DEBIAN-CVE-2026-18036
In Bouncy Castle for Java before 1.86, NTRU reduced secret values with the % operator in three helpers whose reference implementations are deliberately division-free, so each reduction was carried out by an integer division whose latency depends on the secret operand. Polynomial.modQ divided by a variable divisor, which a compiler cannot strength-reduce to a multiply the way it can a constant one, so it emitted a division on every call including on the decapsulation path where the dividend derives from the private key; Polynomial.mod3 and NTRUSampling.mod3 divided the secret key polynomials f and g during key generation, the message polynomials r and m during encapsulation, and coefficients recovered during decapsulation. An attacker able to measure that timing can recover information about the NTRU private key. modQ now masks, which is exact because q is always a power of two, and mod3 uses the reference implementation's division-free fold and select; the results are unchanged.
DEBIAN-CVE-2026-18036
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: osv:DEBIAN-CVE-2026-18036
bouncycastle
Source reference: /affected/0/package/name
- Affected versions
- 1.72-2
Source reference:
/affected/0/versions1.77-1Source reference:
/affected/0/versions1.80-1Source reference:
/affected/0/versions1.80-2Source reference:
/affected/0/versions1.80-3Source reference:
/affected/0/versions1.86-1Source reference:
/affected/0/versions - Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
bouncycastle
Source reference: /affected/1/package/name
- Affected versions
- 1.80-3
Source reference:
/affected/1/versions1.86-1Source reference:
/affected/1/versions - Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
bouncycastle
Source reference: /affected/2/package/name
- Affected versions
- 1.80-3
Source reference:
/affected/2/versions - Fixed versions
- 1.86-1
Source reference:
/affected/2/ranges - Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "bouncycastle",
"purl": "pkg:deb/debian/bouncycastle?arch=source&distro=bookworm",
"ecosystem": "Debian:12"
},
"versions": [
"1.72-2",
"1.77-1",
"1.80-1",
"1.80-2",
"1.80-3",
"1.86-1"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-18036.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "bouncycastle",
"purl": "pkg:deb/debian/bouncycastle?arch=source&distro=trixie",
"ecosystem": "Debian:13"
},
"versions": [
"1.80-3",
"1.86-1"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-18036.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "1.86-1"
}
]
}
],
"package": {
"name": "bouncycastle",
"purl": "pkg:deb/debian/bouncycastle?arch=source&distro=forky",
"ecosystem": "Debian:14"
},
"versions": [
"1.80-3"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-18036.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
]- Related CVEs
- CVE-2026-18036
Source reference:
/upstream
Publisher severity
high
Source reference: /severity/0/score
- Event
- #72874 · Revision 1
- Added to Heist Feed
- Publisher date