XML External Entity (XXE) vulnerability in esaml (and its forks) allows an attacker to cause the system to read local files and incorporate their contents into processed SAML documents, and potentially perform SSRF via crafted SAML messages.
esaml parses attacker-controlled SAML messages using xmerl_scan:string/2 before signature verification without disabling XML entity expansion. On Erlang/OTP versions before 27, Xmerl allows entities by default, enabling pre-signature XXE attacks. An attacker can cause the host to read local files (e.g., Kubernetes-mounted secrets) into the SAML document. If the attacker is not a trusted SAML SP, signature verification will fail and the document is discarded, but file contents may still be exposed through logs or error messages.
This issue affects all versions of esaml, including forks by arekinath, handnot2, and dropbox. Users running on Erlang/OTP 27 or later are not affected due to Xmerl defaulting to entities disabled.
esaml parses attacker-controlled SAML messages using xmerl_scan:string/2 before signature verification without disabling XML entity expansion. On Erlang/OTP versions before 27, Xmerl allows entities by default, enabling pre-signature XXE attacks. An attacker can cause the host to read local files (e.g., Kubernetes-mounted secrets) into the SAML document. If the attacker is not a trusted SAML SP, signature verification will fail and the document is discarded, but file contents may still be exposed through logs or error messages.
This issue affects all versions of esaml, including forks by arekinath, handnot2, and dropbox. Users running on Erlang/OTP 27 or later are not affected due to Xmerl defaulting to entities disabled.
Project Subscriptions
Advisories
No advisories yet.
Fixes
Solution
No solution given by the vendor.
Workaround
Upgrade to Erlang/OTP 27 or later. Starting with OTP 27, xmerl_scan disables entity expansion by default, which mitigates this vulnerability without changes to esaml.
References
| Link | Providers |
|---|---|
| https://cna.erlef.org/cves/CVE-2026-28809.html |
|
History
Mon, 23 Mar 2026 10:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | XML External Entity (XXE) vulnerability in esaml (and its forks) allows an attacker to cause the system to read local files and incorporate their contents into processed SAML documents, and potentially perform SSRF via crafted SAML messages. esaml parses attacker-controlled SAML messages using xmerl_scan:string/2 before signature verification without disabling XML entity expansion. On Erlang/OTP versions before 27, Xmerl allows entities by default, enabling pre-signature XXE attacks. An attacker can cause the host to read local files (e.g., Kubernetes-mounted secrets) into the SAML document. If the attacker is not a trusted SAML SP, signature verification will fail and the document is discarded, but file contents may still be exposed through logs or error messages. This issue affects all versions of esaml, including forks by arekinath, handnot2, and dropbox. Users running on Erlang/OTP 27 or later are not affected due to Xmerl defaulting to entities disabled. | |
| Title | XXE in esaml SAML library allows local file read and potential SSRF | |
| First Time appeared |
Arekinath
Arekinath esaml Dropbox Dropbox esaml Handnot2 Handnot2 esaml |
|
| Weaknesses | CWE-611 | |
| CPEs | cpe:2.3:a:arekinath:esaml:*:*:*:*:*:*:*:* cpe:2.3:a:dropbox:esaml:*:*:*:*:*:*:*:* cpe:2.3:a:handnot2:esaml:*:*:*:*:*:*:*:* |
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| Vendors & Products |
Arekinath
Arekinath esaml Dropbox Dropbox esaml Handnot2 Handnot2 esaml |
|
| References |
| |
| Metrics |
cvssV4_0
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Projects
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Status: PUBLISHED
Assigner: EEF
Published:
Updated: 2026-03-23T10:09:29.233Z
Reserved: 2026-03-03T14:40:00.590Z
Link: CVE-2026-28809
No data.
Status : Received
Published: 2026-03-23T11:16:24.343
Modified: 2026-03-23T11:16:24.343
Link: CVE-2026-28809
No data.
OpenCVE Enrichment
No data.
Weaknesses