XXE in esaml SAML library allows local file read and potential SSRF
Summary
| CVE | CVE-2026-28809 |
|---|---|
| State | PUBLISHED |
| Assigner | EEF |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-03-23 11:16:24 UTC |
| Updated | 2026-04-06 17:17:09 UTC |
| 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. |
Risk And Classification
Primary CVSS: v4.0 6.3 MEDIUM from 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Problem Types: CWE-611 | CWE-611 CWE-611 Improper Restriction of XML External Entity Reference
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | Secondary | 6.3 | MEDIUM | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/C... |
| 4.0 | CNA | CVSS | 6.3 | MEDIUM | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N |
CVSS v4.0 Breakdown
Attack Vector
NetworkAttack Complexity
LowAttack Requirements
PresentPrivileges Required
NoneUser Interaction
NoneConfidentiality
LowIntegrity
NoneAvailability
NoneSub Conf.
NoneSub Integrity
NoneSub Availability
NoneCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Dropbox | Esaml | Not specified | Not specified |
| CNA | Arekinath | Esaml | Not specified | Not specified |
| CNA | Handnot2 | Esaml | Not specified | Not specified |
| CNA | Dropbox | Esaml | Not specified | Not specified |
| CNA | Jump-App | Esaml | affected bab85efde7c136911402a881ca55173759467a26 git | Not specified |
| CNA | Jump-App | Esaml | unaffected bab85efde7c136911402a881ca55173759467a26 git | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| cna.erlef.org/cves/CVE-2026-28809.html | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | cna.erlef.org | |
| osv.dev/vulnerability/EEF-CVE-2026-28809 | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | osv.dev | |
| github.com/Jump-App/esaml/commit/bab85efde7c136911402a881ca55173759467a26 | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | github.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Bryan Lynch (en)
CNA: Jonatan Männchen / EEF (en)
Additional Advisory Data
Workarounds
CNA: 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.
There are currently no legacy QID mappings associated with this CVE.