`libparsec_crypto` does not check for weak order point of curve 25519

published 2026-01-29 9 mo ago modified 2026-06-17 4 mo ago also EUVD-2025-206513

cvss: 8.3; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.3%; EPSS 0.3% chance of exploitation in 30 days, percentile 23%
public exploits: 0; none known

Parsec is a cloud-based application for cryptographically secure file sharing. In versions on the 3.x branch prior to 3.6.0, `libparsec_crypto`, a component of the Parsec application, does not check for weak order point of Curve25519 when compiled with its RustCrypto backend. In practice this means an attacker in a man-in-the-middle position would be able to provide weak order points to both parties in the Diffie-Hellman exchange, resulting in a high probability to for both parties to obtain the same shared key (hence leading to a successful SAS code exchange, misleading both parties into thinking no MITM has occurred) which is also known by the attacker. Note only Parsec web is impacted (as Parsec desktop uses `libparsec_crypto` with the libsodium backend). Version 3.6.0 of Parsec patches the issue.

Patch / fix

fixed in 1 links 4

parsec.cloud parsec 3.6.0

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: total
Assessed: 9 mo ago (2026-01-29)

Exploit prediction

0.30% chance of exploitation in the next 30 days, higher than 23% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/Scille/parsec-cloud/security/advisories/GHSA-hrc9-gm58-pgj9 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	3.1	8.3	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L
NVD	3.1	7.1	CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:L

Affected products

Scille parsec-cloud

Classification

Weakness

CWE-327 Use of a Broken or Risky Cryptographic Algorithm
CWE-1240 Use of a Cryptographic Primitive with a Risky Implementation

References

Sources

CVE List CVE-2025-62514
NVD CVE-2025-62514

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary