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Fencer Intel
high 7.5

CVE-2020-14966 json

ECDSA signature validation vulnerability by accepting wrong ASN.1 encoding in jsrsasign

published 6y ago modified 4mo ago also GHSA-p8c3-7rj8-q963 , EUVD-2020-0505

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.2%
EPSS 1.2% chance of exploitation in 30 days, percentile 67%
public exploits
0
none known

Summary

An issue was discovered in the jsrsasign package through 8.0.18 for Node.js. It allows a malleability in ECDSA signatures by not checking overflows in the length of a sequence and '0' characters appended or prepended to an integer. The modified signatures are verified as valid. This could have a security-relevant impact if an application relied on a single canonical signature.

Patch / fix

  • npm jsrsasign 8.0.19

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Exploit prediction

1.15% chance of exploitation in the next 30 days, higher than 67% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • github.com https://github.com/kjur/jsrsasign/issues/437 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:P/A:N
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Affected packages

ecosystem package affected fixed in
npm jsrsasign
>=4.0.0, <8.0.19
8.0.19

Classification

Weakness
  • CWE-347 Improper Verification of Cryptographic Signature

References

Sources

Fencer Intel 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.