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CVE-2020-27846

XML Processing error in github.com/crewjam/saml

9.8 CriticalFix available

A signature verification vulnerability exists in crewjam/saml. This flaw allows an attacker to bypass SAML Authentication. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

4.93%Up 3.3 points since Apr 14, 2021
90%50%10%1%

What each source reports

NVD Score used 9.8

A signature verification vulnerability exists in crewjam/saml. This flaw allows an attacker to bypass SAML Authentication. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability.

Record
CVE-2020-27846
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS 2.0
10.0 HighAV:N/AC:L/Au:N/C:C/I:C/A:C
Weakness
CWE-115
Updated
2026-11-02
CVE List No score

A signature verification vulnerability exists in crewjam/saml. This flaw allows an attacker to bypass SAML Authentication. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability.

Record
CVE-2020-27846
Weakness
CWE-115
Updated
2026-11-02
EUVDEUVD-2021-1260 No score

A signature verification vulnerability exists in crewjam/saml. This flaw allows an attacker to bypass SAML Authentication. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability.

Record
EUVD-2021-1260
Updated
2026-11-03
GitHub AdvisoriesGHSA-4hq8-gmxx-h6w9 9.8

XML Processing error in github.com/crewjam/saml

Impact

There are three vulnerabilities in the go encoding/xml package that can allow an attacker to forge part of a signed XML document. For details on this vulnerability see xml-roundtrip-validator

Patches

In version 0.4.3, all XML input is validated prior to being parsed.

Record
GHSA-4hq8-gmxx-h6w9
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-115, CWE-287
Updated
2026-11-02
OSV 9.8

A signature verification vulnerability exists in crewjam/saml. This flaw allows an attacker to bypass SAML Authentication. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability.

Record
CVE-2020-27846
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVGHSA-4hq8-gmxx-h6w9 9.8

XML Processing error in github.com/crewjam/saml

Impact

There are three vulnerabilities in the go encoding/xml package that can allow an attacker to forge part of a signed XML document. For details on this vulnerability see xml-roundtrip-validator

Patches

In version 0.4.3, all XML input is validated prior to being parsed.

Record
GHSA-4hq8-gmxx-h6w9
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-115, CWE-287
Updated
2026-11-02
Show 5 moreShow less
OSVOESA-2021-1445 9.8

grafana security update

Grafana is an open source, feature rich metrics dashboard and graph editor for Graphite, InfluxDB & OpenTSDB.

Security Fix(es):

Grafana before 7.1.0-beta 1 allows XSS via a query alias for the ElasticSearch datasource.(CVE-2020-24303)

A signature verification vulnerability exists in crewjam/saml. This flaw allows an attacker to bypass SAML Authentication. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability.(CVE-2020-27846)

The snapshot feature in Grafana 6.7.3 through 7.4.1 can allow an unauthenticated remote attackers to trigger a Denial of Service via a remote API call if a commonly used configuration is set.(CVE-2021-27358)

One of the usage insights HTTP API endpoints in Grafana Enterprise 6.x before 6.7.6, 7.x before 7.3.10, and 7.4.x before 7.4.5 is accessible without any authentication. This allows any unauthenticated user to send an unlimited number of requests to the endpoint, leading to a denial of service (DoS) attack against a Grafana Enterprise instance.(CVE-2021-28148)

The team sync HTTP API in Grafana Enterprise 6.x before 6.7.6, 7.x before 7.3.10, and 7.4.x before 7.4.5 has an Incorrect Access Control issue. On Grafana instances using an external authentication service and having the EditorsCanAdmin feature enabled, this vulnerability allows any authenticated user to add external groups to any existing team. This can be used to grant a user team permissions that the user isn't supposed to have.(CVE-2021-28147)

Grafana is an open source data visualization platform. In affected versions unauthenticated and authenticated users are able to view the snapshot with the lowest database key by accessing the literal paths: /dashboard/snapshot/:key, or /api/snapshots/:key. If the snapshot "public_mode" configuration setting is set to True (vs default of False), unauthenticated users are able to delete the snapshot with the lowest database key by accessing the literal path: /api/snapshots-delete/:deleteKey. Regardless of the snapshot "public_mode" setting, authenticated users are able to delete the snapshot with the lowest database key by accessing the literal paths: /api/snapshots/:key, or /api/snapshots-delete/:deleteKey. The combination of deletion and viewing enables a complete walk through all snapshot data while resulting in complete snapshot data loss. This issue has been resolved in versions 8.1.6 and 7.5.11. If for some reason you cannot upgrade you can use a reverse proxy or similar to block access to the literal paths: /api/snapshots/:key, /api/snapshots-delete/:deleteKey, /dashboard/snapshot/:key, and /api/snapshots/:key. They have no normal function and can be disabled without side effects.(CVE-2021-39226)

Record
OESA-2021-1445
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVRHSA-2021:1859 9.8

Red Hat Security Advisory: grafana security, bug fix, and enhancement update

Record
RHSA-2021:1859
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVRLSA-2021:1859 9.8

Moderate: grafana security, bug fix, and enhancement update

Grafana is an open source, feature rich metrics dashboard and graph editor for Graphite, InfluxDB & OpenTSDB.

The following packages have been upgraded to a later upstream version: grafana (7.3.6). (BZ#1850471)

Security Fix(es):

  • crewjam/saml: authentication bypass in saml authentication (CVE-2020-27846)

  • grafana: XSS via a query alias for the Elasticsearch and Testdata datasource (CVE-2020-24303)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Additional Changes:

For detailed information on changes in this release, see the Rocky Linux 8.4 Release Notes linked from the References section.

Record
RLSA-2021:1859
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVBIT-grafana-2020-27846 No score

A signature verification vulnerability exists in crewjam/saml. This flaw allows an attacker to bypass SAML Authentication. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability.

Record
BIT-grafana-2020-27846
Updated
2026-11-02
OSVGO-2021-0058 No score

Signature validation bypass due to XML processing error in github.com/crewjam/saml

Due to the behavior of encoding/xml, a crafted XML document may cause XML Digital Signature validation to be entirely bypassed, causing an unsigned document to appear signed.

Record
GO-2021-0058
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
github.com/crewjam/saml
Go
before 0.4.3
0.4.3
grafana
Bitnami
before 6.7.5, 7.0.0 up to 7.2.3, 7.3.0 up to 7.3.6
6.7.57.2.37.3.6
grafana
openEuler:20.03-LTS-SP1
From an advisory covering 6 CVEs
before 7.5.11-1.oe1
7.5.11-1.oe1
grafana
openEuler:20.03-LTS-SP2
From an advisory covering 6 CVEs
before 7.5.11-1.oe1
7.5.11-1.oe1
grafana
Red Hat:enterprise_linux:8::appstream
From an advisory covering 2 CVEs
before 0:7.3.6-2.el8
0:7.3.6-2.el8
grafana-debuginfo
Red Hat:enterprise_linux:8::appstream
From an advisory covering 2 CVEs
before 0:7.3.6-2.el8
0:7.3.6-2.el8
grafana
Rocky Linux:8
From an advisory covering 2 CVEs
before 0:7.3.6-2.el8
0:7.3.6-2.el8

History

History
RecordedChangedSources
affected, facts
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2020-27846 is a critical vulnerability (CVSS 9.8) in Saml Project Saml, published December 21, 2020. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 4.93%, the 92nd percentile. Fixed in github.com/crewjam/saml 0.4.3.

References

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