What is CVE-2018-20374?

CVE-2018-20374 is a medium-severity vulnerability in Tinycc, classified under Out-of-bounds Write. CVSS score: 5.5/10. Published 2018-12-23.

How severe is CVE-2018-20374?

Medium severity. CVSS v3 base score is 5.5 out of 10.

Buffer overflow in Tinycc

CVE-2018-20374

An issue was discovered in Tiny C Compiler (aka TinyCC or TCC) 0.9.27. Compiling a crafted source file leads to an 8 byte out of bounds write in the use_section1 function in tccasm.c.

Vulnerability class: Buffer Overflow

Published 2018-12-23 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.007 (53.1th percentile), scored 2026-10-02.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 53rd percentile — 53.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.007 · newest: 0.007 · change: 0.000

Affected products

Tinycc — versions 0.9.27

Weakness classification (CWE)

CWE-787 — Out-of-bounds Write

References

lists.nongnu.org/archive/html/tinycc-devel/2018-12/msg00015.html (Exploit, Mailing List, Third Party Advisory)

Frequently asked questions

What is CVE-2018-20374?: CVE-2018-20374 is a medium-severity vulnerability in Tinycc, classified under Out-of-bounds Write. CVSS score: 5.5/10. Published 2018-12-23.
How severe is CVE-2018-20374?: Medium severity. CVSS v3 base score is 5.5 out of 10.