CVE-2026-53161 | misc: fastrpc: fix use-after-free of fastrpc_user in workqueue context

In the Linux kernel, the following vulnerability has been resolved: misc: fastrpc: fix use-after-free of fastrpc_user in workqueue context There is a race between fastrpc_device_release() and the workqueue that processes DSP responses. When the user closes the file descriptor, fastrpc_device_release() frees the fastrpc_user structure. Concurrently, an in-flight DSP invocation can complete and fastrpc_rpmsg_callback() schedules context cleanup via schedule_work(&ctx->put_work). If the workqueue runs fastrpc_context_free() in parallel with or after fastrpc_device_release() has freed the user structure, it dereferences the freed fastrpc_user. Depending on the state of the context at the time of the race, any one of the following accesses can be hit: 1. fastrpc_buf_free() calls fastrpc_ipa_to_dma_addr(buf->fl->cctx, ...) to strip the SID bits from the stored IOVA before passing the physical address to dma_free_coherent(). 2. fastrpc_free_map() reads map->fl->cctx->vmperms[0].vmid to reconstruct the source permission bitmask needed for the qcom_scm_assign_mem() call that returns memory from the DSP VM back to HLOS. 3. fastrpc_free_map() acquires map->fl->lock to safely remove the map node from the fl->maps list. The resulting use-after-free manifests as: pc : fastrpc_buf_free+0x38/0x80 [fastrpc] lr : fastrpc_context_free+0xa8/0x1b0 [fastrpc] fastrpc_context_free+0xa8/0x1b0 [fastrpc] fastrpc_context_put_wq+0x78/0xa0 [fastrpc] process_one_work+0x180/0x450 worker_thread+0x26c/0x388 Add kref-based reference counting to fastrpc_user. Have each invoke context take a reference on the user at allocation time and release it when the context is freed. Release the initial reference in fastrpc_device_release() at file close. Move the teardown of the user structure — freeing pending contexts, maps, mmaps, and the channel context reference — into the kref release callback fastrpc_user_free(), so that it runs only when the last reference is dropped, regardless of whether that happens at device close or after the final in-flight context completes.

Published: 2026-06-25 Last update: 2026-06-30 Assigner: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD Status：Awaiting Analysis，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-53161 is rated Low Risk (32.3/100): CVSS High severity, with low exploitation likelihood (EPSS 0.14%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-53161

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-28 0.18% 0.14% -0.05%
2 2026-06-25 — 0.18% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-53161

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.8 3.1 HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.8 5.9 416baaa9-dc9f-4396-8d5f-8c081fb06d67

Weakness enumeration for CVE-2026-53161

GitHub Security Advisory for CVE-2026-53161

GHSA-4v48-c98q-4vpc · Severity: high — In the Linux kernel, the following vulnerability has been resolved: misc: fastrpc: fix use-after...

OS Trackers for CVE-2026-53161

vendor priority summary link
debian not yet assigned CVE-2026-53161 not yet assigned priority: Debian including 1 source packages (linux), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 3, open 2. https://security-tracker.debian.org/tracker/CVE-2026-53161
redhat — — https://access.redhat.com/security/cve/CVE-2026-53161
suse medium CVE-2026-53161 severity moderate: SUSE including 20 source package names (cluster-md-kmp-default, dlm-kmp-default, …), 93 product×package rows across 22 product lines (SUSE Linux Enterprise High Availability Extension 15 SP7, SUSE Linux Enterprise Live Patching 12 SP5, … (22 product lines)): Known Not Affected 93. https://www.suse.com/security/cve/CVE-2026-53161/
ubuntu low CVE-2026-53161 low priority: Ubuntu including 161 source packages (linux, linux-allwinner-5.19, …), 1449 status rows across 9 suites (bionic, focal, jammy, noble, questing, resolute, trusty, upstream, xenial): DNE 1044, ignored 201, needed 93, released 87, not-affected 23, needs-triage 1. https://ubuntu.com/security/CVE-2026-53161

Affected software / configurations for CVE-2026-53161

Vendor Product Version Raw CPE
linux linux_kernel >= 5.1, < 5.10.259 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 5.1, < 5.15.210 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 5.1, < 6.1.176 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 5.1, < 6.6.143 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 5.1, < 6.12.94 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 5.1, < 6.18.36 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 5.1, < 7.0.13 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 5.1, < 7.1 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

References for CVE-2026-53161

cvelogic Threat Intelligence