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CVE-2025-64076

24
FAUCET Score

CVE-2025-64076 describes multiple vulnerabilities in the cbor2 library, specifically in versions up to 5.7.0, affecting its C extension decoder. These include an integer underflow leading to an out-of-bounds read and a memory leak due to unreleased Python object references, both occurring within the decode_definite_long_string() function. The vulnerabilities carry a CVSS score of 7.5 (High), indicating a critical risk of denial of service through process crashes or memory exhaustion. Exploitation is remote, unauthenticated, and requires specially-crafted CBOR data. There is currently no evidence of active exploitation, public exploit code, or significant community discussion.

Impacted Technologies

VendorProductVersion(s)CPE
<= 5.7.0CPE matchmatch criteria
cpe:2.3:a:agronholm:cbor2:*:*:*:*:*:python:*:*

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.47%
Probability of exploitation in next 30 days
EPSS Percentile
37.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0047 is in the 16th percentile among its peer group of 51,506 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (1)

github_advisorypatch availablevia nvd_reference
View patch

Vendor Advisories (1)

redhatCVE-2025-64076Important

cbor2: cbor2: Integer Underflow and Memory Leak leading to Denial of Service

Nov 18, 2025

References

github.com / agronholm/cbor2/commit/851473490281f82d82560b2368284ef33cf6e8f9
Patch
github.com / agronholm/cbor2/issues/264
ExploitIssue Tracking
github.com / agronholm/cbor2/pull/265
ExploitIssue TrackingPatch