CVE-2026-64331: usbip: vudc: fix NULL deref in vep_dequeue()
Vulnerability summary
CVE-2026-64331 is a medium (CVSS 5.5) NULL Pointer Dereference vulnerability in linux. EPSS estimates a 0.12% chance of exploitation in the next 30 days, higher than 2% 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 31 · Related 31Timeline
- 25-07-2026PublishedVulnerability first disclosed.
- 17-08-2026Last modifiedVulnerability information updated.
Description
In the Linux kernel, the following vulnerability has been resolved: usbip: vudc: fix NULL deref in vep_dequeue() vep_alloc_request() wasn't initializing vrequest->udc, so cancellations on the FunctionFS AIO path were arriving in vep_dequeue without a valid UDC reference. Since vrequest->udc is never actually properly used anywhere, we opt to remove it, and update vep_dequeue to obtain a reference to the udc with ep_to_vudc(), consistent with the other vep_ ops. AFAICT this bug has existed for ~10 years. Seems that nobody has really stressed the FunctionFS AIO path on usbip's vudc. I tested this fix in a QEMU aarch64 guest driving FunctionFS endpoints via AIO. Before the fix, running `usbip attach` from the host would cause the guest to oops with the following backtrace: Call trace: vep_dequeue+0x1c/0xe4 (P) usb_ep_dequeue+0x14/0x20 ffs_aio_cancel+0x24/0x34 __arm64_sys_io_cancel+0xb0/0x124 do_el0_svc+0x68/0x100 el0_svc+0x18/0x5c el0t_64_sync_handler+0x98/0xdc el0t_64_sync+0x154/0x158
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
0.12%
Chance of exploitation in the next 30 days
Percentile
2%
Versus all other CVEs
30-day change
No change 0.00 pp
From 0.12% 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 causeAffected systems
Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.
Ubuntu168 products
- linuxAll versions (No fix recorded) | < 5.15.0-198.208 | < 6.8.0-147.147 | < 7.0.0-31.31
- linux-allwinner-5.19All versions (No fix recorded)
- linux-awsAll versions (No fix recorded) | < 5.15.0-1117.124 | < 6.8.0-1067.70 | < 7.0.0-1012.12
- linux-aws-5.0All versions (No fix recorded)
- linux-aws-5.11All versions (No fix recorded)
Debian2 products
- linux< 6.1.180-1 | < 6.12.96-1 | < 7.1.4-1
- linux-6.12< 6.12.100-1~deb12u1
Linux2 products
- linux≥ b6a0ca11186759ad7045d68a5447b1e89f658384, < 9858c91d9ee6a13c45311569039413729fc9b757 | ≥ b6a0ca11186759ad7045d68a5447b1e89f658384, < 1226293ec9bed3d4cc5b05eeeb811d315ca51652 | ≥ b6a0ca11186759ad7045d68a5447b1e89f658384, < 3750f75f29f99c0223601e2ee73ad084adec47bd | ≥ b6a0ca11186759ad7045d68a5447b1e89f658384, < d0ebf9cc7c2ddf95a7cfc654b940bdacb7edde97 | ≥ b6a0ca11186759ad7045d68a5447b1e89f658384, < 0025276175fbbe0dcbf3f84d090b0adee769e9d9 | ≥ b6a0ca11186759ad7045d68a5447b1e89f658384, < 347b59e9f96719d89b6ef555d02a18ada1a5846f | ≥ b6a0ca11186759ad7045d68a5447b1e89f658384, < 0443e4416aa1ee97748d1ed904eaf3352c60045e | ≥ b6a0ca11186759ad7045d68a5447b1e89f658384, < c5371e0b91b24159a3ebaa61e70b0980bcf03c0a | 4.7
- linux_kernel≥ 4.7, < 5.10.261 | ≥ 5.11, < 5.15.212 | ≥ 5.16, < 6.1.178 | ≥ 6.2, < 6.6.145 | ≥ 6.7, < 6.12.96 | ≥ 6.13, < 6.18.39 | ≥ 6.19, < 7.1.4 | 7.2:rc1 | 7.2:rc2
3 vendors · 172 products
