CVE-2021-38209: linux linux_kernel Observable Discrepancy
CVSS: 3.3v3.1LowModified
AliasesUBUNTU-CVE-2021-38209DEBIAN-CVE-2021-38209
Published 08-08-2021Last modified 04-08-2024
Vulnerability summary
CVE-2021-38209 is a low (CVSS 3.3) Observable Discrepancy vulnerability in linux linux_kernel. EPSS estimates a 0.28% chance of exploitation in the next 30 days, higher than 19.7% of scored vulnerabilities.
CVSS score
3.3/10
010
Low · v3.1 (NVD)EPSS score
0.28%
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 5 · Related 5Timeline
- 08-08-2021PublishedVulnerability first disclosed.
- 04-08-2024Last modifiedVulnerability information updated.
Description
net/netfilter/nf_conntrack_standalone.c in the Linux kernel before 5.12.2 allows observation of changes in any net namespace because these changes are leaked into all other net namespaces. This is related to the NF_SYSCTL_CT_MAX, NF_SYSCTL_CT_EXPECT_MAX, and NF_SYSCTL_CT_BUCKETS sysctls.
CVSS metrics
4 scores · 3 sources · 2 versionsLow 3.3Preferred score · NVD (NIST)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:NSourcesAll 3 agree
- OSV · UbuntuEcosystem advisory · calculated3.3LowCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
- OSV · DebianEcosystem advisory · calculated3.3LowCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Low 2.1Preferred score · NVD (NIST)
AV:L/AC:L/Au:N/C:P/I:N/A:NSourcesSingle source
EPSS trend
Probability
0.28%
Chance of exploitation in the next 30 days
Percentile
20%
Versus all other CVEs
30-day change
0.00 pp
From 0.28% on 21-09-2026
21-09-202621-10-2026
EPSS score0.28%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Ubuntu25 products
- linux-aws-5.0All versions (No fix recorded)
- linux-aws-5.3All versions (No fix recorded)
- linux-aws-5.8All versions (No fix recorded)
- linux-azureAll versions (No fix recorded)
- linux-azure-5.3All versions (No fix recorded)
Debian1 product
- linux< 5.10.38-1
Linux1 product
- linux_kernel< 5.12.2
3 vendors · 27 products
References
6 links- github.com/torvalds/linux/commit/2671fa4dc0109d3fb581bc3078fdf17b5d9080f6X Refsource MISCREPORTPatchThird Party Advisory
- cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.12.2X Refsource MISCREPORTMailing ListPatchVendor Advisory
