CVE-2026-3386
Published: 01 March 2026
Summary
CVE-2026-3386 is a medium-severity Improper Restriction of Operations within the Bounds of a Memory Buffer (CWE-119) vulnerability in Wren Wren. Its CVSS base score is 4.8 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked at the 7.9th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified are NIST 800-53 SI-16 (Memory Protection) and SI-2 (Flaw Remediation).
Deeper analysis
CVE-2026-3386 is an out-of-bounds read vulnerability in the Wren programming language virtual machine, specifically affecting versions up to 0.4.0 of the wren-lang/wren project. The flaw resides in the emitOp function within the file src/vm/wren_compiler.c, which can be triggered to read data beyond allocated memory bounds. This issue is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer) and CWE-125 (Out-of-bounds Read), with a CVSS v3.1 base score of 3.3 indicating low severity.
Exploitation requires local access to the host (AV:L), low privileges (PR:L), and low attack complexity (AC:L) with no user interaction needed (UI:N). An attacker with these conditions can launch the attack locally, potentially causing a denial of service due to the low-impact availability disruption (A:L), while confidentiality and integrity remain unaffected (C:N/I:N) within the unchanged scope (S:U).
References indicate that an exploit has been publicly disclosed at https://github.com/oneafter/0122/blob/main/i1219/repro, and the project was notified early via GitHub issue #1219 at https://github.com/wren-lang/wren/issues/1219, but has not yet responded. No patches or official mitigations are mentioned in the available advisories from sources like VulDB (https://vuldb.com/?ctiid.348272 and https://vuldb.com/?id.348272). Practitioners should monitor the Wren repository at https://github.com/wren-lang/wren/ for updates and avoid using affected versions in local environments.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-9121
Vulnerability details
A flaw has been found in wren-lang wren up to 0.4.0. Affected by this vulnerability is the function emitOp of the file src/vm/wren_compiler.c. This manipulation causes out-of-bounds read. It is possible to launch the attack on the local host. The…
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exploit has been published and may be used. The project was informed of the problem early through an issue report but has not responded yet.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
OOB read in local Wren VM/compiler enables application crash/DoS via direct exploitation of memory bounds flaw (T1499.004).
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly enforces memory bounds checking and protections that block the out-of-bounds read in emitOp.
Requires timely application of patches to the vulnerable wren_compiler.c once fixes are released for versions <= 0.4.0.
Restricts execution of the affected Wren VM or compiler module, limiting exposure to the local out-of-bounds read flaw.