CVE-2026-64327: usb: gadget: f_fs: Initialize epfile->in early to fix endpoint direction checks
Vulnerability summary
CVE-2026-64327 is a medium (CVSS 5.5) vulnerability in linux. EPSS estimates a 0.16% chance of exploitation in the next 30 days, higher than 5.1% of scored vulnerabilities.
Not severe (CVSS 5.5, local access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 17 · Related 17Timeline
- 25-07-2026PublishedVulnerability first disclosed.
- 17-08-2026Last modifiedVulnerability information updated.
Description
In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_fs: Initialize epfile->in early to fix endpoint direction checks When parsing endpoint descriptors, ffs_data_got_descs() generates the eps_addrmap which contains the endpoint direction. However, epfile->in was previously only populated in ffs_func_eps_enable() which executes upon USB host connection. As a result, early userspace ioctls like FUNCTIONFS_DMABUF_ATTACH that run before the host connects would see epfile->in as 0, leading to incorrect DMA directions. By moving the initialization to ffs_epfiles_create(), epfile->in is accurate before userspace opens the endpoint files.
CVSS metrics
3 scores · 3 sources · 1 version- OSV · UbuntuEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- OSV · DebianEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
0.16%
Chance of exploitation in the next 30 days
Percentile
5%
Versus all other CVEs
30-day change
No change 0.00 pp
From 0.16% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeNo weakness data has been published for this record.
Affected systems
Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.
Ubuntu119 products
- linux< 7.0.0-31.31
- linux-allwinner-5.19All versions (No fix recorded)
- linux-aws< 7.0.0-1012.12
- linux-aws-5.0All versions (No fix recorded)
- linux-aws-5.11All versions (No fix recorded)
Debian2 products
- linux< 6.12.96-1 | < 7.1.4-1
- linux-6.12< 6.12.100-1~deb12u1
Linux2 products
- linux≥ 7b07a2a7ca02a20124b552be96c5a56910795488, < 82cf1142e5ccf2b6d6d22ef713aaf3e5f2b5716b | ≥ 7b07a2a7ca02a20124b552be96c5a56910795488, < 9e04055ab5fc0470a0031ee6934739f9aa8f34a5 | ≥ 7b07a2a7ca02a20124b552be96c5a56910795488, < f99f32ea9aa976afcbec20647ed33b50a52002c1 | ≥ 7b07a2a7ca02a20124b552be96c5a56910795488, < 82cfd4739011bdc7e87b5d585703427e89ddfaa5 | 6.9
- linux_kernel≥ 6.9, < 6.12.96 | ≥ 6.13, < 6.18.39 | ≥ 6.19, < 7.1.4 | 7.2:rc1 | 7.2:rc2
3 vendors · 123 products
