Uncontrolled Recursion in CBOR2 - #VU162743
Published: November 9, 2026
Vulnerability identifier: #VU162743
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-674
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote unauthenticated attacker to crash services that decode untrusted CBOR using the cbor2 native extension.
The vulnerability exists due to shared-reference tags bypassing the max_depth guard in cbor2.loads(), permitting deeply nested map keys that trigger uncontrolled native recursion during hashing. A remote unauthenticated attacker can submit a crafted CBOR message to cause an uncatchable stack overflow that terminates the decoding process.
Affected software
CBOR2
Remediation
Install security update from vendor's website.
CBOR2 - update to 6.2.0