wren-lang wren Source File wren_compiler.c peekChar out-of-bounds

published 2026-02-20 8 mo ago modified 2026-06-17 4 mo ago also EUVD-2026-7782

cvss: 3.3; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.1%; EPSS 0.1% chance of exploitation in 30 days, percentile 3%
public exploits: 0; none known

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.

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: partial
Assessed: 8 mo ago (2026-02-24)

Exploit prediction

0.14% chance of exploitation in the next 30 days, higher than 3% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/oneafter/0122/blob/main/i1217/repro referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	4.0	4.8	CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P
CNA	3.1	3.3	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L/E:P/RL:X/RC:R
CNA	3.0	3.3	CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L/E:P/RL:X/RC:R
CNA	2.0	1.7	AV:L/AC:L/Au:S/C:N/I:N/A:P/E:POC/RL:ND/RC:UR
CNA	4.0	1.9	CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CNA	3.1	3.3	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
NVD	3.1	7.1	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
CNA	2.0	1.7	AV:L/AC:L/Au:S/C:N/I:N/A:P

Affected products

wren-lang wren

Classification

Weakness

CWE-125 Out-of-bounds Read
CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer

References

github.com /oneafter/0122/blob/main/i1217/repro
exploit, issue-tracking, product
vuldb.com /?id.347097
vdb-entry, technical-description, third-party-advisory
vuldb.com /?ctiid.347097
signature, permissions-required, vdb-entry
vuldb.com /?submit.754489
third-party-advisory, vdb-entry
github.com /wren-lang/wren/issues/1217
issue-tracking
github.com /wren-lang/wren/
product

Sources

CVE List CVE-2026-2858
NVD CVE-2026-2858

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary