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Fencer Vulns
medium 5.5

CVE-2018-19974 json

In YARA 3.8.1, bytecode in a specially crafted compiled rule can read uninitialized data from VM scratch memory in libyara/exec.c.

published 2018-12-17 7 y ago modified 2026-06-17 4 mo ago also EUVD-2018-11641

cvss
5.5
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.3%
EPSS 1.3% chance of exploitation in 30 days, percentile 69%
public exploits
0
none known

Summary

In YARA 3.8.1, bytecode in a specially crafted compiled rule can read uninitialized data from VM scratch memory in libyara/exec.c. This can allow attackers to discover addresses in the real stack (not the YARA virtual stack).

Patch / fix

  • yara Debian 14, Debian 13, Debian 12 3.8.1-2

debian advisories DEBIAN-CVE-2018-19974

  • yara Ubuntu Pro 16.04 LTS 3.4.0+dfsg-2ubuntu0.1~esm1
  • yara Ubuntu Pro 18.04 LTS 3.7.1-1ubuntu2+esm1

ubuntu advisories UBUNTU-CVE-2018-19974

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

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-2018-19974 updated cvss 5.3

yara: Multiple issues

  • 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

1.26% chance of exploitation in the next 30 days, higher than 69% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • bnbdr.github.io https://bnbdr.github.io/posts/extracheese/ referenced PoC, tagged "exploit" by a source, unverified
  • github.com https://github.com/VirusTotal/yara/issues/999 referenced PoC, tagged "exploit" by a source, unverified
  • github.com https://github.com/bnbdr/swisscheese/ referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.0 5.5 CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:P/I:N/A:N

Classification

Weakness
  • CWE-908 Use of Uninitialized Resource

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.