{"id":"CVE-2026-43324","state":"PUBLISHED","title":"USB: dummy-hcd: Fix interrupt synchronization error","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nUSB: dummy-hcd: Fix interrupt synchronization error\n\nThis fixes an error in synchronization in the dummy-hcd driver.  The\nerror has a somewhat involved history.  The synchronization mechanism\nwas introduced by commit 7dbd8f4cabd9 (\"USB: dummy-hcd: Fix erroneous\nsynchronization change\"), which added an emulated \"interrupts enabled\"\nflag together with code emulating synchronize_irq() (it waits until\nall current handler callbacks have returned).\n\nBut the emulated interrupt-disable occurred too late, after the driver\ncontaining the handler callback routines had been told that it was\nunbound and no more callbacks would occur.  Commit 4a5d797a9f9c (\"usb:\ngadget: dummy_hcd: fix gpf in gadget_setup\") tried to fix this by\nmoving the synchronize_irq() emulation code from dummy_stop() to\ndummy_pullup(), which runs before the unbind callback.\n\nThere still were races, though, because the emulated interrupt-disable\nstill occurred too late.  It couldn't be moved to dummy_pullup(),\nbecause that routine can be called for reasons other than an impending\nunbind.  Therefore commits 7dc0c55e9f30 (\"USB: UDC core: Add\nudc_async_callbacks gadget op\") and 04145a03db9d (\"USB: UDC: Implement\nudc_async_callbacks in dummy-hcd\") added an API allowing the UDC core\nto tell dummy-hcd exactly when emulated interrupts and their callbacks\nshould be disabled.\n\nThat brings us to the current state of things, which is still wrong\nbecause the emulated synchronize_irq() occurs before the emulated\ninterrupt-disable!  That's no good, beause it means that more emulated\ninterrupts can occur after the synchronize_irq() emulation has run,\nleading to the possibility that a callback handler may be running when\nthe gadget driver is unbound.\n\nTo fix this, we have to move the synchronize_irq() emulation code yet\nagain, to the dummy_udc_async_callbacks() routine, which takes care of\nenabling and disabling emulated interrupt requests.  The\nsynchronization will now run immediately after emulated interrupts are\ndisabled, which is where it belongs.","publishedAt":"2026-05-08T13:31:08.850Z","updatedAt":"2026-08-05T12:27:14.134Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"04145a03db9d78469e0817ab3a767c76c0fb0947","status":"affected","lessThan":"d847f375b1bcea713143bc02720d13d2d01b012a","versionType":"git"},{"version":"04145a03db9d78469e0817ab3a767c76c0fb0947","status":"affected","lessThan":"cbf7df5e5d27cd5bea92ee9a75a4b28dbcc718d4","versionType":"git"},{"version":"04145a03db9d78469e0817ab3a767c76c0fb0947","status":"affected","lessThan":"5aa776c8615bea3b1eaeec87b0788375800ead4f","versionType":"git"},{"version":"04145a03db9d78469e0817ab3a767c76c0fb0947","status":"affected","lessThan":"94d4fab1dd9e64f45449bcc7d6a5acf796b13015","versionType":"git"},{"version":"04145a03db9d78469e0817ab3a767c76c0fb0947","status":"affected","lessThan":"5687a09776069bd915560021c9728ca528440128","versionType":"git"},{"version":"04145a03db9d78469e0817ab3a767c76c0fb0947","status":"affected","lessThan":"8bcd80219d8e10e660bf29b20e41bb8beb4e4cb7","versionType":"git"},{"version":"04145a03db9d78469e0817ab3a767c76c0fb0947","status":"affected","lessThan":"2ca9e46f8f1f5a297eb0ac83f79d35d5b3a02541","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/usb/gadget/udc/dummy_hcd.