CVE-2025-68131: cbor2 — Exploit & Fix

Description

cbor2 provides encoding and decoding for the Concise Binary Object Representation (CBOR) serialization format. Starting in version 3.0.0 and prior to version 5.8.0, whhen a CBORDecoder instance is reused across multiple decode operations, values marked with the shareable tag (28) persist in memory and can be accessed by subsequent CBOR messages using the sharedref tag (29). This allows an attacker-controlled message to read data from previously decoded messages if the decoder is reused across trust boundaries. Version 5.8.0 patches the issue.

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CVSS v3.1 Score

7.5

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Weakness Type (CWE)

CWE-212 CWE-212

Affected Products

Vendor	Product	Versions
agronholm	cbor2	3.0.0 — 5.8.0

References

Advisories & Patches

https://github.com/agronholm/cbor2/pull/268 https://github.com/agronholm/cbor2/security/advisories/GHSA-wcj4-jw5j-44wh https://github.com/agronholm/cbor2/security/advisories/GHSA-wcj4-jw5j-44wh

Exploits

https://github.com/agronholm/cbor2/pull/268 https://github.com/agronholm/cbor2/security/advisories/GHSA-wcj4-jw5j-44wh https://github.com/agronholm/cbor2/security/advisories/GHSA-wcj4-jw5j-44wh

Frequently Asked Questions

What is CVE-2025-68131? +

cbor2 provides encoding and decoding for the Concise Binary Object Representation (CBOR) serialization format. Starting in version 3.0.0 and prior to version 5.8.0, whhen a CBORDecoder instance is reused across multiple decode operations, values marked with the shareable tag (28) persist in memory and can be accessed by subsequent CBOR messages using the sharedref tag (29). This allows an attacker-controlled message to read data from previously decoded messages if the decoder is reused across trust boundaries. Version 5.8.0 patches the issue. It has a CVSS v3.1 base score of 7.5 (HIGH).

How severe is CVE-2025-68131? +

CVE-2025-68131 has a CVSS v3.1 score of 7.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

What products are affected by CVE-2025-68131? +

CVE-2025-68131 affects products from agronholm, specifically: cbor2. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-68131? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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