Answer in brief
CVE-2026-63909 records a High severity (CVSS 8.1) vulnerability in ksmbd: OOB read regression in smb_check_perm_dacl() ACE-walk loops. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 8.1. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Product | Affected versions | Fixed versions |
|---|---|---|
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:linux:linux_kernel:7.1:rc3:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:linux:linux_kernel:7.1:rc4:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:linux:linux_kernel:7.1:rc5:*:*:*:*:*:* | Not reported | Not reported |
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=282cbbb476b9f35793452bc461934af4c7eca169 <5500ba1d410aed1eded3eb04a76b10cfb4409334 || >=f20adc4ef7428bc485ee83fd1a592252fb87718b <f6324b4240cf0b26a84c33f68a1222d727ff4af2 || >=325d4ac11f526cb8964cff14548ccf02d8c756d8 <0fe08c5776a798f46df1fd74b331be26bdd644d6 || >=95e5aa3c3261da8c95b27d7aecf8ee39b9f86a4c <d333af32e4451285e427f2d9c29de3a39f6f6d48 || >=90089584b2e25c4510b7b987387b4405f0673ece <94215d55b09445993929f4fc966061d61de74929 || >=151b1799861fde38087c08f613abc2843ef597b0 <4f7c131d2bdd7cd64b96f60d10be5ea72253f520 || >=d07b26f39246a82399661936dd0c853983cfade7 <0e60dafe97eca61721f3db456f97d97a80c6c8ae | 5500ba1d410aed1eded3eb04a76b10cfb4409334, f6324b4240cf0b26a84c33f68a1222d727ff4af2, 0fe08c5776a798f46df1fd74b331be26bdd644d6, d333af32e4451285e427f2d9c29de3a39f6f6d48, 94215d55b09445993929f4fc966061d61de74929, 4f7c131d2bdd7cd64b96f60d10be5ea72253f520, 0e60dafe97eca61721f3db456f97d97a80c6c8ae |
| Linux/Linuxgeneric | >=6.6.140 <6.6.143 || >=6.12.84 <6.12.93 || >=6.18.25 <6.18.35 || >=7.0.2 <7.0.12 | 6.6.143, 6.12.93, 6.18.35, 7.0.12 |
Published upstream
Jul 19, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 30, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 5, 2026
In the Linux kernel, the following vulnerability has been resolved: ksmbd: OOB read regression in smb_check_perm_dacl() ACE-walk loops Commit d07b26f39246 ("ksmbd: require minimum ACE size in smb_check_perm_dacl()") introduced a transposed bounds check: if (offsetof(struct smb_ace, sid) + aces_size < CIFS_SID_BASE_SIZE) Since offsetof(..sid) is 8 and CIFS_SID_BASE_SIZE is 8, this evaluates to `aces_size < 0`. Because `aces_size` is always non-negative, this check becomes dead code and never breaks the loop. Worse, that commit removed the old 4-byte guard, meaning the loop now reads `ace->size` (offset 2) even when `aces_size` is 0-3 bytes. This re-opens a 2-byte heap out-of-bounds (OOB) read past the pntsd allocation during subsequent SMB2_CREATE operations. Fix this by properly transposing the comparison to require at least 16 bytes (8-byte offset + 8-byte SID base), matching the correct form used in smb_inherit_dacl().
Quoted source text, attributed separately from HOL analysis.