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Fencer Vulns
critical 9.8

CVE-2020-14968 json

RSA-PSS signature validation vulnerability by prepending zeros in jsrsasign

published 2020-06-22 6 y ago modified 2026-06-22 4 mo ago also GHSA-q3gh-5r98-j4h3 , EUVD-2020-0507

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.9%
EPSS 2.9% chance of exploitation in 30 days, percentile 87%
public exploits
0
none known

Summary

An issue was discovered in the jsrsasign package before 8.0.17 for Node.js. Its RSASSA-PSS (RSA-PSS) implementation does not detect signature manipulation/modification by prepending '\0' bytes to a signature (it accepts these modified signatures as valid). An attacker can abuse this behavior in an application by creating multiple valid signatures where only one signature should exist. Also, an attacker might prepend these bytes with the goal of triggering memory corruption issues.

Patch / fix

  • npm jsrsasign 8.0.17
  • kjur jsrsasign 8.0.17

Exploit prediction

2.94% chance of exploitation in the next 30 days, higher than 87% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/kjur/jsrsasign/issues/438 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P
GitHub 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
npm jsrsasign
>=3.0.0, <8.0.17
8.0.17

Classification

Weakness
  • CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer

References

Sources

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.