CVE-2021-31537Public exploitNetwork attack vector

Reflected XSS via unescaped login query parameters

Published May 11, 2021 · Updated Aug 3, 2024

Reflected XSS in SIS Informatik SIS-REWE Go before 7.7 SP17 allows remote attackers to execute JavaScript via crafted login URLs. The login pages rewe/prod/web/index.php and rewe/prod/web/rewe_go_check.php return query values without filtering or escaping, causing supplied HTML or JavaScript to run in the browser. Exploitation requires a victim to open a malicious link; the script then executes in the vulnerable application's browser context.

CVSS severity6.1
Medium
EPSS probability7.78%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reflected XSS in SIS Informatik SIS-REWE Go before 7.7 SP17 allows remote attackers to execute JavaScript via crafted login URLs. The login pages rewe/prod/web/index.php and rewe/prod/web/rewe_go_check.php return query values without filtering or escaping, causing supplied HTML or JavaScript to run in the browser. Exploitation requires a victim to open a malicious link; the script then executes in the vulnerable application's browser context.

The record

CVE
CVE-2021-31537
Published
May 11, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 11, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:P/A:N

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

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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