libcryptx-perl — security advisory
CryptX versions before 0.088_001 for Perl compare AEAD authentication tags in non-constant time in the streaming decrypt_done path. The decrypt_done($tag) form compares it against the computed tag with memNE (memcmp() != 0), which short-circuits on the first differing byte, so its run time depends on the number of matching leading bytes. This affects all five AEAD modes: GCM, CCM, ChaCha20Poly1305, EAX and OCB. The one-shot *_decrypt_verify helpers are unaffected; they verify the tag inside libtomcrypt with a constant-time comparison. The timing difference is a tag-verification oracle. An attacker who can submit many candidate tags for the same nonce, ciphertext and associated data while measuring the timing precisely enough may recover the expected tag byte by byte and forge a message that verifies.
- Products
- libcryptx-perl
- Affected versions
- 0.077-1, 0.078-1, 0.080-1, 0.080-2, 0.081-1, 0.081-2, 0.082-1, 0.082.001-1, 0.084-1, 0.085-1, 0.085-1+deb13u1, 0.087-1, 0.087-2, 0.088-1, 0.089-1, 0.090-1, 0.090-1~bpo13+1, 0.091-1
- Fixed versions
- 0.089-1
- CVEs
- CVE-2026-13758
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 1 Nov 2026, 12:19 UTC · Revision 2
Source evidence
CryptX versions before 0.088_001 for Perl compare AEAD authentication tags in non-constant time in the streaming decrypt_done path. The decrypt_done($tag) form compares it against the computed tag with memNE (memcmp() != 0), which short-circuits on the first differing byte, so its run time depends on the number of matching leading bytes. This affects all five AEAD modes: GCM, CCM, ChaCha20Poly1305, EAX and OCB. The one-shot *_decrypt_verify helpers are unaffected; they verify the tag inside libtomcrypt with a constant-time comparison. The timing difference is a tag-verification oracle. An attacker who can submit many candidate tags for the same nonce, ciphertext and associated data while measuring the timing precisely enough may recover the expected tag byte by byte and forge a message that verifies.
osv:DEBIAN-CVE-2026-13758
libcryptx-perl
Fixed versions: Not specified
libcryptx-perl
Fixed versions: Not specified
libcryptx-perl
Fixed versions: 0.089-1
Complete source record
{
"id": "15b838cb8d15af5bc4868c3d98ba19ee85bf4e1888cce86215cfaa3d308a92d3",
"url": "https://osv.dev/vulnerability/DEBIAN-CVE-2026-13758",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "DEBIAN-CVE-2026-13758",
"summary": "CryptX versions before 0.088_001 for Perl compare AEAD authentication tags in non-constant time in the streaming decrypt_done path. The decrypt_done($tag) form compares it against the computed tag with memNE (memcmp() != 0), which short-circuits on the first differing byte, so its run time depends on the number of matching leading bytes. This affects all five AEAD modes: GCM, CCM, ChaCha20Poly1305, EAX and OCB. The one-shot *_decrypt_verify helpers are unaffected; they verify the tag inside libtomcrypt with a constant-time comparison. The timing difference is a tag-verification oracle. An attacker who can submit many candidate tags for the same nonce, ciphertext and associated data while measuring the timing precisely enough may recover the expected tag byte by byte and forge a message that verifies.",
"evidence": "osv:DEBIAN-CVE-2026-13758",
"products": [
{
"name": {
"value": "libcryptx-perl",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
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{
"value": "0.077-1",
"evidence": "/affected/0/versions"
},
{
"value": "0.078-1",
"evidence": "/affected/0/versions"
},
{
"value": "0.080-1",
"evidence": "/affected/0/versions"
},
{
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{
"value": "0.081-1",
"evidence": "/affected/0/versions"
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{
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{
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{
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{
"value": "0.084-1",
"evidence": "/affected/0/versions"
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{
"value": "0.085-1",
"evidence": "/affected/0/versions"
},
{
"value": "0.087-1",
"evidence": "/affected/0/versions"
},
{
"value": "0.087-2",
"evidence": "/affected/0/versions"
},
{
"value": "0.088-1",
"evidence": "/affected/0/versions"
},
{
"value": "0.089-1",
"evidence": "/affected/0/versions"
},
{
"value": "0.090-1",
"evidence": "/affected/0/versions"
},
{
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"evidence": "/affected/0/versions"
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{
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"evidence": "/affected/0/versions"
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]
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{
"name": {
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"evidence": "/affected/1/package/name"
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"evidence": "/affected/1/versions"
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{
"value": "0.085-1+deb13u1",
"evidence": "/affected/1/versions"
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{
"value": "0.087-1",
"evidence": "/affected/1/versions"
},
{
"value": "0.087-2",
"evidence": "/affected/1/versions"
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{
"value": "0.088-1",
"evidence": "/affected/1/versions"
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{
"value": "0.089-1",
"evidence": "/affected/1/versions"
},
{
"value": "0.090-1",
"evidence": "/affected/1/versions"
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{
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"evidence": "/affected/1/versions"
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{
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{
"name": {
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"evidence": "/affected/2/package/name"
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"affected_versions": [
{
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},
{
"value": "0.087-1",
"evidence": "/affected/2/versions"
},
{
"value": "0.087-2",
"evidence": "/affected/2/versions"
},
{
"value": "0.088-1",
"evidence": "/affected/2/versions"
}
]
}
],
"severity": "low",
"structured": {
"id": "DEBIAN-CVE-2026-13758",
"aliases": [
"DEBIAN-CVE-2026-13758"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
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"package": {
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"purl": "pkg:deb/debian/libcryptx-perl?arch=source&distro=bookworm",
"ecosystem": "Debian:12"
},
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"0.078-1",
"0.080-1",
"0.080-2",
"0.081-1",
"0.081-2",
"0.082-1",
"0.082.001-1",
"0.084-1",
"0.085-1",
"0.087-1",
"0.087-2",
"0.088-1",
"0.089-1",
"0.090-1",
"0.090-1~bpo13+1",
"0.091-1"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-13758.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "libcryptx-perl",
"purl": "pkg:deb/debian/libcryptx-perl?arch=source&distro=trixie",
"ecosystem": "Debian:13"
},
"versions": [
"0.085-1",
"0.085-1+deb13u1",
"0.087-1",
"0.087-2",
"0.088-1",
"0.089-1",
"0.090-1",
"0.090-1~bpo13+1",
"0.091-1"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-13758.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "0.089-1"
}
]
}
],
"package": {
"name": "libcryptx-perl",
"purl": "pkg:deb/debian/libcryptx-perl?arch=source&distro=forky",
"ecosystem": "Debian:14"
},
"versions": [
"0.085-1",
"0.087-1",
"0.087-2",
"0.088-1"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-13758.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
],
"modified": "2026-10-26T11:47:37.075162995Z",
"provider": "osv",
"upstream": [
"CVE-2026-13758"
],
"references": [
"https://security-tracker.debian.org/tracker/CVE-2026-13758"
]
},
"related_cves": [
{
"value": "CVE-2026-13758",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 450868,
"published_at": "2026-06-29T21:16:43.067+00:00"
}