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Fencer Intel
medium 6.5

CVE-2016-10555 json

Forgeable Public/Private Tokens in jwt-simple

published 2018-05-31 8 y ago modified 2026-06-17 4 mo ago also GHSA-vgrx-w6rg-8fqf , EUVD-2018-0779

cvss
6.5
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
4.7%
EPSS 4.7% chance of exploitation in 30 days, percentile 91%
public exploits
0
none known

Summary

Since "algorithm" isn't enforced in jwt.decode()in jwt-simple 0.3.0 and earlier, a malicious user could choose what algorithm is sent sent to the server. If the server is expecting RSA but is sent HMAC-SHA with RSA's public key, the server will think the public key is actually an HMAC private key. This could be used to forge any data an attacker wants.

Patch / fix

  • npm jwt-simple 0.3.1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2016-10555 updated cvss 6.5

nodejs-jwt-simple: Missing algorithm parameter in jwt.js:jwt_decode() can allow attackers to bypass JWT signature verification

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

4.73% chance of exploitation in the next 30 days, higher than 91% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.0 6.5 CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
NVD 2.0 4.0 AV:N/AC:L/Au:S/C:N/I:P/A:N

Affected packages

ecosystem package affected fixed in
npm jwt-simple
<0.3.1
0.3.1

Affected products

  • HackerOne jwt-simple node module

Classification

Weakness

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.