CVE-2021-33477

Exp

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.

Published: 2021-05-20 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-33477 is rated High Exploit Risk (81.7/100): CVSS High severity, with medium exploitation likelihood (EPSS 4.09%). 2 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2021-33477

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2021-33477

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-07-22 4.01% 4.09% +0.08%
2 2026-06-15 1.21% 4.01% +2.80%
3 2026-04-19 — 1.21% —

Full EPSS history (38 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-33477

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.8 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.8 5.9 [email protected]
6.5 2.0 MEDIUM
AV:N/AC:L/Au:S/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:S)
A single authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 8.0 6.4 [email protected]

Weakness enumeration for CVE-2021-33477

OS Trackers for CVE-2021-33477

vendor priority summary link
alpine high CVE-2021-33477: 2 source package rows (mrxvt, rxvt-unicode); 29 state rows across 10 repos (3.10-main, 3.11-main, 3.17-community, 3.18-community, 3.19-community, 3.20-community, 3.21-community, 3.22-community, 3.23-community, edge-community); fixed 29, open 0. https://security.alpinelinux.org/vuln/CVE-2021-33477
debian not yet assigned CVE-2021-33477 not yet assigned priority: Debian including 2 source packages (eterm, rxvt-unicode), 9 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 9. https://security-tracker.debian.org/tracker/CVE-2021-33477
gentoo normal CVE-2021-33477: 2 GLSA(s) (202105-17, 202209-07), 2 atom(s) (x11-terms/mrxvt, x11-terms/rxvt-unicode); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-33477
ubuntu medium CVE-2021-33477 medium priority: Ubuntu including 4 source packages (eterm, mrxvt, rxvt, rxvt-unicode), 64 status rows across 16 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 31, not-affected 14, ignored 8, needed 8, released 3. https://ubuntu.com/security/CVE-2021-33477

Affected software / configurations for CVE-2021-33477

Vendor Product Version Raw CPE
eterm_project eterm 0.9.7 cpe:2.3:a:eterm_project:eterm:0.9.7:*:*:*:*:*:*:*
mrxvt_project mrxvt 0.5.4 cpe:2.3:a:mrxvt_project:mrxvt:0.5.4:*:*:*:*:*:*:*
rxvt-unicode_project rxvt-unicode 9.22 cpe:2.3:a:rxvt-unicode_project:rxvt-unicode:9.22:*:*:*:*:*:*:*
rxvt_project rxvt 2.7.10 cpe:2.3:a:rxvt_project:rxvt:2.7.10:*:*:*:*:*:*:*
fedoraproject fedora 33 cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
fedoraproject fedora 34 cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
debian debian_linux 9.0 cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*

References for CVE-2021-33477

URL Tags
http://cvs.schmorp.de/rxvt-unicode/Changes?view=log Third Party Advisory
http://cvs.schmorp.de/rxvt-unicode/src/command.C?r1=1.582&r2=1.583 Patch Third Party Advisory
https://git.enlightenment.org/apps/eterm.git/log/ Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/05/msg00026.html Mailing List Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/06/msg00010.html Mailing List Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/06/msg00011.html Mailing List Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/06/msg00012.html Mailing 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.html Exploit Third Party Advisory VDB Entry
https://security.gentoo.org/glsa/202105-17 Third Party Advisory
https://security.gentoo.org/glsa/202209-07 Third 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/2017/05/01/20 Mailing List Third Party Advisory
https://www.openwall.com/lists/oss-security/2021/05/17/1 Exploit Mailing List Third Party Advisory
cvelogic Threat Intelligence