Bug 2545164 (CVE-2026-93521)
| Summary: | CVE-2026-93521 xorg-x11-server: xorg-x11-server: Privilege escalation via crafted RandR provider property requests | ||
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| Product: | [Other] Security Response | Reporter: | OSIDB Bzimport <bzimport> |
| Component: | vulnerability | Assignee: | Product Security DevOps Team <prodsec-dev> |
| Status: | NEW --- | QA Contact: | |
| Severity: | high | Docs Contact: | |
| Priority: | high | ||
| Version: | unspecified | CC: | rhel-process-autobot, security-response-team, watson-tool-maintainers |
| Target Milestone: | --- | Keywords: | Security |
| Target Release: | --- | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | --- | |
| Doc Text: |
A flaw was found in xorg-x11-server. The X server incorrectly calculates buffer sizes and memory offsets when prepending or appending data to RandR (Resize and Rotate extension) provider properties. A local attacker can exploit this vulnerability by sending specially crafted property update requests, causing memory corruption. This flaw could allow an attacker to escalate privileges or cause a denial of service (DoS) by crashing the X server.
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Story Points: | --- |
| Clone Of: | Environment: | ||
| Last Closed: | Type: | --- | |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
| Bug Depends On: | 2559845, 2559852, 2559858 | ||
| Bug Blocks: | |||
| Deadline: | 2026-10-07 | ||
This issue has been addressed in the following products: Red Hat Enterprise Linux 9 Via RHSA-2026:82015 https://access.redhat.com/errata/RHSA-2026:82015 This issue has been addressed in the following products: Red Hat Enterprise Linux 10 Via RHSA-2026:85191 https://access.redhat.com/errata/RHSA-2026:85191 This issue has been addressed in the following products: Red Hat Enterprise Linux 9 Via RHSA-2026:85193 https://access.redhat.com/errata/RHSA-2026:85193 This issue has been addressed in the following products: Red Hat Enterprise Linux 8 Via RHSA-2026:86907 https://access.redhat.com/errata/RHSA-2026:86907 This issue has been addressed in the following products: Red Hat Enterprise Linux 8 Via RHSA-2026:89747 https://access.redhat.com/errata/RHSA-2026:89747 |
RRChangeProviderProperty() has two bugs in the PropModePrepend case: 1. new_value.size is set to 'len' (the new data length) instead of 'total_len' (len + prop_value->size), losing track of the existing data. This also affects PropModeAppend. 2. The old_data offset is computed using prop_value->size instead of len. For PrependMode, the layout should be [new(len)][old(size)], so old_data should start at len * size_in_bytes. These bugs are analogous to the ones fixed in RRChangeOutputProperty(), see commit 541ab2ecd41d ("Xi/randr: fix handling of PropModeAppend/Prepend"). This vulnerability was discovered by: Anonymous working with TrendAI Zero Day Initiative ZDI-CAN-31944