CVE-2021-47509: ALSA: pcm: oss: Limit the period size to 16MB
Vulnerability summary
CVE-2021-47509 is a medium (CVSS 5.5) vulnerability in linux. EPSS estimates a 0.24% chance of exploitation in the next 30 days, higher than 15.1% 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 10 · Related 10Timeline
- 24-05-2024PublishedVulnerability first disclosed.
- 11-05-2026Last modifiedVulnerability information updated.
Description
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.
CVSS metrics
5 scores · 4 sources · 2 versions- OSV · UbuntuEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- OSV · DebianEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- NVDNIST5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
0.24%
Chance of exploitation in the next 30 days
Percentile
15%
Versus all other CVEs
30-day change
No change 0.00 pp
From 0.24% 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 causeNo weakness data has been published for this record.
Affected systems
Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.
Ubuntu89 products
- linuxAll versions (No fix recorded) | < 4.15.0-169.177 | < 5.4.0-100.113
- linux-allwinner-5.19All versions (No fix recorded)
- linux-awsAll versions (No fix recorded) | < 4.15.0-1121.129 | < 5.4.0-1066.69
- linux-aws-5.0All versions (No fix recorded)
- linux-aws-5.11All versions (No fix recorded)
Linux2 products
- linux≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < d1bb703ad050de9095f10b2d3416c32921ac6bcc | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < b02a41eebcc36d4f07196780f2e165ca2c499257 | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < be55f306396cd62c6889286a7194fd8b53363aeb | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 2e54cf6794bf82a54aaefc78da13819aea9cd28a | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 76f19e4cbb548e28547f8c328aa0bfb3a10222d3 | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < ad45babf7886e7a212ee1d5eda9ef49f696db43c | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 35a3e511032146941085f87dd9fb5b82ea5c00a2 | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 8839c8c0f77ab8fc0463f4ab8b37fca3f70677c2 | 2.6.12
- linux_kernel< 4.4.295 | ≥ 4.5, < 4.9.293 | ≥ 4.10, < 4.14.258 | ≥ 4.15, < 4.19.221 | ≥ 4.20, < 5.4.165 | ≥ 5.5, < 5.10.85 | ≥ 5.11, < 5.15.8 | 5.16:rc1 | 5.16:rc2 | 5.16:rc3 | 5.16:rc4
Debian1 product
- linux< 5.15.15-1
3 vendors · 92 products
