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NVD / CVE Program· CNA Linux

CVE-2021-47509: ALSA: pcm: oss: Limit the period size to 16MB

MediumCVSS 5.5 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 22/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.24% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 2e54cf6794bf82a54aaefc78da13819aea9cd28a, 35a3e511032146941085f87dd9fb5b82ea5c00a2, 76f19e4cbb548e28547f8c328aa0bfb3a10222d3.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 2e54cf6794bf82a54aaefc78da13819aea9cd28a, 35a3e511032146941085f87dd9fb5b82ea5c00a2, 76f19e4cbb548e28547f8c328aa0bfb3a10222d3 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: ALSA: pcm: oss: Limit the period size to 16MB Set the practical limit to the period size (the fragment shift in OSS) instead of a full 31bit; a too large value could lead to the exhaust of memory as we allocate temporary buffers of the period size, too. As of this patch, we set to 16MB limit, which should cover all use cases.

Published
May 24, 2024
Updated
Jun 17, 2026
EPSS
0.2% · 15th percentile
CWE
—

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2021-47509

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
linuxlinux kernel

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 2.6.12affected
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before d1bb703ad050de9095f10b2d3416c32921ac6bccaffected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before b02a41eebcc36d4f07196780f2e165ca2c499257affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before be55f306396cd62c6889286a7194fd8b53363aebaffected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 2e54cf6794bf82a54aaefc78da13819aea9cd28aaffected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 76f19e4cbb548e28547f8c328aa0bfb3a10222d3affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before ad45babf7886e7a212ee1d5eda9ef49f696db43caffected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 35a3e511032146941085f87dd9fb5b82ea5c00a2affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 8839c8c0f77ab8fc0463f4ab8b37fca3f70677c2affected · git
    • before 2.6.12not affected · semver
Affected versions · NVD (8)

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernelbefore 4.4.295
  • linux linux kernel4.5 and later · before 4.9.293
  • linux linux kernel4.10 and later · before 4.14.258
  • linux linux kernel4.15 and later · before 4.19.221
  • linux linux kernel4.20 and later · before 5.4.165
  • linux linux kernel5.5 and later · before 5.10.85
  • linux linux kernel5.11 and later · before 5.15.8
  • linux linux kernel5.16

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 5.15.15-15.15.15-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe…KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2021-47507May 24, 2024 · nfsd: Fix nsfd startup race (again)
    18Monitor
  • ← EarlierCVE-2021-47508May 24, 2024 · btrfs: free exchange changeset on failures
    22Monitor
  • Later →CVE-2021-47510May 24, 2024 · btrfs: fix re-dirty process of tree-log nodes
    22Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux2e54cf6794bf82a54aaefc78da13819aea9cd28aVendor (CNA)
Linux Linux35a3e511032146941085f87dd9fb5b82ea5c00a2Vendor (CNA)
Linux Linux76f19e4cbb548e28547f8c328aa0bfb3a10222d3Vendor (CNA)
Linux Linux8839c8c0f77ab8fc0463f4ab8b37fca3f70677c2Vendor (CNA)
Linux Linuxad45babf7886e7a212ee1d5eda9ef49f696db43cVendor (CNA)
Linux Linuxb02a41eebcc36d4f07196780f2e165ca2c499257Vendor (CNA)
Linux Linuxbe55f306396cd62c6889286a7194fd8b53363aebVendor (CNA)
Linux Linuxd1bb703ad050de9095f10b2d3416c32921ac6bccVendor (CNA)
debian:linux5.15.15-1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

—

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

References

Show all references (7 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records