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Fencer Vulns
critical 9.1

CVE-2020-12740 json

tcprewrite in Tcpreplay through 4.3.2 has a heap-based buffer over-read during a get_c operation.

published 2020-05-08 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-5028

cvss
9.1
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.7%
EPSS 1.7% chance of exploitation in 30 days, percentile 77%
public exploits
0
none known

Summary

tcprewrite in Tcpreplay through 4.3.2 has a heap-based buffer over-read during a get_c operation. The issue is being triggered in the function get_ipv6_next() at common/get.c.

Patch / fix

  • tcpreplay Debian 14, Debian 13, Debian 12 4.3.3-1

debian advisories DEBIAN-CVE-2020-12740

  • tcpreplay Ubuntu Pro 18.04 LTS 4.2.6-1ubuntu0.1~esm3
  • tcpreplay Ubuntu Pro 20.04 LTS 4.3.2-1ubuntu0.1~esm1

ubuntu advisories UBUNTU-CVE-2020-12740

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

  • tcpreplay openSUSE Tumbleweed 4.6.2-1.1

opensuse advisories openSUSE-SU-2026:12337-1

  • tcpreplay Arch Linux 4.3.3-1

arch linux advisories AVG-1154

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-2020-12740 updated cvss 6.5

tcpreplay: Heap-based buffer over-read in function get_ipv6_next() at common/get.c

  • 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

1.69% chance of exploitation in the next 30 days, higher than 77% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/appneta/tcpreplay/issues/576 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
NVD 2.0 6.4 AV:N/AC:L/Au:N/C:P/I:N/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.