CVE-2026-89607
HighCVSS 7.8Exploitation Probability (EPSS)
Low risk6th percentile - higher than 6% of all known CVEs
Summary
In the Linux kernel, parse_tag_3_packet() fails to bound encrypted_key_size against ECRYPTFS_MAX_KEY_BYTES (64). When encrypted_key_size exceeds 64, decrypt_passphrase_encrypted_session_key() performs two out-of-bounds writes, corrupting the ecryptfs_auth_tok and ecryptfs_crypt_stat structures. Only AES-192 (cipher code 0x08) triggers this because it sets crypt_stat->key_size = 24 independently of encrypted_key_size.
Risk Assessment
The vulnerability can cause kernel memory corruption, system crash (panic), or potentially kernel code execution. Exploitation requires the ability to supply a crafted Tag 3 packet in an eCryptfs context, which may be achievable by a local user or via malicious input.
Recommendation
Update the Linux kernel to a version containing the fix that bounds encrypted_key_size to ECRYPTFS_MAX_KEY_BYTES (64). If immediate update is not possible, consider disabling or restricting eCryptfs usage with AES-192 until the patch is applied.
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Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: ecryptfs: reject oversized encrypted_key_size in parse_tag_3_packet parse_tag_3_packet() set encrypted_key_size from the Tag 3 packet body without bounding it against ECRYPTFS_MAX_KEY_BYTES (64). When encrypted_key_size > 64, decrypt_passphrase_encrypted_session_key() sets decrypted_key_size = encrypted_key_size and performs two out-of-bounds writes: 1. crypto_skcipher_decrypt() writes encrypted_key_size bytes into decrypted_key[64] via scatterlist, overflowing into the parent ecryptfs_auth_tok struct. 2. memcpy(crypt_stat->key, decrypted_key, decrypted_key_size) writes into crypt_stat->key[64], corrupting root_iv, keysig_list, and mutexes in ecryptfs_crypt_stat. Only AES-192 (cipher code 0x08) enables this because it sets crypt_stat->key_size = 24 independently of encrypted_key_size, allowing crypto_skcipher_setkey() to succeed while encrypted_key_size exceeds ECRYPTFS_MAX_KEY_BYTES. The PKI decryption path (parse_tag_65_packet) already validates decrypted_key_size <= ECRYPTFS_MAX_KEY_BYTES; the passphrase path omits this check. Bound encrypted_key_size against ECRYPTFS_MAX_KEY_BYTES (64) rather than ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES (512). The 64-byte limit also protects the 512-byte encrypted_key[] buffer, so the former 512-byte check is removed as redundant. [tyhicks: Adjust the code comment to refer to macros representing the buffer sizes rather than mentioning the buffer size values since they may change in the future]
Vulnerability data from NVD (NIST) · CISA KEV · EPSS