Bug 2555059 (CVE-2026-98777)

Summary: CVE-2026-98777 kernel: binder: fix leaked fd fixups on TF_UPDATE_TXN supersede
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's Android Binder inter-process communication (IPC) driver. When an asynchronous transaction supersedes an earlier pending transaction in a frozen process, the kernel frees the outdated transaction without releasing associated file descriptor references. A local user can exploit this vulnerability to persistently leak file objects in kernel memory, ultimately leading to a denial of service (DoS) through system resource exhaustion.
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Description OSIDB Bzimport 2026-10-18 15:52:07 UTC 
In the Linux kernel, the following vulnerability has been resolved:

binder: fix leaked fd fixups on TF_UPDATE_TXN supersede

When a TF_UPDATE_TXN transaction supersedes a pending async transaction
in a frozen process, the outdated transaction is freed with kfree()
directly. This skips binder_free_txn_fixups(), leaking all
binder_txn_fd_fixup entries and their fget()'d struct file references.

The leaked file refcounts never reach zero, so the struct file objects
are permanently pinned in memory. They survive process exit and
accumulate across invocations until file-max exhaustion.

Every other transaction cleanup path (binder_free_transaction(),
binder_transaction() error paths, binder_release_work()) correctly
calls binder_free_txn_fixups(). Add the missing call before kfree()
in the t_outdated cleanup block.
Comment 1 Mauro Matteo Cascella 2026-10-23 07:41:09 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98777.mbox