CVE-2026-33999 | X.org X Server XKB Compatibility Map integer underflow (EUVD-2026-25229)

VDB-359150 · CVE-2026-33999 · EUVD-2026-25229 X.ORG X SERVER XKB COMPATIBILITY MAP INTEGER UNDERFLOW HISTORYDIFFRELATEJSONXMLCTI CVSS Meta Temp Score Current Exploit Price (≈) CTI Interest Score 7.8 $0-$5k 2.85 Summaryinfo A vulnerability categorized as critical has been discovered in X.org X Server. Affected by this vulnerability is an unknown functionality of the component XKB Compatibility Map Handler. Such manipulation leads to integer underflow. This vulnerability is referenced as CVE-2026-33999. The attack can only be performed from a local environment. No exploit is available. Detailsinfo A vulnerability was found in X.org X Server (affected version unknown) and classified as critical. Affected by this issue is an unknown functionality of the component XKB Compatibility Map Handler. The manipulation with an unknown input leads to a integer underflow vulnerability. Using CWE to declare the problem leads to CWE-191. The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result. Impacted is confidentiality, integrity, and availability. CVE summarizes: A flaw was found in the X.Org X server. This integer underflow vulnerability, specifically in the XKB compatibility map handling, allows an attacker with local or remote X11 server access to trigger a buffer read overrun. This can lead to memory-safety violations and potentially a denial of service (DoS) or other severe impacts. The advisory is available at access.redhat.com. This vulnerability is handled as CVE-2026-33999 since 03/25/2026. The exploitation is known to be easy. Local access is required to approach this attack. The technical details are unknown and an exploit is not available. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 04/23/2026). There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product. The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-25229). Productinfo Vendor X.org Name X Server License open-source Website Vendor: https://www.x.org/ CPE 2.3info 🔒 CPE 2.2info 🔒 CVSSv4info VulDB Vector: 🔒 VulDB Reliability: 🔍 CVSSv3info VulDB Meta Base Score: 7.8 VulDB Meta Temp Score: 7.8 VulDB Base Score: 7.8 VulDB Temp Score: 7.8 VulDB Vector: 🔒 VulDB Reliability: 🔍 CNA Base Score: 7.8 CNA Vector (redhat): 🔒 CVSSv2info Vector Complexity Authentication Confidentiality Integrity Availability Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock VulDB Base Score: 🔒 VulDB Temp Score: 🔒 VulDB Reliability: 🔍 Exploitinginfo Class: Integer underflow CWE: CWE-191 / CWE-189 CAPEC: 🔒 ATT&CK: 🔒 Physical: Partially Local: Yes Remote: No Availability: 🔒 Status: Not defined Price Prediction: 🔍 Current Price Estimation: 🔒 0-Day Unlock Unlock Unlock Unlock Today Unlock Unlock Unlock Unlock Threat Intelligenceinfo Interest: 🔍 Active Actors: 🔍 Active APT Groups: 🔍 Countermeasuresinfo Recommended: no mitigation known Status: 🔍 0-Day Time: 🔒 Timelineinfo 03/25/2026 CVE reserved 04/23/2026 +28 days Advisory disclosed 04/23/2026 +0 days VulDB entry created 04/23/2026 +0 days VulDB entry last update Sourcesinfo Vendor: x.org Advisory: access.redhat.com Status: Confirmed CVE: CVE-2026-33999 (🔒) GCVE (CVE): GCVE-0-2026-33999 GCVE (VulDB): GCVE-100-359150 EUVD: 🔒 Entryinfo Created: 04/23/2026 18:14 Updated: 04/23/2026 19:44 Changes: 04/23/2026 18:14 (60), 04/23/2026 19:44 (1) Complete: 🔍 Cache ID: 99:0E2:101 Discussion No comments yet. Languages: en. Please log in to comment. ◂ PreviousOverviewNext ▸