CVE-2021-4135: linux linux_kernel
Vulnerability summary
CVE-2021-4135 is a medium (CVSS 5.5) vulnerability in linux linux_kernel. EPSS estimates a 0.23% chance of exploitation in the next 30 days, higher than 14% of scored vulnerabilities.
Not severe (CVSS 5.5, local access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 21 · Related 17Timeline
- 14-07-2022PublishedVulnerability first disclosed.
- 08-10-2026Last modifiedVulnerability information updated.
Description
A memory leak vulnerability was found in the Linux kernel's eBPF for the Simulated networking device driver in the way user uses BPF for the device such that function nsim_map_alloc_elem being called. A local user could use this flaw to get unauthorized access to some data.
CVSS metrics
3 scores · 3 sources · 1 version- OSV · UbuntuEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
- OSV · DebianEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
EPSS trend
Probability
0.23%
Chance of exploitation in the next 30 days
Percentile
14%
Versus all other CVEs
30-day change
No change 0.00 pp
From 0.23% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-200Exposure of Sensitive Information to an Unauthorized ActorThe product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.
- CWE-401Missing Release of Memory after Effective LifetimeThe product does not sufficiently track and release allocated memory after it has been used, making the memory unavailable for reallocation and reuse.
Affected systems
Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.
Ubuntu62 products
- linux< 5.4.0-105.119
- linux-aws< 5.4.0-1069.73
- linux-aws-5.0All versions (No fix recorded)
- linux-aws-5.11All versions (No fix recorded)
- linux-aws-5.13< 5.13.0-1019.21~20.04.1
Debian1 product
- linux< 5.15.15-1
Linux1 product
- linux_kernelEOL< 5.16 | 5.16 | 5.16:rc1 | 5.16:rc2 | 5.16:rc3 | 5.16:rc4 | 5.16:rc5
3 vendors · 64 products
References
11 links- git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git/commit/?id=481221775d53X Refsource MISCMailing ListPatchVendor Advisory
