Skip to main content
Mallory
Critical

Privilege escalation via Arm TLBI completion ordering flaw

IdentifiersCVE-2025-10263CWE-269

CVE-2025-10263 is a critical Arm CPU erratum affecting multiple Arm C1, Neoverse, and Cortex cores. The issue arises from a timing/ordering condition during memory permission changes in which completion of certain memory accesses is not guaranteed by completion of a TLB invalidation (TLBI) and the associated synchronization barrier. As described by Arm and Xen, a broadcast TLBI on one processing element can complete before an affected store on another processing element has been globally observed under specific micro-architectural conditions. This can result in a write completing after page table or translation permissions have been changed to forbid writes to that location. In practice, software may still write to a previously writable location after the page tables or Stage 2 translation have been updated to revoke write access, potentially allowing writes to memory owned by a higher exception level. Xen notes the flaw may bypass Stage 1 translation, Stage 2 translation, or GPT protection, and does not affect reads.

Share:
For your environment

Are you exposed to this one?

Mallory correlates every CVE against your assets, your vendors, and active adversary campaigns. Know which vulnerabilities matter for you, not just which ones are loud.

ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation can allow unauthorized writes across privilege boundaries after write permissions have ostensibly been revoked, leading to privilege escalation. On affected systems generally, lower-privileged software may be able to write to resources owned by a higher exception level. In Xen on Arm environments, a malicious guest may be able to continue writing to memory after Xen changes Stage 2 permissions to prohibit writes, potentially escalating privileges to the hypervisor. This compromises isolation and can affect confidentiality, integrity, and availability depending on the targeted memory region.

Mitigation

If you can’t patch tonight, do this now.

No complete workaround is generally available beyond applying the vendor fixes/workarounds. Where immediate patching is not possible, reduce exposure by limiting use of affected multi-core Arm systems in high-risk virtualization or mixed-trust scenarios, especially Xen on Arm deployments where untrusted guests run alongside sensitive workloads. Because exploitation depends on permission changes and cross-core timing conditions, minimizing untrusted local code execution and guest access may reduce risk, but this does not eliminate the vulnerability.

Remediation

Patch, then assume compromise.

Apply vendor-provided fixes and software workarounds for affected platforms. Arm published a workaround for software performing TLB invalidation affecting Stage 1 or Stage 1+2 translations that requires an additional TLBI and DSB. For Xen, apply the published XSA-493 patch sets for xen-unstable or supported stable branches (including Xen 4.17 through 4.21) as applicable. For FreeBSD arm64, upgrade to a corrected supported branch or release/security version identified in FreeBSD-SA-26:31.arm64 and reboot. Linux and other downstreams should deploy the relevant kernel/platform patches implementing Arm's mitigation. Platform owners should also obtain any firmware, microcode, or vendor integration updates from Arm, OEMs, or SoC vendors where available.
PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType
FreebsdFreebsdapplication
Microsoft CorporationWindowsoperating_system

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

What this page doesn’t show

The version that knows your environment.

This page is what’s public. Mallory adds the parts that aren’t: which of your assets are affected, which adversaries are exploiting it right now, which detections to deploy, and what to do tonight.
Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity11

Community discussion across Reddit, Mastodon, and other social sources.