CVE-2020-37168Public exploitNetwork attack vector

Payment forgery via brute-forced SHA-1 signing key

Published May 13, 2026 · Updated May 13, 2026

Weak payment-signature hashing in BPCE Payment Services Systempay 1.0 allows remote attackers to recover the production secret key. The integration exposes signed POST fields and their SHA-1 digest, allowing offline comparison of candidate 16-character keys against a captured signature. A merchant must use the Systempay SHA-1 signing flow and expose a legitimate payment submission; key recovery permits forged signatures and altered transaction amounts.

CVSS severity9.3
Critical
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Weak payment-signature hashing in BPCE Payment Services Systempay 1.0 allows remote attackers to recover the production secret key. The integration exposes signed POST fields and their SHA-1 digest, allowing offline comparison of candidate 16-character keys against a captured signature. A merchant must use the Systempay SHA-1 signing flow and expose a legitimate payment submission; key recovery permits forged signatures and altered transaction amounts.

The record

CVE
CVE-2020-37168
Published
May 13, 2026
Updated
May 13, 2026
Vendor
BPCE Payment Services
Product
Systempay
Classifications
CWE-328, T1565.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 13, 2026CVE publishedPublication date reported by the CVE source.
  2. May 13, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

BPCE Payment Services · Systempayversion=1.0

Published CVSS scores

9.3VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
9.8VulnCheckCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-328Use of Weak Hash
T1565.002Transmitted Data Manipulation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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