CVE-2026-39461
📛 CVE Title
select(2) file descriptor set overflow causes stack overflow
Description
libcasper(3) communicates with helper processes via UNIX domain sockets, and uses the select(2) system call to wait for data to become available. However, it does not verify that its socket descriptor fits within select(2)'s descriptor set size limit of FD_SETSIZE (1024). An attacker able to cause an application using libcasper(3) to allocate large file descriptors, e.g., by opening many descriptors and executing a program which is not careful to close them upon startup, may trigger stack corruption. If the target application runs with setuid root privileges, this could be used to escalate local privileges.
Overview
- State
- PUBLISHED
- Assigner (CNA)
- freebsd
- CVSS severity
- high
- CVSS score
- 8.8 / 10
- CVSS vector
AV:L/AC:L/Au:S/C:C/I:C/A:C- Effective score
- 8.8 / 10 HIGH source: CNA overview
- CWE(s)
-
CWE-121 - Reserved
- 2026-04-28
- Published
- 2026-05-21 09:20 UTC
- Last updated
- 2026-05-21 09:20 UTC
- Source
- https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/39xxx/CVE-2026-39461.json
- Linked Threat
- CVE-2026-39461 — CVE-2026-39461
NVD triage scoring NVD CVE 2.0
Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.
- NVD published
- 2026-05-21 10:16:25 UTC
- NVD last modified
- 2026-05-21 19:01:35 UTC
- NVD CVSS v3.1
- 8.8 / 10 HIGH source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
- NVD CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H- Exploitability subscore
- 2.0 / 10
- Impact subscore
- 6.0 / 10
- EPSS score
- 0.0001 (probability of exploitation in next 30 days)
- EPSS percentile
- 0.34% vs all CVEs — higher = more likely to be exploited, as of 2026-05-24
NVD / KEV / EPSS data refreshed 2026-05-25 00:30 UTC. Re-run the 🛰 Backfill from NVD button above to refresh.
European Union Vulnerability Database ENISA EUVD
ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.
- EUVD ID
-
EUVD-2026-31258 - Assigner
- freebsd
- Published
- May 21, 2026, 9:20:26 AM
- Updated
- May 22, 2026, 3:55:38 AM
- EUVD base score (CVSS 3.1)
-
8.8 / 10
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H - EUVD-reported EPSS
- 0.0100
- Vendors
- FreeBSD
- Products
-
FreeBSD (15.0-RELEASE <p9)FreeBSD (14.3-RELEASE <p14)FreeBSD (14.4-RELEASE <p5)
- Aliases
-
GHSA-pwph-948j-pgvj
ENISA description: libcasper(3) communicates with helper processes via UNIX domain sockets, and uses the select(2) system call to wait for data to become available. However, it does not verify that its socket descriptor fits within select(2)'s descriptor set size limit of FD_SETSIZE (1024). An attacker able to cause an application using libcasper(3) to allocate large file descriptors, e.g., by opening many descriptors and executing a program which is not careful to close them upon startup, may trigger stack corruption. If the target application runs with setuid root privileges, this could be used to escalate local privileges.
EUVD references (1)
Affected products (1)
| Vendor | Product | Versions | Platforms |
|---|---|---|---|
| FreeBSD | FreeBSD |
15.0-RELEASE (affected),
14.4-RELEASE (affected),
14.3-RELEASE (affected)
|
— |
Affected products — CPE 2.3 (29) NVD
NVD's normalized CPE 2.3 matchers, used by vendor tools (vulnerability scanners, asset managers) for automated detection. Compare with the CNA's free-text "Affected products" section above.
cpe:2.3:o:freebsd:freebsd:14.3:-:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:14.3:p1:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:14.3:p10:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:14.3:p11:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:14.3:p12:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:14.3:p13:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:14.3:p2:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:14.3:p3:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:14.3:p4:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:14.3:p5:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:14.3:p6:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:14.3:p7:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:14.3:p8:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:14.3:p9:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:14.4:-:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:14.4:p1:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:14.4:p2:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:14.4:p3:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:14.4:p4:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:14.4:rc1:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:15.0:-:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:15.0:p1:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:15.0:p2:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:15.0:p3:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:15.0:p4:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:15.0:p5:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:15.0:p6:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:15.0:p7:*:*:*:*:*:*cpe:2.3:o:freebsd:freebsd:15.0:p8:*:*:*:*:*:*
Vendor references (1)
References embedded in the original CVE record by the assigning CNA.
