Predictive Vulnerability Intelligence.

Product

  • Product
  • Pricing
  • Documentation

Company

  • About
  • Partnerships
  • Blog
  • Support

Legal

  • Terms
  • Privacy
  • Data Licensing

© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2021-36159

29
FAUCET Score

CVE-2021-36159 is a critical vulnerability affecting libfetch versions prior to 2021-07-26, impacting products like apk-tools and xbps. It involves an out-of-bounds read in the FTP passive mode implementation due to improper handling of numeric strings, specifically when strtol parses address bytes without validating premature line termination. With a CVSS score of 9.1, this vulnerability is network-exploitable with low attack complexity, requiring no user interaction or privileges, and can lead to high confidentiality and availability impacts. Currently, there is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
< 2021-07-26CPE matchmatch criteria
cpe:2.3:a:freebsd:libfetch:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.1CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.2
CvssVersion
3.1

Exploit Intelligence

EPSS Score
2.64%
Probability of exploitation in next 30 days
EPSS Percentile
84.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0264 is in the 74th percentile among its peer group of 36,897 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (1)

github_advisorypatch availablevia nvd_reference
View patch

Vendor Advisories (1)

redhatCVE-2021-36159Important

libfetch: an out of boundary read while libfetch uses strtol to parse the relevant numbers into address bytes leads to information leak or crash

Aug 3, 2021

References

github.com / freebsd/freebsd-src/commits/main/lib/libfetch
PatchThird Party Advisory
gitlab.alpinelinux.org / alpine/apk-tools/-/issues/10749
ExploitThird Party Advisory
lists.apache.org / thread.html/r61db8e7dcb56dc000a5387a88f7a473bacec5ee01b9ff3f55308aacc%40%3Cdev.kafka.apache.org%3E
lists.apache.org / thread.html/r61db8e7dcb56dc000a5387a88f7a473bacec5ee01b9ff3f55308aacc%40%3Cusers.kafka.apache.org%3E
lists.apache.org / thread.html/rbf4ce74b0d1fa9810dec50ba3ace0caeea677af7c27a97111c06ccb7%40%3Cdev.kafka.apache.org%3E
lists.apache.org / thread.html/rbf4ce74b0d1fa9810dec50ba3ace0caeea677af7c27a97111c06ccb7%40%3Cusers.kafka.apache.org%3E