CVE-2026-63895: Software Security Vulnerability Vulnerability

UNKNOWN
Advisory Identifier: GHSA-hqp4-gw43-6pcc
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Advisory Summary

CVE-2026-63895 is a security vulnerability vulnerability (General Security Weakness) affecting Software libraries in the Maven ecosystem. Remediation is available in the latest vendor maintenance releases.

CVE-2026-63895 at a Glance

CVE Identifier CVE-2026-63895
GHSA Identifier GHSA-hqp4-gw43-6pcc
Severity N/A
CVSS v3.1 Base Score N/A
CWE Classification General Security Weakness
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

How to Fix CVE-2026-63895

To remediate this vulnerability, upgrade all affected Software dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

mvn dependency:tree

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-63895, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree

Analyze the terminal output to locate any version of Software in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than the patched release), your application is affected.

Note: The mvn dependency:tree command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under General Security Weakness. In Software, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_fs: copy only received bytes on short ep0 read ffs_ep0_read() allocates its control-OUT data buffer with kmalloc() (not kzalloc) at the Length value from the Setup packet, then copies that full len to userspace regardless of how many bytes were actually received: data = kmalloc(len, GFP_KERNEL); ... ret = __ffs_ep0_queue_wait(ffs, data, len); if ((ret > 0) && (copy_to_user(buf, data, len))) ret = -EFAULT; __ffs_ep0_queue_wait() returns req->actual, which on a short control OUT transfer is strictly less than len. The copy_to_user() call still copies len bytes, so on a short OUT the last (len - ret) bytes of the kmalloc() buffer -- uninitialised slab residue -- are delivered to the FunctionFS daemon. Short ep0 OUT completions are specified USB control-transfer behavior and are produced by in-tree UDCs: * dwc2 continues on req->actual < req->length for ep0 DATA OUT (short-not-ok is the only ep0-OUT stall path). * aspeed_udc ends ep0 OUT on rx_len < ep->ep.maxpacket. * renesas_usbf logs "ep0 short packet" and completes the request. * dwc3 stalls on short IN but not on short OUT. A short ep0 OUT is therefore not evidence of a broken UDC; it is a normal condition f_fs has to cope with. The sibling gadgetfs implementation in drivers/usb/gadget/legacy/inode.c already does this correctly via min(len, dev->req->actual) before copy_to_user(). This patch brings f_fs.c to the same safe pattern rather than trimming at a defensive layer. The bug is reached from the FunctionFS device node, which in real deployments is owned by the privileged gadget daemon (adbd, UMS, composite gadget services, etc.); it is not reachable from unprivileged userspace. Linux host stacks normally reject short-wLength control OUTs before they reach the gadget, so reproducing this required a build that bypasses that host-side check. With the bypass in place, a 1-byte payload on a 64-byte Setup produces 63 bytes of non-canary slab residue in the daemon's read buffer. Fix by copying only ret (actually received) bytes to userspace.

References

NVD — CVE-2026-63895 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-63895
git.kernel.org/stable/c/23c1f7deb9... WEB
https://git.kernel.org/stable/c/23c1f7deb9dd8447ecde749850676302aa1e2bd3
git.kernel.org/stable/c/4e036c10e7... WEB
https://git.kernel.org/stable/c/4e036c10e7f4df5d951c69cc3697bc8e209c6d02
git.kernel.org/stable/c/607730a414... WEB
https://git.kernel.org/stable/c/607730a414773a7cbe3037a64a6c64e72689ff5e
git.kernel.org/stable/c/88874a19b2... WEB
https://git.kernel.org/stable/c/88874a19b2b093bfaaa1c0090fa536c44da8c08b
git.kernel.org/stable/c/90ccf5fb63... WEB
https://git.kernel.org/stable/c/90ccf5fb63243fae1b4b3200f3310500500ecf2e
git.kernel.org/stable/c/af32dbb2ca... WEB
https://git.kernel.org/stable/c/af32dbb2ca0b3d09271ab718d13857a457fa16f2
git.kernel.org/stable/c/e835bf9a05... WEB
https://git.kernel.org/stable/c/e835bf9a055f71874065a40780ca5560b7df8b33

Frequently Asked Questions

What is CVE-2026-63895?
CVE-2026-63895 is a security vulnerability in Software classified as a security vulnerability vulnerability under General Security Weakness.
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-63895?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What CWE is associated with CVE-2026-63895?
CVE-2026-63895 is classified under General Security Weakness.
How can I check Maven dependencies for CVE-2026-63895?
Run the dependency tree command: 'mvn dependency:tree'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-hqp4-gw43-6pcc",
  "modified" : "2026-07-19T18:31:44Z",
  "published" : "2026-07-19T18:31:44Z",
  "aliases" : [ "CVE-2026-63895" ],
  "details" : "In the Linux kernel, the following vulnerability has been resolved:\n\nusb: gadget: f_fs: copy only received bytes on short ep0 read\n\nffs_ep0_read() allocates its control-OUT data buffer with\nkmalloc() (not kzalloc) at the Length value from the Setup\npacket, then copies that full len to userspace regardless of\nhow many bytes were actually received:\n\n    data = kmalloc(len, GFP_KERNEL);\n    ...\n    ret = __ffs_ep0_queue_wait(ffs, data, len);\n    if ((ret > 0) && (copy_to_user(buf, data, len)))\n            ret = -EFAULT;\n\n__ffs_ep0_queue_wait() returns req->actual, which on a short\ncontrol OUT transfer is strictly less than len.  The\ncopy_to_user() call still copies len bytes, so on a short OUT\nthe last (len - ret) bytes of the kmalloc() buffer --\nuninitialised slab residue -- are delivered to the FunctionFS\ndaemon.\n\nShort ep0 OUT completions are specified USB control-transfer\nbehavior and are produced by in-tree UDCs:\n\n  * dwc2 continues on req->actual < req->length for ep0 DATA OUT\n    (short-not-ok is the only ep0-OUT stall path).\n  * aspeed_udc ends ep0 OUT on rx_len < ep->ep.maxpacket.\n  * renesas_usbf logs \"ep0 short packet\" and completes the\n    request.\n  * dwc3 stalls on short IN but not on short OUT.\n\nA short ep0 OUT is therefore not evidence of a broken UDC; it is\na normal condition f_fs has to cope with.  The sibling gadgetfs\nimplementation in drivers/usb/gadget/legacy/inode.c already does\nthis correctly via min(len, dev->req->actual) before\ncopy_to_user().  This patch brings f_fs.c to the same safe\npattern rather than trimming at a defensive layer.\n\nThe bug is reached from the FunctionFS device node, which in\nreal deployments is owned by the privileged gadget daemon\n(adbd, UMS, composite gadget services, etc.); it is not\nreachable from unprivileged userspace.  Linux host stacks\nnormally reject short-wLength control OUTs before they reach\nthe gadget, so reproducing this required a build that\nbypasses that host-side check.  With the bypass in place, a\n1-byte payload on a 64-byte Setup produces 63 bytes of\nnon-canary slab residue in the daemon's read buffer.\n\nFix by copying only ret (actually received) bytes to\nuserspace.",
  "severity" : [ ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-63895"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/23c1f7deb9dd8447ecde749850676302aa1e2bd3"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/4e036c10e7f4df5d951c69cc3697bc8e209c6d02"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/607730a414773a7cbe3037a64a6c64e72689ff5e"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/88874a19b2b093bfaaa1c0090fa536c44da8c08b"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/90ccf5fb63243fae1b4b3200f3310500500ecf2e"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/af32dbb2ca0b3d09271ab718d13857a457fa16f2"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/e835bf9a055f71874065a40780ca5560b7df8b33"
  } ],
  "database_specific" : {
    "cwe_ids" : [ ],
    "severity" : null,
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-07-19T16:17:06Z"
  }
}