Web references (5)
DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.
- https://nvd.nist.gov/vuln/detail/CVE-2026-39461 tenable:nvd.nist.gov
- https://security.freebsd.org/advisories/FreeBSD-SA-26:22.libcasper.asc tenable:security.freebsd.org
- https://www.first.org/epss/ tenable:www.first.org
- https://attackerkb.com/topics/CVE-2026-39461 rapid7:attackerkb.com
- https://www.cve.org/CVERecord?id=CVE-2026-39461 rapid7:www.cve.org
NVD-tagged references (1)
Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.
- https://security.freebsd.org/advisories/FreeBSD-SA-26:22.libcasper.asc secteam@freebsd.org Vendor Advisory
Remediations (19)
Remediations are stored against the linked Threat row; the list below is deduplicated across both pages.
-
web:blog.qualys.com
With Qualys Policy Audit's out-of-the-box mitigation or Compensatory Controls, which reduce the risk of a vulnerability being exploited because the remediation ( fix / patch ) cannot be done immediately, these security controls are not recommended by any industry standards, such as CIS and DISA-STIG.
2026-05-21 21:53 UTC -
web:blogs.oracle.com
For more information about the Critical Patch Update program, see the security vulnerability remediation practices page located on the Oracle Trust Center.
2026-05-21 21:53 UTC -
web:cybersecuritynews.com
Microsoft's May 2026 Patch Tuesday lands with a heavy enterprise focus, fixing 120 vulnerabilities across Windows, Office, Azure, developer tools, and Microsoft 365 apps, including 29 remote code execution (RCE) flaws rated Critical.
2026-05-21 21:53 UTC -
web:portal.msrc.microsoft.com
The Security Update Guide provides information on the latest Microsoft security updates, helping users understand and address potential vulnerabilities effectively.
2026-05-21 21:53 UTC -
web:www.bleepingcomputer.com
Today is Microsoft's April 2026 Patch Tuesday with security updates for 167 flaws, including 2 zero-day vulnerabilities.
2026-05-21 21:53 UTC -
web:www.cisecurity.org
<p>Multiple vulnerabilities have been discovered in Microsoft products, the most severe of which could allow for remote code execution. Successful exploitation of the most severe of these vulnerabilities could result in an attacker gaining the same privileges as the logged-on user. Depending on the privileges associated with the user, an attacker could then install programs; view, change, or ...
2026-05-21 21:53 UTC -
web:www.helpnetsecurity.com
Microsoft has marked May 2026 Patch Tuesday by releasing fixes for 120+ CVE -numbered vulnerabilities, none of which are actively exploited.
2026-05-21 21:53 UTC -
web:www.oracle.com
This Critical Patch Update contains 481 new security patches across the product families listed below. Please note that an MOS note summarizing the content of this Critical Patch Update and other Oracle Software Security Assurance activities is located at April 2026 Critical Patch Update: Executive Summary and Analysis.
2026-05-21 21:53 UTC -
web:www.pcworld.com
This month's Patch Tuesday includes an actively exploited Office zero-day vulnerability and several critical RCE bugs in Windows and Remote Desktop.
2026-05-21 21:53 UTC -
web:www.techrepublic.com
Microsoft's April 2026 Patch Tuesday fixes 165 vulnerabilities, including two zero-days, in one of the company's largest monthly security updates.
2026-05-21 21:53 UTC -
web:bash.com
Buy The Fix ladies tops & t-shirts Online at Bash. Explore the wide range of The Fix ladies tops & t-shirts at best prices. Shop Now!
2026-06-03 22:32 UTC -
web:blog.qualys.com
RedSun is a zero-day LPE in Microsoft Defender with no patch available. Learn how to detect and mitigate it instantly using Qualys VMDR and TruRisk™ Eliminate.
2026-06-03 22:32 UTC -
web:epatch.pa.gov
Why does PATCH exist? Its purpose is to better enable the public to obtain criminal history record checks. The repository was created and is maintained in accordance with Pennsylvania's Criminal History Information Act contained in Chapter 91 of Title 18, Crimes Code. This Act also directs the Pennsylvania State Police (PSP) to disseminate criminal history data to criminal justice agencies ...
