CVE Feed

    Dashboard / CVE / CVE-2021-31535

    CVE-2021-31535

    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.

    Published:May 18, 2021
    Last Modified:Nov 21, 2024
    EPS:May 27, 2021
    EPSS Score:0.02601
    CVSS Score:9.8

    Affected Products

    Vendor
    Fedoraproject
    Product
    Fedora
    Vendor
    Redhat
    Product
    Ansible Automation Platform
    Vendor
    Redhat
    Product
    Enterprise Linux
    Vendor
    X.org
    Product
    Libx11
    Vendor
    X.org
    Product
    X Window System

    Exploits

    http://packetstormsecurity.com/files/162737/libX11-Insufficient-Length-Check-Injection.htmlhttps://unparalleled.eu/blog/2021/20210518-using-xterm-to-navigate-the-huge-color-space/https://unparalleled.eu/publications/2021/advisory-unpar-2021-1.txthttp://packetstormsecurity.com/files/162737/libX11-Insufficient-Length-Check-Injection.htmlhttps://unparalleled.eu/blog/2021/20210518-using-xterm-to-navigate-the-huge-color-space/https://unparalleled.eu/publications/2021/advisory-unpar-2021-1.txt

    Common Attack Pattern Enumeration and Classification (CAPEC)

    CAPEC-10 Buffer Overflow via Environment Variables
    CAPEC-100 Overflow Buffers
    CAPEC-101 Server Side Include (SSI) Injection
    CAPEC-104 Cross Zone Scripting
    CAPEC-108 Command Line Execution through SQL Injection
    CAPEC-109 Object Relational Mapping Injection
    CAPEC-110 SQL Injection through SOAP Parameter Tampering
    CAPEC-120 Double Encoding
    CAPEC-13 Subverting Environment Variable Values
    CAPEC-135 Format String Injection
    CAPEC-136 LDAP Injection
    CAPEC-14 Client-side Injection-induced Buffer Overflow
    CAPEC-15 Command Delimiters
    CAPEC-153 Input Data Manipulation
    CAPEC-182 Flash Injection
    CAPEC-183 IMAP/SMTP Command Injection
    CAPEC-209 XSS Using MIME Type Mismatch
    CAPEC-22 Exploiting Trust in Client
    CAPEC-23 File Content Injection
    CAPEC-230 Serialized Data with Nested Payloads
    CAPEC-231 Oversized Serialized Data Payloads
    CAPEC-24 Filter Failure through Buffer Overflow
    CAPEC-248 Command Injection
    CAPEC-250 XML Injection
    CAPEC-261 Fuzzing for garnering other adjacent user/sensitive data
    CAPEC-267 Leverage Alternate Encoding
    CAPEC-28 Fuzzing
    CAPEC-3 Using Leading 'Ghost' Character Sequences to Bypass Input Filters
    CAPEC-31 Accessing/Intercepting/Modifying HTTP Cookies
    CAPEC-40 Manipulating Writeable Terminal Devices
    CAPEC-42 MIME Conversion
    CAPEC-43 Exploiting Multiple Input Interpretation Layers
    CAPEC-44 Overflow Binary Resource File
    CAPEC-45 Buffer Overflow via Symbolic Links
    CAPEC-46 Overflow Variables and Tags
    CAPEC-47 Buffer Overflow via Parameter Expansion
    CAPEC-473 Signature Spoof
    CAPEC-52 Embedding NULL Bytes
    CAPEC-53 Postfix, Null Terminate, and Backslash
    CAPEC-588 DOM-Based XSS
    CAPEC-63 Cross-Site Scripting (XSS)
    CAPEC-64 Using Slashes and URL Encoding Combined to Bypass Validation Logic
    CAPEC-664 Server Side Request Forgery
    CAPEC-67 String Format Overflow in syslog()
    CAPEC-7 Blind SQL Injection
    CAPEC-71 Using Unicode Encoding to Bypass Validation Logic
    CAPEC-72 URL Encoding
    CAPEC-73 User-Controlled Filename
    CAPEC-75 Manipulating Writeable Configuration Files
    CAPEC-76 Manipulating Web Input to File System Calls
    CAPEC-78 Using Escaped Slashes in Alternate Encoding
    CAPEC-79 Using Slashes in Alternate Encoding
    CAPEC-8 Buffer Overflow in an API Call
    CAPEC-80 Using UTF-8 Encoding to Bypass Validation Logic
    CAPEC-81 Web Server Logs Tampering
    CAPEC-83 XPath Injection
    CAPEC-85 AJAX Footprinting
    CAPEC-88 OS Command Injection
    CAPEC-9 Buffer Overflow in Local Command-Line Utilities
    CAPEC-92 Forced Integer Overflow

