Is there a public exploit for CVE-2026-99109?

No public exploit for CVE-2026-99109 was found in Exploit-DB, Metasploit, Nuclei templates or public proof-of-concept repositories. That is an absence of evidence rather than proof that none exists.

How severe is CVE-2026-99109?

CVE-2026-99109 scores CVSS 7.8 (v3.1), rated high. EPSS puts the chance of exploitation in the next 30 days at 0.16%.

7.8 High

In the Linux kernel, the following vulnerability has been resolved: smb: client: reject SetEA requests that do not fit the request buffer…

CVE-2026-99109

In the Linux kernel, the following vulnerability has been resolved: smb: client: reject SetEA requests that do not fit the request buffer CIFSSMBSetEA() copies the caller's extended attribute value into the SMB request buffer without checking that it fits. The requirement is stated in the source but was never implemented: /BB add length check to see if it would fit in negotiated SMB buffer size BB / / if (eavaluelen > buffersize - 512 (enough for header)) / if (eavaluelen) memcpy(parmdata->list.name + namelen + 1, eavalue, eavaluelen); The only bound applied on the way in is in cifsxattrset(): define MAXEAVALUESIZE CIFSMaxBufSize ... if (size > MAXEAVALUESIZE) CIFSMaxBufSize is the full payload capacity of the buffer, so a value of exactly that size leaves no room for the SMB header, the TRANS2 parameter block, the fealist header and the EA name that are written ahead of it in the same object. SendReceive() already enforces the correct limit on this very length: if (inlen > CIFSMaxBufSize + MAXCIFSHDRSIZE) but it is called after the copy has taken place. An unprivileged setxattr(2) on an SMB1 mount with a 250-byte name and a 16384-byte value writes 16384 bytes starting 345 bytes…

Assessment

CVSS: 7.8 (v3.1)
Severity: High
EPSS: 0.16% chance of exploitation in the next 30 days
Known exploited: Not listed in CISA KEV
Exploit availability: Nothing found in Exploit-DB, Metasploit, Nuclei or public PoC repositories
Published: 28 October 2026
Last updated: 31 October 2026
Affected: Linux
Assigner: Linux

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

At the source

EUVD (ENISA)

References

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