2026-06-03 22:32 UTC -
web:support.microsoft.com
This cumulative update for Windows Server 2022 (KB5082142), includes the latest security fixes and improvements, along with non-security updates from last month's optional preview release. To learn more about differences between security updates, optional non-security preview updates, out-of-band (OOB) updates, and continuous innovation, see Windows monthly updates explained. For information ...
2026-06-03 22:32 UTC -
web:www.freebsd.org
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 ============================================================================= FreeBSD-SA-26:22.libcasper Security ...
2026-06-03 22:32 UTC -
web:www.ibm.com
IBM Support, Fix Central All code (including Machine Code updates, samples, fixes or other software downloads) provided on the Fix Central website is subject to the terms of the applicable license agreements. Machine Code updates for Power Systems and System Storage are available for IBM machines that are under warranty or an IBM hardware maintenance service agreement. Some exceptions apply ...
2026-06-03 22:32 UTC -
web:www.oracle.com
Oracle Critical Patch Update Advisory - January 2026 Description A Critical Patch Update is a collection of patches for multiple security vulnerabilities. These patches address vulnerabilities in Oracle code and in third party components included in Oracle products. These patches are usually cumulative, but each advisory describes only the security patches added since the previous Critical ...
2026-06-03 22:32 UTC -
web:www.thehackerwire.com
How do I fix or mitigate CVE-2026-39461 ? To protect against CVE-2026-39461 , you should: (1) Apply the latest security patches from Freebsd, (2) Check official security advisories for specific remediation steps, (3) Update affected software to the latest version, and (4) Monitor your systems for any signs of exploitation.
2026-06-03 22:32 UTC -
web:www.youtube.com
Concert events listed are based on the artist featured in the video you are watching, channels you have subscribed to, your past activity while signed in to YouTube, including artists you search ...
2026-06-03 22:32 UTC
AI Forensic Analysis
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Raw JSON
The full cvelistV5 record. Download as CVE-2026-39461.json.
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unknown",
"modules": [
"libcasper"
],
"product": "FreeBSD",
"vendor": "FreeBSD",
"versions": [
{
"lessThan": "p9",
"status": "affected",
"version": "15.0-RELEASE",
"versionType": "release"
},
{
"lessThan": "p5",
"status": "affected",
"version": "14.4-RELEASE",
"versionType": "release"
},
{
"lessThan": "p14",
"status": "affected",
"version": "14.3-RELEASE",
"versionType": "release"
}
]
}
],
"credits": [
{
"lang": "en",
"type": "finder",
"value": "Joshua Rogers of AISLE Research Team"
}
],
"datePublic": "2026-05-20T23:00:00.000Z",
"descriptions": [
{
"lang": "en",
"value": "libcasper(3) communicates with helper processes via UNIX domain sockets, and uses the select(2) system call to wait for data to become available. However, it does not verify that its socket descriptor fits within select(2)'s descriptor set size limit of FD_SETSIZE (1024).\n\nAn attacker able to cause an application using libcasper(3) to allocate large file descriptors, e.g., by opening many descriptors and executing a program which is not careful to close them upon startup, may trigger stack corruption. If the target application runs with setuid root privileges, this could be used to escalate local privileges."
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-121",
"description": "CWE-121: Stack-based Buffer Overflow",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-05-21T09:20:26.126Z",
"orgId": "63664ac6-956c-4cba-a5d0-f46076e16109",
"shortName": "freebsd"
},
"references": [
{
"tags": [
"vendor-advisory"
],
"url": "https://security.freebsd.org/advisories/FreeBSD-SA-26:22.libcasper.asc"
}
],
"title": "select(2) file descriptor set overflow causes stack overflow",
"x_generator": {
"engine": "cvelib 1.8.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "63664ac6-956c-4cba-a5d0-f46076e16109",
"assignerShortName": "freebsd",
"cveId": "CVE-2026-39461",
"datePublished": "2026-05-21T09:20:26.126Z",
"dateReserved": "2026-04-28T15:08:10.637Z",
"dateUpdated": "2026-05-21T09:20:26.126Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}