ecryptfs: reject oversized encrypted_key_size in parse_tag_3_packet

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-89607
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-11 20:19:45 UTC
Updated2026-09-14 13:19:14 UTC
DescriptionIn 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]

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

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

EPSS: 0.001630000 probability, percentile 0.058580000 (date 2026-09-14)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 237fead619984cc48818fe12ee0ceada3f55b012 2cd21340163494d312836c77c9fbfe2530b3d075 git Not specified
CNA Linux Linux affected 237fead619984cc48818fe12ee0ceada3f55b012 e2152d491ae62d96a32ed59778680a242af1fbc6 git Not specified
CNA Linux Linux affected 237fead619984cc48818fe12ee0ceada3f55b012 d2802414081184f79a619ede178aeef3aa989793 git Not specified
CNA Linux Linux affected 237fead619984cc48818fe12ee0ceada3f55b012 33e050cac841498b5175f0f385eee903fd98863c git Not specified
CNA Linux Linux affected 237fead619984cc48818fe12ee0ceada3f55b012 ccd13eff0e7356d2aa28b127b577e4e5ad4563f5 git Not specified
CNA Linux Linux affected 237fead619984cc48818fe12ee0ceada3f55b012 14cb36a500a5a3afbc955dbf69dabc565f1a3b26 git Not specified
CNA Linux Linux affected 237fead619984cc48818fe12ee0ceada3f55b012 a419c9ebfc9a40ee56aaad6dc68bfd67d400817b git Not specified
CNA Linux Linux affected 237fead619984cc48818fe12ee0ceada3f55b012 5babe9c177c364521e3e682b949c5a8c47f4a441 git Not specified
CNA Linux Linux affected 2.6.19 Not specified
CNA Linux Linux unaffected 2.6.19 semver Not specified
CNA Linux Linux unaffected 5.10.270 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.221 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.188 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.157 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.109 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.50 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.4 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/ccd13eff0e7356d2aa28b127b577e4e5ad4563f5 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/14cb36a500a5a3afbc955dbf69dabc565f1a3b26 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/d2802414081184f79a619ede178aeef3aa989793 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/e2152d491ae62d96a32ed59778680a242af1fbc6 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/2cd21340163494d312836c77c9fbfe2530b3d075 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/5babe9c177c364521e3e682b949c5a8c47f4a441 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/33e050cac841498b5175f0f385eee903fd98863c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/a419c9ebfc9a40ee56aaad6dc68bfd67d400817b 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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