    Related CVEs

    CVE-2026-54231 (CVSS 5.5) — A content injection vulnerability was found in the ABRT post-create event handler scripts in libreport. The ev…
    CVE-2026-54230 (CVSS 7) — A symlink following vulnerability was found in the ABRT post-create event handler scripts in libreport. Event …
    CVE-2026-35094 (CVSS 3.3) — A flaw was found in libinput. An attacker capable of deploying a Lua plugin file in specific system directorie…
    CVE-2026-35093 (CVSS 8.8) — A flaw was found in libinput. A local attacker who can place a specially crafted Lua bytecode file in certain …
    CVE-2024-3056 (CVSS 7.7) — A flaw was found in Podman. This issue may allow an attacker to create a specially crafted container that, whe…
    CVE-2024-6293 (CVSS 8.8) — Use after free in Dawn in Google Chrome prior to 126.0.6478.126 allowed a remote attacker to potentially explo…
    CVE-2024-6292 (CVSS 8.8) — Use after free in Dawn in Google Chrome prior to 126.0.6478.126 allowed a remote attacker to potentially explo…
    CVE-2024-6291 (CVSS 8.8) — Use after free in Swiftshader in Google Chrome prior to 126.0.6478.126 allowed a remote attacker to potentiall…
    CVE-2024-6290 (CVSS 8.8) — Use after free in Dawn in Google Chrome prior to 126.0.6478.126 allowed a remote attacker to potentially explo…
    CVE-2024-38277 (CVSS 5.4) — A unique key should be generated for a user's QR login key and their auto-login key, so the same key cannot be…

    References

    http://packetstormsecurity.com/files/162737/libX11-Insufficient-Length-Check-Injection.html
    http://seclists.org/fulldisclosure/2021/May/52
    http://www.openwall.com/lists/oss-security/2021/05/18/2
    https://gitlab.freedesktop.org/xorg/lib/libx11/-/commit/8d2e02ae650f00c4a53deb625211a0527126c605
    https://lists.apache.org/thread.html/r61db8e7dcb56dc000a5387a88f7a473bacec5ee01b9ff3f55308aacc%40%3Cdev.kafka.apache.org%3E
    https://lists.apache.org/thread.html/r61db8e7dcb56dc000a5387a88f7a473bacec5ee01b9ff3f55308aacc%40%3Cusers.kafka.apache.org%3E
    https://lists.apache.org/thread.html/rbf4ce74b0d1fa9810dec50ba3ace0caeea677af7c27a97111c06ccb7%40%3Cdev.kafka.apache.org%3E
    https://lists.apache.org/thread.html/rbf4ce74b0d1fa9810dec50ba3ace0caeea677af7c27a97111c06ccb7%40%3Cusers.kafka.apache.org%3E
    https://lists.debian.org/debian-lts-announce/2021/05/msg00021.html
    https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TEOT4RLB76RVPJQKGGTIKTBIOLHX2NR6/
    https://lists.freedesktop.org/archives/xorg/
    https://lists.x.org/archives/xorg-announce/2021-May/003088.html
    https://security.gentoo.org/glsa/202105-16
    https://security.netapp.com/advisory/ntap-20210813-0001/
    https://unparalleled.eu/blog/2021/20210518-using-xterm-to-navigate-the-huge-color-space/
    https://unparalleled.eu/publications/2021/advisory-unpar-2021-1.txt
    https://www.debian.org/security/2021/dsa-4920
    https://www.openwall.com/lists/oss-security/2021/05/18/2
    https://www.openwall.com/lists/oss-security/2021/05/18/3
    http://packetstormsecurity.com/files/162737/libX11-Insufficient-Length-Check-Injection.html
    http://seclists.org/fulldisclosure/2021/May/52
    http://www.openwall.com/lists/oss-security/2021/05/18/2
    https://gitlab.freedesktop.org/xorg/lib/libx11/-/commit/8d2e02ae650f00c4a53deb625211a0527126c605
    https://lists.apache.org/thread.html/r61db8e7dcb56dc000a5387a88f7a473bacec5ee01b9ff3f55308aacc%40%3Cdev.kafka.apache.org%3E
    https://lists.apache.org/thread.html/r61db8e7dcb56dc000a5387a88f7a473bacec5ee01b9ff3f55308aacc%40%3Cusers.kafka.apache.org%3E
    https://lists.apache.org/thread.html/rbf4ce74b0d1fa9810dec50ba3ace0caeea677af7c27a97111c06ccb7%40%3Cdev.kafka.apache.org%3E
    https://lists.apache.org/thread.html/rbf4ce74b0d1fa9810dec50ba3ace0caeea677af7c27a97111c06ccb7%40%3Cusers.kafka.apache.org%3E
    https://lists.debian.org/debian-lts-announce/2021/05/msg00021.html
    https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TEOT4RLB76RVPJQKGGTIKTBIOLHX2NR6/
    https://lists.freedesktop.org/archives/xorg/
    https://lists.x.org/archives/xorg-announce/2021-May/003088.html
    https://security.gentoo.org/glsa/202105-16
    https://security.netapp.com/advisory/ntap-20210813-0001/
    https://unparalleled.eu/blog/2021/20210518-using-xterm-to-navigate-the-huge-color-space/
    https://unparalleled.eu/publications/2021/advisory-unpar-2021-1.txt
    https://www.debian.org/security/2021/dsa-4920
    https://www.openwall.com/lists/oss-security/2021/05/18/2
    https://www.openwall.com/lists/oss-security/2021/05/18/3

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High