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Fencer Vulns
critical 10.0

CVE-2021-40391 json

An out-of-bounds write vulnerability exists in the drill format T-code tool number functionality of Gerbv 2.7.0, dev (commit b5f1eacd), and…

published 2021-11-19 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-27568

cvss
10.0
version 3.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
3.0%
EPSS 3.0% chance of exploitation in 30 days, percentile 87%
public exploits
0
none known

Summary

An out-of-bounds write vulnerability exists in the drill format T-code tool number functionality of Gerbv 2.7.0, dev (commit b5f1eacd), and the forked version of Gerbv (commit 71493260). A specially-crafted drill file can lead to code execution. An attacker can provide a malicious file to trigger this vulnerability.

Patch / fix

  • gerbv Debian 13, Debian 12 2.7.1-1

debian advisories DEBIAN-CVE-2021-40391

  • gerbv Ubuntu 20.04 LTS 2.7.0-1ubuntu0.1
  • gerbv Ubuntu Pro 14.04 LTS 2.6.0-1ubuntu0.14.04.1~esm1
  • gerbv Ubuntu Pro 16.04 LTS 2.6.0-1ubuntu0.16.04.1~esm1
  • gerbv Ubuntu Pro 18.04 LTS 2.6.1-3ubuntu0.1~esm1
  • gerbv Ubuntu Pro 22.04 LTS 2.8.2-1ubuntu0.1~esm1

ubuntu advisories UBUNTU-CVE-2021-40391

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-2021-40391 updated cvss 8.3

Gerbv: out-of-bounds write in the drill format T-code tool number functionality

  • 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

2.99% chance of exploitation in the next 30 days, higher than 87% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • talosintelligence.com https://www.talosintelligence.com/vulnerability_reports/TALOS-2021-1402 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.0 10.0 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P

Affected products

  • n/a Gerbv

Classification

Weakness
  • CWE-390 Detection of Error Condition Without Action
  • CWE-755 Improper Handling of Exceptional Conditions
  • CWE-787 Out-of-bounds Write

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.