An issue was discovered in fast_ber through v0.4.

published 2021-04-21 5 y ago modified 2026-06-17 4 mo ago also EUVD-2020-16658

cvss: 7.1; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 0.9%; EPSS 0.9% chance of exploitation in 30 days, percentile 60%
public exploits: 0; none known

An issue was discovered in fast_ber through v0.4. yy::yylex() in asn_compiler.hpp has a heap-based buffer over-read.

Exploit prediction

0.91% chance of exploitation in the next 30 days, higher than 60% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/Samuel-Tyler/fast_ber/issues/30 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
NVD	3.1	7.1	CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H
NVD	2.0	5.8	AV:N/AC:M/Au:N/C:P/I:N/A:P

Classification

Weakness

CWE-125 Out-of-bounds Read

References

github.com /Samuel-Tyler/fast_ber/issues/30
exploit, third-party-advisory
cwe.mitre.org /data/definitions/126.html
technical-description

Sources

CVE List CVE-2020-23921
NVD CVE-2020-23921

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