CVE-2021-27135
CVE-2021-27135 is a critical-severity vulnerability in Invisible-island Xterm with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.
Key facts
- Severity: Critical (CVSS 3.x base score 9.8)
- CVSS v2: 7.5
- EPSS exploit prediction: 8% (94th percentile)
- Actively exploited: Not listed in CISA KEV
- Affected product: Invisible-island Xterm
- Published:
- Last modified:
Description
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.
Frequently asked questions
- What is CVE-2021-27135?
- 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.
- How severe is CVE-2021-27135?
- CVE-2021-27135 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
- Is CVE-2021-27135 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 8% (94th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2021-27135?
- CVE-2021-27135 primarily affects Invisible-island Xterm. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
- How do I fix CVE-2021-27135?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
- When was CVE-2021-27135 published?
- CVE-2021-27135 was published on 2021-02-10 and last updated on 2026-06-17.
References
- http://seclists.org/fulldisclosure/2021/May/52
- http://www.openwall.com/lists/oss-security/2021/02/10/7
- https://access.redhat.com/security/cve/CVE-2021-27135
- https://bugzilla.redhat.com/show_bug.cgi?id=1927559
- https://bugzilla.suse.com/show_bug.cgi?id=1182091
- https://github.com/ThomasDickey/xterm-snapshots/commit/82ba55b8f994ab30ff561a347b82ea340ba7075c
- https://invisible-island.net/xterm/xterm.log.html
- https://lists.debian.org/debian-lts-announce/2021/02/msg00019.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/35LK2ZXEIJUOGOA7FV2TJL3L6LFJ4X5S/
- https://news.ycombinator.com/item?id=26524650
- https://security.gentoo.org/glsa/202208-22
- https://www.openwall.com/lists/oss-security/2021/02/09/7
- https://www.openwall.com/lists/oss-security/2021/02/09/9
Affected products (3)
- cpe:2.3:a:invisible-island:xterm:*:*:*:*:*:*:*:*
- cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
- cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
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