Fail-open error handling in the data masking utility in Powertools for AWS Lambda (Python)

published 2026-10-01 38 d ago modified 2026-10-09 30 d ago also EUVD-2026-91063

cvss: 5.3; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.3%; EPSS 0.3% chance of exploitation in 30 days, percentile 23%
public exploits: 0; none known

A fail-open error handling issue within the data masking utility of Powertools for AWS Lambda (Python) might allow actors to read sensitive field values that the application intended to mask.

To remediate this issue, users should upgrade to version 3.35.0.

Patch / fix

links 1

github.com/aws-powertools/powertools-lambda-python/releases/tag/v3.35… release

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 37 d ago (2026-10-02)

Exploit prediction

0.31% chance of exploitation in the next 30 days, higher than 23% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	5.3	CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
CNA	4.0	6.0	CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
CNA	4.0	6.0	CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected products

AWS powertools-lambda-python

Classification

Weakness

CWE-390 Detection of Error Condition Without Action

References

github.com /aws-powertools/powertools-lambda-python/releases/tag/v3.35.0
patch
aws.amazon.com /security/security-bulletins/2026-123-aws/
vendor-advisory
github.com /aws-powertools/powertools-lambda-python/security/advisories/GHSA-3vxg-4xv2-jfh5
third-party-advisory

Sources

CVE List CVE-2026-104002
NVD CVE-2026-104002

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary