CVE-2026-34932Public exploitNetwork attack vector

Token theft via same-origin mock response XSS

Published Apr 2, 2026 · Updated Apr 2, 2026

Stored XSS in Hoppscotch backend before 2026.3.0 allows remote attackers to run script through a crafted mock response. The mock server controller returns attacker-supplied active MIME types and bodies at a path on the backend origin without neutralization. Exploitation requires a victim to browse the crafted mock URL; the script then acts with the victim's backend session and can create and exfiltrate a personal access token.

CVSS severity8.5
High
EPSS probability0.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in Hoppscotch backend before 2026.3.0 allows remote attackers to run script through a crafted mock response. The mock server controller returns attacker-supplied active MIME types and bodies at a path on the backend origin without neutralization. Exploitation requires a victim to browse the crafted mock URL; the script then acts with the victim's backend session and can create and exfiltrate a personal access token.

The record

CVE
CVE-2026-34932
Published
Apr 2, 2026
Updated
Apr 2, 2026
Vendor
Hoppscotch
Product
Hoppscotch
Classifications
CWE-79, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 2, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 2, 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=< 2026.3.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Hoppscotch · Hoppscotchversion=< 2026.3.0

Published CVSS scores

9.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N
8.5GitHubCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA: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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 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')
T1189Drive-by Compromise

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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