Out-of-bounds Read in FreeBSD Libfetch
CVE-2021-36159
libfetch before 2021-07-26, as used in apk-tools, xbps, and other products, mishandles numeric strings for the FTP and HTTP protocols. The FTP passive mode implementation allows an out-of-bounds read because strtol is used to parse the relevant numbers into address bytes. It does not check if the line ends prematurely. If it does, the for-loop condition checks for the '\0' terminator one byte too late.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H.
EPSS exploit prediction
EPSS: 0.026 (85.0th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 85th percentile — 85.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.026 · newest: 0.026 · change: 0.000
Affected products
Weakness classification (CWE)
Public proof-of-concept exploits
References
- gitlab.alpinelinux.org/alpine/apk-tools/-/issues/10749 (Exploit, Third Party Advisory)
- github.com/freebsd/freebsd-src/commits/main/lib/libfetch (Patch, Third Party Advisory)
- lists.apache.org/thread.html/r61db8e7dcb56dc000a5387a88f7a473bacec5ee01b9ff3f55… (mailing-list)
- lists.apache.org/thread.html/r61db8e7dcb56dc000a5387a88f7a473bacec5ee01b9ff3f55… (mailing-list)
- lists.apache.org/thread.html/rbf4ce74b0d1fa9810dec50ba3ace0caeea677af7c27a97111… (mailing-list)
- lists.apache.org/thread.html/rbf4ce74b0d1fa9810dec50ba3ace0caeea677af7c27a97111… (mailing-list)
Frequently asked questions
- What is CVE-2021-36159?
- CVE-2021-36159 is a critical-severity vulnerability in FreeBSD Libfetch, classified under Out-of-bounds Read. CVSS score: 9.1/10. Published 2021-08-03.
- How severe is CVE-2021-36159?
- Critical severity. CVSS v3 base score is 9.1 out of 10.
- Is CVE-2021-36159 known to be exploited?
- 19 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.