Insecure temporary file in Netflix OSS Hollow

published 2021-03-23 5 y ago modified 2026-06-17 4 mo ago also GHSA-9295-mhf3-v33m , EUVD-2021-0635

cvss: 4.4; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 0.3%; EPSS 0.3% chance of exploitation in 30 days, percentile 16%
public exploits: 0; none known

In Netflix OSS Hollow, since the Files.exists(parent) is run before creating the directories, an attacker can pre-create these directories with wide permissions. Additionally, since an insecure source of randomness is used, the file names to be created can be deterministically calculated.

Exploit prediction

0.25% chance of exploitation in the next 30 days, higher than 16% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
NVD	3.1	4.4	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
NVD	2.0	3.6	AV:L/AC:L/Au:N/C:P/I:P/A:N
GitHub	3.1	4.4	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

Affected packages

ecosystem	package	affected	fixed in
maven	com.netflix.hollow:hollow	<=6.1.0	no fix listed

Affected products

n/a Netflix OSS Hollow

Classification

Weakness

CWE-330 Use of Insufficiently Random Values
CWE-377 DEPRECATED: Insecure Temporary File

References

github.com /Netflix/security-bulletins/blob/master/advisories/nflx-2021-001.md
web, third-party-advisory
github.com /JLLeitschuh/security-research/security/advisories/GHSA-j83w-7qr9-wv86
web
nvd.nist.gov /vuln/detail/CVE-2021-28099
advisory
github.com /Netflix/hollow/issues/502
web

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary