the Source File Parser component. Triggered by crafted input, it allows reading beyond allocated memory boundaries, as classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer) and CWE-125 (Out-of-bounds Read). The vulnerability carries a CVSS v3.1 base score of 3.3 (AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L), indicating low severity primarily due to its local scope and limited impact.
Exploitation requires local access on the target system with low privileges (PR:L), low attack complexity, and no user interaction. A local attacker can provide malicious input to the parser, triggering the out-of-bounds read and potentially causing a denial-of-service condition through application crash or instability, without compromising confidentiality or integrity.
No patches or official mitigations are available, as the wren-lang project was notified early via GitHub issue #1217 but has not responded. A public proof-of-concept exploit is available at https://github.com/oneafter/0122/blob/main/i1217/repro, which security practitioners should review for defensive analysis. Additional details appear in VulDB entries at https://vuldb.com/?ctiid.347097 and https://vuldb.com/?id.347097.
The exploit is publicly available and could be leveraged in targeted local attacks, though no evidence of widespread real-world exploitation has been reported.
Details
- CWE(s)