CVE-2026-49852

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Source
https://cve.org/CVERecord?id=CVE-2026-49852
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-49852.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-49852
Aliases
Downstream
Related
Published
2026-07-17T19:14:58.019Z
Modified
2026-07-22T05:30:12.504320223Z
Severity
  • 8.7 (High) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N CVSS Calculator
Summary
joserfc: HS256/HS384/HS512 verify accepts empty/nil HMAC key (cross-language sibling of CVE-2026-45363)
Details

joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. Prior to 1.6.8, joserfc.jwt.decode accepts attacker-forged HMAC-signed tokens when the caller-supplied verification key is the empty string or None, because HMACAlgorithm.sign and HMACAlgorithm.verify in src/joserfc/rfc7518/jwsalgs.py pass the output of OctKey.getopkey(...) to hmac.new(...) and OctKey.import_key in src/joserfc/rfc7518/octkey.py only emits a SecurityWarning for keys shorter than 14 bytes without rejecting zero-length input. This issue is fixed in version 1.6.8.

Database specific 
{
    "cwe_ids": [
        "CWE-1391",
        "CWE-287",
        "CWE-326"
    ],
    "cna_assigner": "GitHub_M",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/49xxx/CVE-2026-49852.json"
}
References

Affected packages

Git / github.com/authlib/joserfc

Affected ranges

Type
GIT
Repo
https://github.com/authlib/joserfc
Events
Introduced
0 Unknown introduced commit / All previous commits are affected
Fixed
86d00910b2b2d2d07503fee9b572906daefab7f1
Fixed
ea1d9e301cc3f6d20d141058e4a0c4befc599b62
Database specific 
{
    "extracted_events": [
        {
            "introduced": "0"
        },
        {
            "fixed": "1.6.8"
        }
    ],
    "source": [
        "AFFECTED_FIELD",
        "REFERENCES"
    ]
}

Affected versions

0.*
0.10.0
0.11.0
0.11.1
0.12.0
0.2.0
0.3.0
0.4.0
0.5.0
0.6.0
0.7.0
0.8.0
0.9.0
1.*
1.0.0
1.0.1
1.0.2
1.0.3
1.0.4
1.1.0
1.2.0
1.2.1
1.2.2
1.3.0
1.3.1
1.3.2
1.3.3
1.4.0
1.4.1
1.4.3
1.5.0
1.6.0
1.6.1
1.6.2
1.6.3
1.6.4
1.6.5
1.6.7

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-49852.json"