5.5

CVE-2021-34556: debian debian_linux Observable Discrepancy

Modified
AliasesUBUNTU-CVE-2021-34556DEBIAN-CVE-2021-34556
Published 02-08-2021Last modified 08-10-2026

Vulnerability summary

CVE-2021-34556 is a medium (CVSS 5.5) Observable Discrepancy vulnerability in debian debian_linux. EPSS estimates a 0.42% chance of exploitation in the next 30 days, higher than 36.3% of scored vulnerabilities.

Priority
Routine

Not severe (CVSS 5.5, local access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
5.5/10
010
Medium · v3.1 (NVD)
EPSS score
0.42%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 31 · Related 28
DLA-2785-1MGASA-2021-0397MGASA-2021-0398OPENSUSE-SU-2021:1271-1OPENSUSE-SU-2021:1477-1OPENSUSE-SU-2021:3179-1

Timeline

  1. 02-08-2021
    PublishedVulnerability first disclosed.
  2. 08-10-2026
    Last modifiedVulnerability information updated.

Description

In the Linux kernel through 5.13.7, an unprivileged BPF program can obtain sensitive information from kernel memory via a Speculative Store Bypass side-channel attack because the protection mechanism neglects the possibility of uninitialized memory locations on the BPF stack.

CVSS metrics

4 scores · 3 sources · 2 versions

EPSS trend

Probability

0.42%

Chance of exploitation in the next 30 days

Percentile

36%

Versus all other CVEs

30-day change

No change 0.00 pp

From 0.42% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.

Ubuntu60 products
  • linuxAll versions (No fix recorded) | < 5.4.0-90.101
  • linux-awsAll versions (No fix recorded) | < 5.4.0-1059.62
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11< 5.11.0-1019.20~20.04.1
  • linux-aws-5.3All versions (No fix recorded)
Debian2 products
Fedoraproject1 product
Linux1 product

4 vendors · 64 products

References

17 links
Show all 17 references