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CVE-2026-46167 Linux CVE debrief

A vulnerability in the Linux kernel's USB printer driver (usblp) allows information disclosure via an uninitialized heap memory leak. The statusbuf buffer, allocated via kmalloc(8) at probe time, is never initialized before the first LPGETSTATUS ioctl. When usblp_read_status() requests 1 byte and a malicious or misbehaving USB printer responds with zero bytes, the driver returns one byte of stale heap memory to the ioctl caller. This stale data is sign-extended into an int and copied to userspace via copy_to_user(). The vulnerability exists because usblp_ctrl_msg() collapses the usb_control_msg() return value to 0/-errno, discarding the actual bytes transferred, preventing proper short-read detection. The fix initializes the buffer at allocation time to prevent information leakage.

Vendor
Linux
Product
Unknown
CVSS
MEDIUM 5.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-05-28
Original CVE updated
2026-06-10
Advisory published
2026-05-28
Advisory updated
2026-06-10

Who should care

Linux system administrators, kernel maintainers, organizations with physical security concerns regarding USB device attachment, embedded systems using USB printers, security teams tracking kernel information disclosure vulnerabilities

Technical summary

The usblp driver in the Linux kernel contains an information disclosure vulnerability in the LPGETSTATUS ioctl handler. The statusbuf buffer (8 bytes, kmalloc'd at probe) is not initialized before first use. When usblp_read_status() performs a USB control message requesting 1 byte, and the device returns 0 bytes (short read), the driver fails to detect this condition because usblp_ctrl_msg() discards the actual transfer count. The uninitialized first byte of statusbuf is then sign-extended and returned to userspace. The fix zero-initializes statusbuf at allocation, ensuring no heap memory leakage occurs on short reads.

Defensive priority

medium

Recommended defensive actions

  • Apply kernel patches from stable branches when available for your distribution
  • Verify usblp driver is not loaded if USB printer support is not required
  • Monitor for distribution security advisories for kernel updates
  • Review systems with physical USB access for potential malicious device attachment

Evidence notes

Vulnerability description confirms kmalloc(8) allocation without initialization at probe time. The LPGETSTATUS ioctl path copies statusbuf content to userspace. Malicious printer with zero-byte response triggers leak of uninitialized heap memory. Fix commit initializes buffer at allocation. Multiple stable kernel branch commits provided indicate backporting to supported releases.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-46167 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-46167

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-46167 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-46167

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/6b0e7438e31c74b01514d31ff35c1e688c4baaba

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/762a6ccf391db0d629e590a803a3a2231e17dd3f

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/a502b997668401a6821501fc98b7f9220f9b6ff2

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/b38e53cbfb9d84732e5984fbd73e128d592415c5

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/d06d937b0a4cdb8867f04275c8100a8b943da31a

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.