CVE-2021-31535

highpriority · track · 43EPSS 0.106 · 96 %ileDEEURUUS

grimoire priorityP1 · Urgent

Exploitable?

—

no known exploitation

Likely / severe?

10.6% (96th) EPSS

CVSS 7.5 · high

Is it mine?

31 products

Check your exposure

Who says so?

4 sources

cnnvd · enisa_euvd · fstec_bdu · cert_bund

EPSS · scored 2026-10-27

LookupCol.c in X.Org X through X11R7.7 and libX11 before 1.7.1 might allow remote attackers to execute arbitrary code. The libX11 XLookupColor request (intended for server-side color lookup) contains a flaw allowing a client to send color-name requests with a name longer than the maximum size allowed by the protocol (and also longer than the maximum packet size for normal-sized packets). The user-controlled data exceeding the maximum size is then interpreted by the server as additional X protocol requests and executed, e.g., to disable X server authorization completely. For example, if the victim encounters malicious terminal control sequences for color codes, then the attacker may be able to take full control of the running graphical session.

cvss

Technical severity, 0–10. One row per scoring source.

9.8

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · low–critical · 3.3–9.8

v2.07.5highAV:N/AC:L/Au:N/C:P/I:P/A:Pprimary · NVD / NIST USexploitability 10 · impact 6.4

v3.19.8criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hprimary · NVD / NIST USexploitability 3.9 · impact 5.9

v3.13.3lowAV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:Lsecondary · FSTEC (BDU) RU

v3.19criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:Usecondary · CVSS-BT (t0sche)

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-120USprimaryCWE-20US

affected products (31)

Products and version ranges known to be affected.

Juniper Contrail Service Orchestrationall versionscert_bundDEcpe:/a:juniper:contrail_service_orchestration:-
Juniper Junos Space <21.3R1all versionscert_bundDE
Juniper Junos Space Security Director <24.1R4all versionscert_bundDE
Juniper Junos Space≤ Security Director <24.1R4cert_bundDE
Juniper Junos Space< 21.3R1cert_bundDE
n/a n/a≤ n/aenisa_euvdEU
Canonical Ltd. Ubuntu≤ 21.04fstec_bduRU
Canonical Ltd. Ubuntu≤ 18.04 LTSfstec_bduRU
Canonical Ltd. Ubuntu≤ 14.04 ESMfstec_bduRU
Canonical Ltd. Ubuntu≤ 20.04 LTSfstec_bduRU
Canonical Ltd. Ubuntu≤ 20.10fstec_bduRU
Canonical Ltd. Ubuntu≤ 16.04 ESMfstec_bduRU
Red Hat Inc. Red Hat Enterprise Linux≤ 7fstec_bduRU
Red Hat Inc. Red Hat Enterprise Linux≤ 8fstec_bduRU
X.Org Foundation Xlib (libX11)1.0.99.1 → 1.7.0fstec_bduRU
АО «ИВК» Альт 8 СПall versionsfstec_bduRU
АО «Концерн ВНИИНС» ОС ОН «Стрелец»≤ 16.01.2023fstec_bduRU
АО «НППКТ» ОСОН ОСнова Оnyx≤ 2.1fstec_bduRU
АО «НТЦ ИТ РОСА» ROSA Virtualization≤ 2.1fstec_bduRU
АО «НТЦ ИТ РОСА» ROSA Virtualization 3.0≤ 3.0fstec_bduRU

showing 20 of 31

advisories (2)

Vendor and ecosystem advisories describing this.

WID-SEC-W-2023-0063Juniper Junos Space: Mehrere SchwachstellenDeutsch2022-01-12csaf · cert_bundDE
Ein Angreifer aus dem angrenzenden Netzwerk oder ein entfernter anonymer, authentisierter oder lokaler Angreifer kann mehrere Schwachstellen in Juniper Junos Space ausnutzen, um Sicherheitsmaßnahmen zu umgehen, vertrauliche Informationen offenzulegen, einen Denial-of-Service-Zustand auszulösen, beliebigen Code auszuführen und seine Privilegien zu erweitern.
WID-SEC-W-2024-1591Juniper JUNOS: Mehrere SchwachstellenDeutsch2024-07-10csaf · cert_bundDE
Ein Angreifer kann mehrere Schwachstellen in Juniper JUNOS ausnutzen, um einen Denial of Service zu verursachen, Informationen offenzulegen, Privilegien zu erweitern und Sicherheitsmechanismen inklusive zu umgehen.

also known as (4)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd fstec_bdu cert_bund NVD CVE.org MITRE

published 2021-05-27modified 2026-06-17

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references (93)

External citations — patches, advisories, analysis.

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