CVE-2021-30481
Valve Steam before 2021-04-17, when a Source engine game is installed, allows remote authenticated users to execute arbitrary code because of a buffer overflow that occurs for a Steam invite after one click.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (3.50%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
Valve Steam before 2021-04-17, when a Source engine game is installed, allows remote authenticated users to execute arbitrary code because of a buffer overflow that occurs for a Steam invite after one click.
- CVSS 3.1
- 9.0 CRITICALCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H
- EPSS
- 3.50% probability · 89th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-120
- Affected
- valvesoftware/steam client
- Source
- cve@mitre.org
EPSS 3.5% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://news.ycombinator.com/item?id=26762170Issue Tracking, Third Party Advisory
- https://twitter.com/floesen_/status/1337107178096881666Third Party Advisory
- https://twitter.com/the_secret_club/status/1380868759129296900Exploit, Third Party Advisory
- https://www.youtube.com/watch?v=rNQn--9xR1QExploit, Third Party Advisory
- https://news.ycombinator.com/item?id=26762170Issue Tracking, Third Party Advisory
- https://twitter.com/floesen_/status/1337107178096881666Third Party Advisory
- https://twitter.com/the_secret_club/status/1380868759129296900Exploit, Third Party Advisory
- https://www.youtube.com/watch?v=rNQn--9xR1QExploit, Third Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.