CVE-2021-42386: busybox Use After Free
CVSS: 7.2v3.1HighModified
AliasesALPINE-CVE-2021-42386UBUNTU-CVE-2021-42386DEBIAN-CVE-2021-42386
Published 15-11-2021Last modified 03-11-2025
Vulnerability summary
CVE-2021-42386 is a high (CVSS 7.2) Use After Free vulnerability in busybox. EPSS estimates a 2.73% chance of exploitation in the next 30 days, higher than 85.8% of scored vulnerabilities.
CVSS score
7.2/10
010
High · v3.1 (CVE.org)EPSS score
2.73%
0%100%
Low · 0.00 pp in 30 daysKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded
Advisory lineage
Upstream 0 · Downstream 8 · Related 6Timeline
- 15-11-2021PublishedVulnerability first disclosed.
- 03-11-2025Last modifiedVulnerability information updated.
Description
A use-after-free in Busybox's awk applet leads to denial of service and possibly code execution when processing a crafted awk pattern in the nvalloc function
CVSS metrics
6 scores · 5 sources · 2 versionsHigh 7.2Preferred score · CVE.org (CNA)
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:HSourcesAll 5 agree
- OSV · AlpineEcosystem advisory · calculated7.2HighCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
- OSV · UbuntuEcosystem advisory · calculated7.2HighCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
- OSV · DebianEcosystem advisory · calculated7.2HighCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
- NVDNIST7.2HighCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
Medium 6.5Preferred score · NVD (NIST)
AV:N/AC:L/Au:S/C:P/I:P/A:PSourcesSingle source
EPSS trend
Probability
2.73%
Chance of exploitation in the next 30 days
Percentile
86%
Versus all other CVEs
30-day change
0.00 pp
From 2.73% on 18-09-2026
18-09-202618-10-2026
EPSS score2.73%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Alpine1 product
- busybox≥ 1.16.0, < 1.31.1-r11 | ≥ 1.16.0, < 1.31.1-r21 | ≥ 1.16.0, < 1.32.1-r7 | ≥ 1.16.0, < 1.33.1-r6 | ≥ 1.16.0, < 1.34.0-r0
Busybox1 product
- busybox≥ unspecified, < 1.34.0 | ≥ 1.16.0, ≤ 1.33.1
Debian1 product
- busybox< 1:1.35.0-1
Fedoraproject1 product
- fedoraEOL33 | 34
Ubuntu1 product
- busyboxAll versions (No fix recorded) | < 1:1.27.2-2ubuntu3.4 | < 1:1.30.1-4ubuntu6.4 | < 1:1.30.1-7ubuntu2
5 vendors · 5 products
References
12 links- jfrog.com/blog/unboxing-busybox-14-new-vulnerabilities-uncovered-by-claroty-and-jfrog/REPORTThird Party Advisory
- lists.fedoraproject.org/archives/…Vendor Advisory
- lists.fedoraproject.org/archives/…Vendor Advisory
- security.netapp.com/advisory/ntap-20211223-0002/Third Party Advisory
