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Fencer Vulns
high 8.8

CVE-2020-36403 json

HTSlib through 1.10.2 allows out-of-bounds write access in vcf_parse_format (called from vcf_parse and vcf_read).

published 2021-07-01 5 y ago modified 2026-06-17 4 mo ago also EUVD-2020-23931

cvss
8.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.6%
EPSS 1.6% chance of exploitation in 30 days, percentile 75%
public exploits
0
none known

Summary

HTSlib through 1.10.2 allows out-of-bounds write access in vcf_parse_format (called from vcf_parse and vcf_read).

Patch / fix

  • htslib Debian 14, Debian 13, Debian 12 1.11-1

debian advisories DEBIAN-CVE-2020-36403

  • libhts Package Hub 15 SP3, Package Hub 15 SP2, openSUSE Leap 15.3 +1 more 1.10.2-bp153.2.5.1

opensuse advisories openSUSE-SU-2021:1177-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2020-36403 updated cvss 8.8

htslib: out-of-bounds write access in vcf_parse_format()

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

1.59% chance of exploitation in the next 30 days, higher than 75% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/samtools/htslib/pull/1447 referenced PoC, tagged "exploit" by a source, unverified
  • bugs.chromium.org https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=24097 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
NVD 2.0 6.8 AV:N/AC:M/Au:N/C:P/I:P/A:P

Classification

Weakness

References

Sources

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.