CVE-2026-111133
libfsapfs through 20260921 contains an integer underflow in libfsapfs_key_encrypted_key_read_data() that allows attackers to trigger heap out-of-bounds reads via crafted KEK attributes.
Does this matter?
Lower severity and a low EPSS score (0.20%). Track it; it rarely justifies an emergency change on its own.
Description
libfsapfs through 20260921 contains an integer underflow in libfsapfs_key_encrypted_key_read_data() that allows attackers to trigger heap out-of-bounds reads via crafted KEK attributes. Attackers can supply a crafted encrypted APFS image with malformed HMAC or wrapped KEK attribute lengths to crash fsapfsinfo, pyfsapfs, dfVFS or plaso and read adjacent heap memory before password checks.
- CVSS 4.0
- 6.9 MEDIUMCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
- EPSS
- 0.20% probability · 9th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-125
- Source
- disclosure@vulncheck.com
EPSS moved from 0.2% on 16 October 2026 to 0.2% on 26 October 2026.
References
- https://github.com/libyal/libfsapfs
- https://github.com/libyal/libfsapfs/blob/4c7c1c21f3cfc7d35f0b34b8a47f1f1562d27bbb/libfsapfs/libfsapfs_key_encrypted_key.c#L321-L333
- https://github.com/libyal/libfsapfs/blob/4c7c1c21f3cfc7d35f0b34b8a47f1f1562d27bbb/libfsapfs/libfsapfs_key_encrypted_key.c#L528-L540
- https://hackmd.io/@haind-pwn/libfsapfs-key-encrypted-key-attribute-oob-read
- https://www.vulncheck.com/advisories/libfsapfs-through-20260921-heap-out-of-bounds-read-via-libfsapfs-key-encrypted-key-read-data
- https://hackmd.io/@haind-pwn/libfsapfs-key-encrypted-key-attribute-oob-read
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.