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.14","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.14","versionType":"semver"},{"version":"5.15.203","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.168","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.134","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.81","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.22","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.12","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/usb/gadget/udc/dummy_hcd.c"]}],"references":["https://git.kernel.org/stable/c/d847f375b1bcea713143bc02720d13d2d01b012a","https://git.kernel.org/stable/c/cbf7df5e5d27cd5bea92ee9a75a4b28dbcc718d4","https://git.kernel.org/stable/c/5aa776c8615bea3b1eaeec87b0788375800ead4f","https://git.kernel.org/stable/c/94d4fab1dd9e64f45449bcc7d6a5acf796b13015","https://git.kernel.org/stable/c/5687a09776069bd915560021c9728ca528440128","https://git.kernel.org/stable/c/8bcd80219d8e10e660bf29b20e41bb8beb4e4cb7","https://git.kernel.org/stable/c/2ca9e46f8f1f5a297eb0ac83f79d35d5b3a02541"],"weaknesses":[],"ingestedAt":"2026-10-29T20:11:57.932Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/43xxx/CVE-2026-43324.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-43324","state":"PUBLISHED","datePublished":"2026-05-08T13:31:08.850Z","dateUpdated":"2026-08-05T12:27:14.134Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-05-01T14:12:56.002Z"},"containers":{"cna":{"title":"USB: dummy-hcd: Fix interrupt synchronization error","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nUSB: dummy-hcd: Fix interrupt synchronization error\n\nThis fixes an error in synchronization in the dummy-hcd driver.  The\nerror has a somewhat involved history.  The synchronization mechanism\nwas introduced by commit 7dbd8f4cabd9 (\"USB: dummy-hcd: Fix erroneous\nsynchronization change\"), which added an emulated \"interrupts enabled\"\nflag together with code emulating synchronize_irq() (it waits until\nall current handler callbacks have returned).\n\nBut the emulated interrupt-disable occurred too late, after the driver\ncontaining the handler callback routines had been told that it was\nunbound and no more callbacks would occur.  Commit 4a5d797a9f9c (\"usb:\ngadget: dummy_hcd: fix gpf in gadget_setup\") tried to fix this by\nmoving the synchronize_irq() emulation code from dummy_stop() to\ndummy_pullup(), which runs before the unbind callback.\n\nThere still were races, though, because the emulated interrupt-disable\nstill occurred too late.  It couldn't be moved to dummy_pullup(),\nbecause that routine can be called for reasons other than an impending\nunbind.  Therefore commits 7dc0c55e9f30 (\"USB: UDC core: Add\nudc_async_callbacks gadget op\") and 04145a03db9d (\"USB: UDC: Implement\nudc_async_callbacks in dummy-hcd\") added an API allowing the UDC core\nto tell dummy-hcd exactly when emulated interrupts and their callbacks\nshould be disabled.\n\nThat brings us to the current state of things, which is still wrong\nbecause the emulated synchronize_irq() occurs before the emulated\ninterrupt-disable!  That's no good, beause it means that more emulated\ninterrupts can occur after the synchronize_irq() emulation has run,\nleading to the possibility that a callback handler may be running when\nthe gadget driver is unbound.\n\nTo fix this, we have to move the synchronize_irq() emulation code yet\nagain, to the dummy_udc_async_callbacks() routine, which takes care of\nenabling and disabling emulated interrupt requests.  The\nsynchronization will now run immediately after emulated interrupts are\ndisabled, which is where it belongs."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"04145a03db9d78469e0817ab3a767c76c0fb0947","status":"affected","lessThan":"d847f375b1bcea713143bc02720d13d2d01b012a","versionType":"git"},{"version":"04145a03db9d78469e0817ab3a767c76c0fb0947","status":"affected","lessThan":"cbf7df5e5d27cd5bea92ee9a75a4b28dbcc718d4","versionType":"git"},{"version":"04145a03db9d78469e0817ab3a767c76c0fb0947","status":"affected","lessThan":"5aa776c8615bea3b1eaeec87b0788375800ead4f","versionType":"git"},{"version":"04145a03db9d78469e0817ab3a767c76c0fb0947","status":"affected","lessThan":"94d4fab1dd9e64f45449bcc7d6a5acf796b13015","versionType":"git"},{"version":"04145a03db9d78469e0817ab3a767c76c0fb0947","status":"affected","lessThan":"5687a09776069bd915560021c9728ca528440128","versionType":"git"},{"version":"04145a03db9d78469e0817ab3a767c76c0fb0947","status":"affected","lessThan":"8bcd80219d8e10e660bf29b20e41bb8beb4e4cb7","versionType":"git"},{"version":"04145a03db9d78469e0817ab3a767c76c0fb0947","status":"affected","lessThan":"2ca9e46f8f1f5a297eb0ac83f79d35d5b3a02541","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/usb/gadget/udc/dummy_hcd.