Reflected XSS via GraphiQL backslash escape bypass
Published May 8, 2026 · Updated May 8, 2026
Reflected XSS in Absinthe.Plug 1.2.0 through 1.5.9 allows remote attackers to execute JavaScript via a crafted GraphiQL query URL. The GraphiQL js_escape/1 function embeds the query GET parameter in an inline JavaScript string after escaping quotes and newlines but leaves backslashes unescaped, so a backslash-prefixed quote terminates the string. Exploitation requires a reachable GraphiQL route and a victim to open the crafted URL; successful execution can read or alter data accessible to that browser session.
Summary
What happened
Reflected XSS in Absinthe.Plug 1.2.0 through 1.5.9 allows remote attackers to execute JavaScript via a crafted GraphiQL query URL. The GraphiQL js_escape/1 function embeds the query GET parameter in an inline JavaScript string after escaping quotes and newlines but leaves backslashes unescaped, so a backslash-prefixed quote terminates the string. Exploitation requires a reachable GraphiQL route and a victim to open the crafted URL; successful execution can read or alter data accessible to that browser session.
The record
- CVE
- CVE-2026-42794
- Published
- May 8, 2026
- Updated
- May 8, 2026
- Vendor
- Absinthe
- Product
- Absinthe.Plug
- Classifications
- CWE-79, CAPEC-86, T1189
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 8, 2026CVE publishedPublication date reported by the CVE source.
- May 8, 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.
- Affected versionversion=1.2.0 <*
- Affected versionversion=26241817cb4b9be4de3f5972c5fba3d36de3d713 <23a0d5658d32420086711adf4ce8f05febb09963
What conditions does exploitation require?
What is affected?
Published CVSS scores
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.
Weakness, pattern, technique
Public exploit references
- GraphiQL backslash-bypass reproductionproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
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