CVE catalog
CVE-2026-84308
phpseclib is a PHP secure communications library. Prior to 3.0.57 and 4.0.1, pure-PHP X25519 scalar multiplication in phpseclib/Math/PrimeField/Integer.php performs data-dependent conditional modular
- Severity
- Medium · CVSS 6.3
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N - Published
- Updated
- Source
- [NVD] · [CVE record]
- EPSS
- 0.33% · Oct 22, 2026
phpseclib is a PHP secure communications library. Prior to 3.0.57 and 4.0.1, pure-PHP X25519 scalar multiplication in phpseclib/Math/PrimeField/Integer.php performs data-dependent conditional modular reductions in add() and subtract(). During the Montgomery ladder in phpseclib/Crypt/EC/BaseCurves/Montgomery.php, the reduction behavior of each step depends on the secret scalar prefix, creating per-step timing and libgmp call-count observations that can reveal a reused 251-bit clamped private scalar. The phpseclib/Crypt/EC/Formats/Keys/MontgomeryPrivate.php derivation path invokes the pure-PHP multiplication without a native-engine check, while phpseclib/Crypt/EC/Formats/Keys/PKCS8.php reaches it when ext-sodium is unavailable. Exploitation requires a reused or long-lived X25519 private key, knowledge of the corresponding public key, execution of the pure-PHP path, and a local observer capable of resolving individual ladder steps or libgmp entry-point calls. Ephemeral X25519 keys, including phpseclib's normal SSH exchange path, are not affected. Recovery of the scalar permanently compromises operations that reuse that key. This issue is fixed in versions 3.0.57 and 4.0.1.
Vulnerable and fixed packages
Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.
| Distribution | Package | Release | Version | Status |
|---|---|---|---|---|
| Debian | phpseclib | sid | 1.0.30-1 | not affected |
| Debian | phpseclib | trixie | 1.0.23-6+deb13u3 | not affected |
| Debian | phpseclib | trixie-security | 1.0.23-6+deb13u1 | not affected |
| Debian | phpseclib | bookworm | 1.0.20-1+deb12u5 | not affected |
| Debian | phpseclib | bookworm-security | 1.0.20-1+deb12u3 | not affected |
| Debian | php-phpseclib | sid | 2.0.55-1 | not affected |
| Debian | php-phpseclib | forky | 2.0.55-1 | not affected |
| Debian | php-phpseclib | trixie | 2.0.48-3+deb13u3 | not affected |
| Debian | php-phpseclib | trixie-security | 2.0.48-3+deb13u1 | not affected |
| Debian | php-phpseclib | bookworm | 2.0.42-1+deb12u5 | not affected |
| Debian | php-phpseclib | bookworm-security | 2.0.42-1+deb12u3 | not affected |
| Debian | php-phpseclib3 | sid | 3.0.57-1 | fixed |
| Debian | php-phpseclib3 | forky | 3.0.57-1 | fixed |
| Debian | php-phpseclib3 | trixie | 3.0.43-2+deb13u3 | vulnerable |
| Debian | php-phpseclib3 | trixie-security | 3.0.43-2+deb13u1 | vulnerable |
| Debian | php-phpseclib3 | bookworm | 3.0.19-1+deb12u6 | vulnerable |
| Debian | php-phpseclib3 | bookworm-security | 3.0.19-1+deb12u4 | vulnerable |
| Composer | phpseclib/phpseclib | Not reported | 4.0.1 | fixed |
Fixed-version evidence
| Distribution | Package | Type | Release | Fixed version | Urgency | Origin | Bugs |
|---|---|---|---|---|---|---|---|
| Debian | phpseclib | source | sid | Not affected | unimportant | Not reported | Not reported |
| Debian | phpseclib | source | trixie | Not affected | unimportant | Not reported | Not reported |