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.14","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.14","versionType":"semver"},{"version":"5.15.203","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.168","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.134","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.81","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.22","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.12","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/usb/gadget/udc/dummy_hcd.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/d847f375b1bcea713143bc02720d13d2d01b012a"},{"url":"https://git.kernel.org/stable/c/cbf7df5e5d27cd5bea92ee9a75a4b28dbcc718d4"},{"url":"https://git.kernel.org/stable/c/5aa776c8615bea3b1eaeec87b0788375800ead4f"},{"url":"https://git.kernel.org/stable/c/94d4fab1dd9e64f45449bcc7d6a5acf796b13015"},{"url":"https://git.kernel.org/stable/c/5687a09776069bd915560021c9728ca528440128"},{"url":"https://git.kernel.org/stable/c/8bcd80219d8e10e660bf29b20e41bb8beb4e4cb7"},{"url":"https://git.kernel.org/stable/c/2ca9e46f8f1f5a297eb0ac83f79d35d5b3a02541"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The vulnerable dummy-hcd path is reached through local USB gadget/host emulator interfaces such as raw-gadget, usbfs, configfs, or sysfs unbind paths. It is not network-reachable and dummy-hcd is an in-kernel emulator rather than a physically attached USB device.\nAC:L - Although this is a race, a local attacker can drive both sides by generating emulated USB activity while triggering gadget driver unbind, and the race can be retried. There are no special external conditions beyond attacker-controlled timing.\nPR:L - Exploitation requires local access to the configured dummy-hcd/gadget userspace interfaces, but the relevant raw-gadget and usbfs paths do not themselves impose a kernel capability check once accessible. When uncertain between root-only setup and normal local device access, the higher-severity PR:L is appropriate.\nUI:N - No victim action is needed after the attacker has local access to the relevant device interfaces. The attacker can trigger emulated USB callbacks and unbind locally.\nS:U - The impact remains within the same kernel security authority. This is a standard local kernel memory-safety/availability issue, not a VM escape or cross-authority boundary violation.\nC:H - The synchronization bug can allow asynchronous gadget callbacks to run after or during gadget driver unbind, leaving callback code operating on stale or cleared gadget-driver state. This is a use-after-unbind/use-after-free class condition, so kernel memory disclosure is a defensible worst-case impact.\nI:H - Callback execution against freed or invalid gadget-driver state can be leveraged as kernel memory corruption rather than merely a clean failure. Under the required higher-severity rule, a UAF-style kernel race supports potential arbitrary write or code execution.\nA:H - At minimum, the race can crash the kernel through NULL dereference or stale pointer use in gadget callbacks, as related dummy-hcd synchronization bugs have done. Kernel oops/panic is high availability impact."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:27:14.134Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.14","versionEndExcluding":"5.15.203"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.14","versionEndExcluding":"6.1.168"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.14","versionEndExcluding":"6.6.134"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.14","versionEndExcluding":"6.12.81"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.14","versionEndExcluding":"6.18.22"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.14","versionEndExcluding":"6.19.12"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.14","versionEndExcluding":"7.0"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}