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CVE-2026-120308— Beta9 host filesystem exposure via volume path traversal

Quick assessment

Affected
beam-cloud Beta9 gateway
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Beta9 租户在部署函数、端点或任务队列时，可以挂载卷。网关通过将共享卷根目录、工作区名称以及存根配置中的卷标识符拼接，构建主机路径。然而，系统并未验证该标识符是否指向该工作区所拥有的卷。若标识符中包含父目录路径段（如 ），拼接后的路径会被回退至工作进程的文件系统根目录，导致工作进程将该路径以读写模式绑定挂载到沙箱中（除非该卷被显式标记为只读）。因此，拥有工作区令牌的租户可读取和写入工作进程的文件，包括存储在同一机器上的其他租户的卷。 该漏洞已在网关 0.1.769 和工作进程 0.1.745 版本中确认存在。修

CVSS 9.9 · Critical

Affected Version Matrix 2

VendorProduct Version RangeStatus
beam-cloud Beta9 gateway < 0.1.776 affected
beam-cloud Beta9 worker < 0.1.756 affected
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I. Basic Information for CVE-2026-120308

Vulnerability Information
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Vulnerability Title
Beta9 host filesystem exposure via volume path traversal
Source: CVE Program / CVE List V5
Vulnerability Description
A Beta9 tenant can attach a volume when deploying a function, endpoint, or task queue. The gateway builds the host path by joining the shared volumes root, the workspace name, and the volume identifier from the stub configuration. Nothing checks that the identifier names a volume that workspace owns. Parent-directory segments in the identifier collapse the joined path to the worker's filesystem root, and the worker bind-mounts that path into the sandbox read-write unless the volume was explicitly marked read-only. A tenant with a workspace token can therefore read and write the worker's files, including other tenants' volumes stored on that machine. Confirmed against gateway 0.1.769 and worker 0.1.745. Fixed in gateway 0.1.776 and worker 0.1.756: volume identifiers and mount paths are validated before a mount is built, including for stubs saved before the check existed, and the gateway rejects a volume that does not exist or is not owned by the workspace.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
对路径名的限制不恰当(路径遍历)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
beam-cloud Beta9 gateway 0 ~ 0.1.776 -
beam-cloud Beta9 worker 0 ~ 0.1.756 -

II. Public POCs for CVE-2026-120308

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III. Intelligence Information for CVE-2026-120308

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Other References for CVE-2026-120308 (7)

Same Patch Batch · beam-cloud · 2026-11-01 · 3 CVEs total

CVE-2026-120306 9.9 CRITICAL Beta9 build sandbox escape via chroot-only isolation
CVE-2026-120307 9.9 CRITICAL Beta9 container escape via unvalidated sandbox file paths

IV. Related Vulnerabilities

Same vendor: beam-cloud
Same weakness: CWE-22