# CVE-2026-128991: xschem 2.9.9 through 3.4.7 Out-of-Bounds Read via read_xschem_file() Embedded-Symbol Record

Status: published. Published: 2026-11-13. Updated: 2026-11-13.

xschem 2.9.9 through 3.4.7 contains an out-of-bounds read vulnerability in read_xschem_file() in src/save.c that mishandles embedded-symbol records lacking a preceding instance. Attackers can supply a crafted schematic beginning with a "[" record, causing xschem to read and dereference memory below the instance array and crash.

## Remediation

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: VulnCheck) — https://github.com/StefanSchippers/xschem/commit/e29af39c6133c36bdaf66603fd663231e75517f1

## Affected products and versions

- Stefan Schippers / xschem (stefanschippers/xschem): ≥ 2.9.9; ≤ 3.4.7 (affected, custom). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 5.8 (medium); CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:P/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N; source: CNA: VulnCheck

- CVSS 3.1: 5.3 (medium); CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:H; source: CNA: VulnCheck

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-125

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/StefanSchippers/xschem/commit/e29af39c6133c36bdaf66603fd663231e75517f1 (CNA: VulnCheck; patch)

- https://github.com/StefanSchippers/xschem/blob/3.4.7/src/save.c#L3138-L3141 (CNA: VulnCheck; technical-description)

- https://github.com/StefanSchippers/xschem (CNA: VulnCheck; product)

- https://www.vulncheck.com/advisories/xschem-2.9.9-through-3.4.7-out-of-bounds-read-via-read-xschem-file-embedded-symbol-record (CNA: VulnCheck; third-party-advisory)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-128991; retrieved 2026-11-13; source updated 2026-11-13

Revision: 9206269bb34d8cdd2355339a8befdecd20f65056978d04dc9bb86c1d9956fc0b

Canonical: https://y2.dev/cve/CVE-2026-128991

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