usb: cdc-acm: Check control transfer buffer size before access
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Code execution
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Partial Red Hat: 3 without a fix
Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat. Impact type from CWE-787 and the CVSS impact.
Summary
In the Linux kernel, the following vulnerability has been resolved: usb: cdc-acm: Check control transfer buffer size before access If the first fragment is shorter than struct usb_cdc_notification, we can't calculate an expected_size. Log an error and discard the notification instead of reading lengths from memory outside the received data, which can lead to memory corruption when the expected_size decreases between fragments, causing `expected_size - acm->nb_index` to wrap. This issue has been present since the beginning of git history; however, it only leads to memory corruption since commit ea2583529cd1 ("cdc-acm: reassemble fragmented notifications"). A mitigating factor is that acm_ctrl_irq() can only execute after userspace has opened /dev/ttyACM*; but if ModemManager is running, ModemManager will do that automatically depending on the USB device's vendor/product IDs and its other interfaces.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Linux | Linux | 2.6.12 and later | 5.4.291, 5.10.235, 5.15.179, 6.1.129, 6.6.79, 6.12.16, 6.13.4, 6.14 | Patch available | CNA |
- Linux VendorLinux Affected 2.6.12 and later Fixed in 5.4.291, 5.10.235, 5.15.179, 6.1.129, 6.6.79, 6.12.16, 6.13.4, 6.14 Patch available CNA
CPE configurations NVD · 8
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | 2.6.13 to before 5.4.291; 5.5 to before 5.10.235; 5.11 to before 5.15.179; 5.16 to before 6.1.129; 6.2 to before 6.6.79; 6.7 to before 6.12.16; 6.13 to before 6.13.4 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:2.6.12:-:*:*:*:*:*:* | 2.6.12 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:2.6.12:rc2:*:*:*:*:*:* | 2.6.12 rc2 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:2.6.12:rc3:*:*:*:*:*:* | 2.6.12 rc3 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:2.6.12:rc4:*:*:*:*:*:* | 2.6.12 rc4 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:2.6.12:rc5:*:*:*:*:*:* | 2.6.12 rc5 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:6.14:rc1:*:*:*:*:*:* | 6.14 rc1 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:6.14:rc2:*:*:*:*:*:* | 6.14 rc2 | Vulnerable | Linux |
- cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions 2.6.13 to before 5.4.291; 5.5 to before 5.10.235; 5.11 to before 5.15.179; 5.16 to before 6.1.129; 6.2 to before 6.6.79; 6.7 to before 6.12.16; 6.13 to before 6.13.4 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:2.6.12:-:*:*:*:*:*:* Versions 2.6.12 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:2.6.12:rc2:*:*:*:*:*:* Versions 2.6.12 rc2 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:2.6.12:rc3:*:*:*:*:*:* Versions 2.6.12 rc3 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:2.6.12:rc4:*:*:*:*:*:* Versions 2.6.12 rc4 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:2.6.12:rc5:*:*:*:*:*:* Versions 2.6.12 rc5 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:6.14:rc1:*:*:*:*:*:* Versions 6.14 rc1 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:6.14:rc2:*:*:*:*:*:* Versions 6.14 rc2 Vulnerable ·Linux
Remediation
- Fix · CNA Linux (Linux) Fixed in 5.4.291, 5.10.235, 5.15.179, 6.1.129, 6.6.79, 6.12.16, 6.13.4, 6.14
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 6 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux 7 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux 8 | Affected | No fix planned: Out of support scope |
Not affected: 2 products
- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 9
Timeline
- 2026-10-02 Threatist record created from CVE-2025-21704
- 2026-10-03 Alias added: GHSA-48g3-w2gf-xjrv
References
Patch 8
- https://git.kernel.org/stable/c/a4e1ae5c0533964170197e4fb4f33bc8c1db5cd2
- https://git.kernel.org/stable/c/90dd2f1b7342b9a671a5ea4160f408037b92b118
- https://git.kernel.org/stable/c/871619c2b78fdfe05afb4e8ba548678687beb812
- https://git.kernel.org/stable/c/7828e9363ac4d23b02419bf2a45b9f1d9fb35646
- https://git.kernel.org/stable/c/6abb510251e75f875797d8983a830e6731fa281c
- https://git.kernel.org/stable/c/f64079bef6a8a7823358c3f352ea29a617844636
- https://git.kernel.org/stable/c/383d516a0ebc8641372b521c8cb717f0f1834831
- https://git.kernel.org/stable/c/e563b01208f4d1f609bcab13333b6c0e24ce6a01
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Sources
- CVE-2025-21704 · CVE Program
- CVE-2025-21704 · NVD
- FIRST EPSS
- GHSA-48g3-w2gf-xjrv · GitHub Advisory Database · CC BY 4.0
- CVE-2025-21704 · Red Hat security data · CC BY 4.0
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