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Fencer Intel
critical 9.8

CVE-2021-27135 json

xterm before Patch #366 allows remote attackers to execute arbitrary code or cause a denial of service (segmentation fault) via a crafted U…

published 5y ago modified 4mo ago also EUVD-2021-13902

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
7.9%
EPSS 7.9% chance of exploitation in 30 days, percentile 94%
public exploits
0
none known

Summary

xterm before Patch #366 allows remote attackers to execute arbitrary code or cause a denial of service (segmentation fault) via a crafted UTF-8 combining character sequence.

Patch / fix

  • invisible-island xterm 366
  • xterm Debian 14, Debian 13, Debian 12 366-1

debian advisories DEBIAN-CVE-2021-27135

  • xterm Ubuntu 16.04 LTS 322-1ubuntu1.2
  • xterm Ubuntu 18.04 LTS 330-1ubuntu2.2
  • xterm Ubuntu 20.04 LTS 353-1ubuntu1.20.04.2

ubuntu advisories UBUNTU-CVE-2021-27135

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

  • xterm RHEL 7 295-3.el7_9.1
  • xterm RHEL 8 331-1.el8_3.2
  • xterm-resize RHEL 8 331-1.el8_3.2
  • xterm RHEL 8.2 EUS 331-1.el8_2.1
  • xterm-resize RHEL 8.2 EUS 331-1.el8_2.1
  • xterm RHEL 8.1 EUS 331-1.el8_1.1
  • xterm-resize RHEL 8.1 EUS 331-1.el8_1.1

red hat advisories RHSA-2021:0651RHSA-2021:0650RHSA-2021:0617RHSA-2021:0611

  • xterm SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +10 more 308-5.3.1
  • xterm SLES for SAP 15 SP1, SLES for SAP 15, SLES 15-LTSS +10 more 330-4.3.1
  • xterm SLE Module for Basesystem 15 SP3, SLE Module for Basesystem 15 SP2 330-11.3.1
  • xterm SLES 11 SP4-LTSS, SLE Point of Sale 11 SP3 238-3.3.1

suse advisories SUSE-SU-2021:2014-1SUSE-SU-2021:2013-1SUSE-SU-2021:2011-1SUSE-SU-2021:14747-1

  • xterm openSUSE Tumbleweed 368-2.2
  • xterm openSUSE Leap 15.3 330-11.3.1
  • xterm openSUSE Leap 15.2 330-lp152.6.3.1

opensuse advisories openSUSE-SU-2024:11527-1openSUSE-SU-2021:2011-1openSUSE-SU-2021:0900-1

  • xterm AlmaLinux 8 331-1.el8_3.2
  • xterm-resize AlmaLinux 8 331-1.el8_3.2

almalinux advisories ALSA-2021:0611

  • xterm Rocky Linux 8 331-1.el8_3.2

rocky linux advisories RLSA-2021:0611

  • xterm Alpine 3.13 367-r0
  • xterm Alpine 3.24, Alpine 3.23, Alpine 3.22 +8 more 366-r0

alpine advisories ALPINE-CVE-2021-27135

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

  • xterm CBL-Mariner 2.0 372-1

azure linux advisories AZL-7454

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

  • xterm Arch Linux 366-1

arch linux advisories AVG-1565

Is CVE-2021-27135 in your stack? 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-2021-27135 updated cvss 9.6

xterm: crash when processing combining characters

  • Red Hat Enterprise Linux 6 xterm
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux AppStream (v. 8) xterm 331-1.el8_3.2, xterm-resize 331-1.el8_3.2
    fixed: vendor fix RHSA-2021:0611
  • Red Hat Enterprise Linux AppStream EUS (v. 8.1) xterm 331-1.el8_1.1, xterm-resize 331-1.el8_1.1
    fixed: vendor fix RHSA-2021:0650
  • Red Hat Enterprise Linux AppStream EUS (v. 8.2) xterm 331-1.el8_2.1, xterm-resize 331-1.el8_2.1
    fixed: vendor fix RHSA-2021:0651
  • Red Hat Enterprise Linux Client (v. 7) xterm 295-3.el7_9.1 Red Hat Enterprise Linux Server (v. 7) xterm 295-3.el7_9.1 Red Hat Enterprise Linux Workstation (v. 7) xterm 295-3.el7_9.1
    fixed: vendor fix RHSA-2021:0617
  • Red Hat Enterprise Linux 9 xterm, xterm-resize
    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

7.86% chance of exploitation in the next 30 days, higher than 94% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P

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.