What is CVE-2020-27678?

CVE-2020-27678 is a critical-severity vulnerability in Illumos, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 9.8/10. Published 2020-10-26.

How severe is CVE-2020-27678?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Buffer overflow in Illumos

CVE-2020-27678

An issue was discovered in illumos before 2020-10-22, as used in OmniOS before r151030by, r151032ay, and r151034y and SmartOS before 20201022. There is a buffer overflow in parse_user_name in lib/libpam/pam_framework.c.

Vulnerability class: Buffer Overflow

Published 2020-10-26 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.014 (73.0th percentile), scored 2026-10-24.

Low probability of exploitation in the next 30 days, but still tracked. 73rd percentile — 73.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.014 · newest: 0.014 · change: 0.000

Affected products

Weakness classification (CWE)

CWE-120 — Buffer Copy without Checking Size of Input (Classic Buffer Overflow)

References

github.com/illumos/illumos-gate/commit/1d276e0b382cf066dae93640746d8b4c54d15452 (Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2020-27678?: CVE-2020-27678 is a critical-severity vulnerability in Illumos, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 9.8/10. Published 2020-10-26.
How severe is CVE-2020-27678?: Critical severity. CVSS v3 base score is 9.8 out of 10.