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Fencer Intel
high 8.8

CVE-2021-39537 json

An issue was discovered in ncurses through v6.2-1.

published 5y ago modified last mo. also EUVD-2021-25894 , JLSEC-2026-451

cvss
8.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
3.2%
EPSS 3.2% chance of exploitation in 30 days, percentile 88%
public exploits
0
none known

Summary

An issue was discovered in ncurses through v6.2-1. _nc_captoinfo in captoinfo.c has a heap-based buffer overflow.

Patch / fix

  • julia Ncurses_jll 6.4.0+0
  • ncurses Debian 14, Debian 13, Debian 12 6.2+20200912-1

debian advisories DEBIAN-CVE-2021-39537

  • ncurses Ubuntu 18.04 LTS 6.1-1ubuntu1.18.04.1
  • ncurses Ubuntu 20.04 LTS 6.2-0ubuntu2.1
  • ncurses Ubuntu Pro 14.04 LTS 5.9+20140118-1ubuntu1+esm2
  • ncurses Ubuntu Pro 16.04 LTS 6.0+20160213-1ubuntu1+esm2

ubuntu advisories UBUNTU-CVE-2021-39537

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

  • ncurses SLES for SAP 12 SP5, SLES 12 SP5, SLE Software Development Kit 12 SP5 5.9-75.1
  • ncurses SLE Module for Legacy 15 SP3, SLE Module for Legacy 15 SP2, SLE Module for Development Tools 15 SP3 +5 more 6.1-5.9.1

suse advisories SUSE-SU-2021:3491-1SUSE-SU-2021:3490-1

  • ncurses openSUSE Leap 15.2 6.1-lp152.8.3.1
  • ncurses openSUSE Leap 15.3 6.1-5.9.1

opensuse advisories openSUSE-SU-2021:1417-1openSUSE-SU-2021:3490-1

  • ncurses Alpine 3.12 6.2_p20200523-r1
  • ncurses Alpine 3.24, Alpine 3.23, Alpine 3.22 +9 more 6.2_p20200530-r0

alpine advisories ALPINE-CVE-2021-39537

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • ncurses CBL-Mariner 2.0 6.2-6

azure linux advisories AZL-6740

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

  • ncurses Arch Linux 6.3-1

arch linux advisories AVG-2402

Is CVE-2021-39537 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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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-2021-39537 updated cvss 5.5

ncurses: heap-based buffer overflow in _nc_captoinfo() in captoinfo.c

  • Red Hat Enterprise Linux 6 ncurses, ncurses-base, ncurses-libs, ncurses-term Red Hat Enterprise Linux 7 ncurses, ncurses-base, ncurses-libs, ncurses-term
    affected: workaround, no fix planned “Do not compile untrusted terminfo descriptions.”
  • Red Hat Enterprise Linux 8 ncurses, ncurses-base, ncurses-libs, ncurses-term, ncurses-c++-libs, ncurses-compat-libs
    affected: workaround, no fix available “Do not compile untrusted terminfo descriptions.”
  • Red Hat Enterprise Linux 9 ncurses, ncurses-base, ncurses-libs, ncurses-term, ncurses-c++-libs
    not affected: vulnerable code not present “Do not compile untrusted terminfo descriptions.”

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

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
last mo.

Exploit prediction

3.24% chance of exploitation in the next 30 days, higher than 88% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • lists.gnu.org https://lists.gnu.org/archive/html/bug-ncurses/2020-08/msg00006.html 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
OSV 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
julia Ncurses_jll
<6.4.0+0
6.4.0+0

Classification

Weakness

References

Sources

Fencer Intel 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.