CVE-2021-33477

Name: CVE-2021-33477
Creator: NVD / NIST
Published: 2021-05-20T20:15:07.397+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 8.8/10EPSS 4.01%

Last modified Jun 17, 2026

CVE-2021-33477 is a high-severity vulnerability rated 8.8/10 on the CVSS scale. rxvt-unicode 9.22, rxvt 2.7.10, mrxvt 0.5.4, and Eterm 0.9.7 allow (potentially remote) code execution because of improper handling of certain escape sequences (ESC G Q). A response is terminated by a newline.. EPSS estimates a 4.01% chance of exploitation in the next 30 days.

Description

rxvt-unicode 9.22, rxvt 2.7.10, mrxvt 0.5.4, and Eterm 0.9.7 allow (potentially remote) code execution because of improper handling of certain escape sequences (ESC G Q). A response is terminated by a newline.

Metrics

CVSS 3.1

8.8/10

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

EPSS Probability

4.01%

89.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-755

Affected Software

Vendor	Product	Versions
Eterm Project	Eterm	0.9.7
Mrxvt Project	Mrxvt	0.5.4
Rxvt-Unicode Project	Rxvt-Unicode	9.22
Rxvt Project	Rxvt	2.7.10
Fedoraproject	Fedora	33
Fedoraproject	Fedora	34
Debian	Debian Linux	9.0

References

http://cvs.schmorp.de/rxvt-unicode/Changes?view=logThird Party Advisory
http://cvs.schmorp.de/rxvt-unicode/src/command.C?r1=1.582&r2=1.583Patch, Third Party Advisory
https://git.enlightenment.org/apps/eterm.git/log/Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/05/msg00026.htmlMailing List, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/06/msg00010.htmlMailing List, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/06/msg00011.htmlMailing List, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/06/msg00012.htmlMailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/6RFMU5YXXNYYVA7G2DAHRXXHO6JKVFUT/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/AO52OLNOOKOCZSJCN3R7Q25XA32BWNWP/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/DUV4LDVZVW7KCGPAMFZD4ZJ4FVLPOX4C/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NZWGE2RJONBEHSPCBUAW72NTRTIFKZAX/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SLPVEPBH37EBR4R54RMC6GD33J37HJXD/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UXAKO6N6NKTR6Z6KVAPEXSZQMRU52SGA/
https://packetstormsecurity.com/files/162621/rxvt-2.7.0-rxvt-unicode-9.22-Code-Execution.htmlExploit, Third Party Advisory, VDB Entry
https://security.gentoo.org/glsa/202105-17Third Party Advisory
https://security.gentoo.org/glsa/202209-07Third Party Advisory
https://sourceforge.net/projects/materm/files/mrxvt%20source/Product, Third Party Advisory
https://sourceforge.net/projects/rxvt/files/rxvt-dev/Product, Third Party Advisory
https://www.openwall.com/lists/oss-security/2017/05/01/20Mailing List, Third Party Advisory
https://www.openwall.com/lists/oss-security/2021/05/17/1Exploit, Mailing List, Third Party Advisory
http://cvs.schmorp.de/rxvt-unicode/Changes?view=logThird Party Advisory
http://cvs.schmorp.de/rxvt-unicode/src/command.C?r1=1.582&r2=1.583Patch, Third Party Advisory
https://git.enlightenment.org/apps/eterm.git/log/Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/05/msg00026.htmlMailing List, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/06/msg00010.htmlMailing List, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/06/msg00011.htmlMailing List, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/06/msg00012.htmlMailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/6RFMU5YXXNYYVA7G2DAHRXXHO6JKVFUT/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/AO52OLNOOKOCZSJCN3R7Q25XA32BWNWP/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/DUV4LDVZVW7KCGPAMFZD4ZJ4FVLPOX4C/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NZWGE2RJONBEHSPCBUAW72NTRTIFKZAX/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SLPVEPBH37EBR4R54RMC6GD33J37HJXD/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UXAKO6N6NKTR6Z6KVAPEXSZQMRU52SGA/
https://packetstormsecurity.com/files/162621/rxvt-2.7.0-rxvt-unicode-9.22-Code-Execution.htmlExploit, Third Party Advisory, VDB Entry
https://security.gentoo.org/glsa/202105-17Third Party Advisory
https://security.gentoo.org/glsa/202209-07Third Party Advisory
https://sourceforge.net/projects/materm/files/mrxvt%20source/Product, Third Party Advisory
https://sourceforge.net/projects/rxvt/files/rxvt-dev/Product, Third Party Advisory
https://www.openwall.com/lists/oss-security/2017/05/01/20Mailing List, Third Party Advisory
https://www.openwall.com/lists/oss-security/2021/05/17/1Exploit, Mailing List, Third Party Advisory

Timeline

Published: May 20, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-33477?

How severe is CVE-2021-33477?

CVE-2021-33477 has a CVSS score of 8.8/10 (HIGH severity). The EPSS model estimates a 4.01% probability of exploitation in the next 30 days.

How do I fix CVE-2021-33477?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-33477?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST