CVE-2026-42794 Reflected XSS via backslash bypass in GraphiQL js_escape in absinthe_plug
Attackers can execute arbitrary JavaScript in victims' browsers via reflected XSS in the GraphiQL interface due to improper backslash escaping.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-42794?
CVE-2026-42794 is a low-severity cross-site scripting vulnerability in absinthe-graphql absinthe_plug, published on 8 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
Improper Neutralization of Input During Web Page Generation (XSS) vulnerability in absinthe-graphql absinthe_plug allows reflected cross-site scripting via the GraphiQL interface.
'Elixir.Absinthe.Plug.GraphiQL':js_escape/1 in lib/absinthe/plug/graphiql.ex escapes single quotes and newlines in the query GET parameter before embedding it in an inline JavaScript string, but does not escape backslashes. An attacker can bypass the escaping by prefixing a quote with a backslash (e.g. \'), breaking out of the string context and executing arbitrary JavaScript in the victim's browser.
This issue affects absinthe_plug: from 1.2.0 before 1.5.10.
Weakness: CWE-79
Which versions are affected by CVE-2026-42794?
3 open source packages ship an affected version, including absinthe_plug. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
absinthe_plug Hex | From 1.2.0 to 1.5.9 | None |
absinthe_plug Hex | From 1.2.0 to 1.5.9 | None |
absinthe_plug Hex | From 1.2.0 | 1.5.10 |
Products include Absinthe-Graphql Absinthe.plug.
How do I fix CVE-2026-42794?
Upgrade absinthe_plug to 1.5.10 or later.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-42794 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-42794 exists.
Sources
Also known as EEF-CVE-2026-42794, GHSA-c62g-j346-39v5.