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CVE-2021-39537

29
FAUCET Score

CVE-2021-39537 is a heap-based buffer overflow vulnerability in the _nc_captoinfo function of ncurses versions through 6.2-1, affecting Apple macOS and GNU ncurses products. With a CVSS score of 8.8 (High), it can be exploited remotely with low attack complexity, potentially leading to high impact on confidentiality, integrity, and availability if a user interaction is successful. There is currently no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
<= 6.2.1CPE matchmatch criteria
cpe:2.3:a:invisible-island:ncurses:*:*:*:*:*:*:*:*
10.12.6CPE matchmatch criteria
cpe:2.3:o:apple:mac_os_x:10.12.6:*:*:*:*:*:*:*
11.7CPE matchmatch criteria
cpe:2.3:o:apple:macos:11.7:*:*:*:*:*:*:*
13.0CPE matchmatch criteria
cpe:2.3:o:apple:macos:13.0:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

8.8HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
2.8
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
3.23%
Probability of exploitation in next 30 days
EPSS Percentile
86.9%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0323 is in the 86th percentile among its peer group of 14,855 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.2 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.1 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (5)

microsoftpatch availablevia msrc
Product: 18990-16820Fixed in: 6.2-5
microsoftpatch availablevia msrc
Product: 18991-16823Fixed in: 6.2-6
microsoftpatch availablevia msrc
Product: cm1 ncurses 6.2-5 on CBL Mariner 1.0Fixed in: 6.2-5
microsoftpatch availablevia msrc
Product: cbl2 ncurses 6.2-6 on CBL Mariner 2.0Fixed in: 6.2-6
redhatvendor investigatingvia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: ncurses

Vendor Advisories (2)

microsoft2021-Sep/CVE-2021-39537Important

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

Sep 14, 2021
redhatCVE-2021-39537Low

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

Aug 4, 2020

References

cvsweb.netbsd.org / bsdweb.cgi/pkgsrc/devel/ncurses/patches/patch-ncurses_tinfo_captoinfo.c
PatchThird Party Advisory
seclists.org / fulldisclosure/2022/Oct/28
Mailing ListThird Party Advisory
seclists.org / fulldisclosure/2022/Oct/41
Mailing ListThird Party Advisory
seclists.org / fulldisclosure/2022/Oct/43
Mailing ListThird Party Advisory
seclists.org / fulldisclosure/2022/Oct/45
Mailing ListThird Party Advisory
lists.debian.org / debian-lts-announce/2023/12/msg00004.html
lists.gnu.org / archive/html/bug-ncurses/2020-08/msg00006.html
ExploitMailing ListVendor Advisory
lists.gnu.org / archive/html/bug-ncurses/2021-10/msg00023.html
Mailing ListVendor Advisory
security.netapp.com / advisory/ntap-20230427-0012
support.apple.com / kb/HT213443
Third Party Advisory
support.apple.com / kb/HT213444
Third Party Advisory
support.apple.com / kb/HT213488
Third Party Advisory