# CVE-2026-89607

## Summary

- **CVE ID:** CVE-2026-89607
- **Severity:** HIGH
- **CVSS Score:** 7.8 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H)
- **CWE:** N/A
- **Published:** Sep 11, 2026
- **Last Modified:** Sep 14, 2026

## Description

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]

## Affected Products

- Linux — Linux (237fead619984cc48818fe12ee0ceada3f55b012)
- Linux — Linux (2.6.19)
- Linux — Linux (0)
- Linux — Linux (6.12.109)
- Linux — Linux (6.18.50)
- Linux — Linux (7.2.4)
- Linux — Linux (7.3-rc1)
- Linux — Linux (5.10.270)
- Linux — Linux (5.15.221)
- Linux — Linux (6.1.188)
- Linux — Linux (6.6.157)

## References

- [CNA](https://git.kernel.org/stable/c/ccd13eff0e7356d2aa28b127b577e4e5ad4563f5)
- [CNA](https://git.kernel.org/stable/c/14cb36a500a5a3afbc955dbf69dabc565f1a3b26)
- [CNA](https://git.kernel.org/stable/c/a419c9ebfc9a40ee56aaad6dc68bfd67d400817b)
- [CNA](https://git.kernel.org/stable/c/5babe9c177c364521e3e682b949c5a8c47f4a441)
- [CNA](https://git.kernel.org/stable/c/2cd21340163494d312836c77c9fbfe2530b3d075)
- [CNA](https://git.kernel.org/stable/c/e2152d491ae62d96a32ed59778680a242af1fbc6)
- [CNA](https://git.kernel.org/stable/c/d2802414081184f79a619ede178aeef3aa989793)
- [CNA](https://git.kernel.org/stable/c/33e050cac841498b5175f0f385eee903fd98863c)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.16%
- **EPSS Percentile:** 6.0

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-18._