| Debian | phpseclib | source | bookworm | Not affected | unimportant | Not reported | Not reported |
| Debian | php-phpseclib | source | sid | Not affected | unimportant | Not reported | Not reported |
| Debian | php-phpseclib | source | forky | Not affected | unimportant | Not reported | Not reported |
| Debian | php-phpseclib | source | trixie | Not affected | unimportant | Not reported | Not reported |
| Debian | php-phpseclib | source | bookworm | Not affected | unimportant | Not reported | Not reported |
| Debian | php-phpseclib3 | source | sid | 3.0.57-1 | not yet assigned | Not reported | Not reported |
| Debian | php-phpseclib3 | source | forky | 3.0.57-1 | not yet assigned | Not reported | Not reported |
| Debian | php-phpseclib3 | source | trixie | (unfixed) | not yet assigned | Not reported | Not reported |
| Debian | php-phpseclib3 | source | bookworm | (unfixed) | not yet assigned | Not reported | Not reported |
| Composer | phpseclib/phpseclib | composer | Not reported | 4.0.1 | Not reported | GHSA-Q97C-8QH3-FPC6 | Not reported |
Notes
[trixie] php-phpseclib3: Minor issue [bookworm] php-phpseclib3: Minor issue, local side-channel attack
OpenFactory catalog packages
[Debian 12 (Bookworm)]
- [php-phpseclib3]Affected
Details (4)
3.0.19-1+deb12u6· all · bookwormAffected
nvd · php-phpseclib3 · debian · bookworm; nvd · php-phpseclib3 · debian · 12
3.0.19-1+deb12u6· all · bookwormAffected
nvd · php-phpseclib3 · debian · bookworm; nvd · php-phpseclib3 · debian · 12
3.0.19-1+deb12u4· all · bookworm-securityAffected
nvd · php-phpseclib3 · debian · bookworm; nvd · php-phpseclib3 · debian · 12
3.0.19-1+deb12u4· all · bookworm-securityAffected
nvd · php-phpseclib3 · debian · bookworm; nvd · php-phpseclib3 · debian · 12
- [php-phpseclib]Not affected
Details (4)
2.0.42-1+deb12u5· all · bookwormNot affected
nvd · php-phpseclib · debian · bookworm
2.0.42-1+deb12u5· all · bookwormNot affected
nvd · php-phpseclib · debian · bookworm
2.0.42-1+deb12u3· all · bookworm-securityNot affected
nvd · php-phpseclib · debian · bookworm
2.0.42-1+deb12u3· all · bookworm-securityNot affected
nvd · php-phpseclib · debian · bookworm
- [php-seclib]Not affected
Source package: [phpseclib]
Details (4)
1.0.20-1+deb12u5· all · bookwormNot affected
nvd · phpseclib · debian · bookworm
1.0.20-1+deb12u5· all · bookwormNot affected
nvd · phpseclib · debian · bookworm
1.0.20-1+deb12u3· all · bookworm-securityNot affected
nvd · phpseclib · debian · bookworm
1.0.20-1+deb12u3· all · bookworm-securityNot affected
nvd · phpseclib · debian · bookworm
[Debian 13 (Trixie)]
- [php-phpseclib3]Affected
Details (4)
3.0.43-2+deb13u3· all · trixieAffected
nvd · php-phpseclib3 · debian · 13
3.0.43-2+deb13u3· all · trixieAffected
nvd · php-phpseclib3 · debian · 13
3.0.43-2+deb13u1· all · trixie-securityAffected
nvd · php-phpseclib3 · debian · 13
3.0.43-2+deb13u1· all · trixie-securityAffected
nvd · php-phpseclib3 · debian · 13
Observed:
References
- [https://github.com/advisories/GHSA-q97c-8qh3-fpc6]
- [https://nvd.nist.gov/vuln/detail/CVE-2026-84308]
- [https://osv.dev/vulnerability/DEBIAN-CVE-2026-84308]
- [https://security-tracker.debian.org/tracker/CVE-2026-84308]
[Debian Security Tracker] · [FIRST EPSS] · [GitHub Advisory Database] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database]