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CVE-2020-29509

Authentication Bypass in github.com/russellhaering/gosaml2

9.8 CriticalFix available

The encoding/xml package in Go (all versions) does not correctly preserve the semantics of attribute namespace prefixes during tokenization round-trips, which allows an attacker to craft inputs that behave in conflicting ways during different stages of processing in affected downstream applications.

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

2.10%Up 1.5 points since Apr 14, 2021
90%50%10%1%

What each source reports

CVE List Score used 9.8

The encoding/xml package in Go (all versions) does not correctly preserve the semantics of attribute namespace prefixes during tokenization round-trips, which allows an attacker to craft inputs that behave in conflicting ways during different stages of processing in affected downstream applications.

Record
CVE-2020-29509
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
Updated
2026-11-02
EUVDEUVD-2022-1254 9.8

The encoding/xml package in Go (all versions) does not correctly preserve the semantics of attribute namespace prefixes during tokenization round-trips, which allows an attacker to craft inputs that behave in conflicting ways during different stages of processing in affected downstream applications.

Record
EUVD-2022-1254
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
2026-11-03
GitHub AdvisoriesGHSA-xhqq-x44f-9fgg 9.8

Authentication Bypass in github.com/russellhaering/gosaml2

Impact

Given a valid SAML Response, it may be possible for an attacker to mutate the XML document in such a way that gosaml2 will trust a different portion of the document than was signed.

Depending on the implementation of the Service Provider this enables a variety of attacks, including users accessing accounts other than the one to which they authenticated in the Identity Provider, or full authentication bypass.

Patches

Service Providers utilizing gosaml2 should upgrade to v0.6.0 or greater.

Record
GHSA-xhqq-x44f-9fgg
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
Updated
2026-11-02
NVD 9.8

The encoding/xml package in Go (all versions) does not correctly preserve the semantics of attribute namespace prefixes during tokenization round-trips, which allows an attacker to craft inputs that behave in conflicting ways during different stages of processing in affected downstream applications.

Record
CVE-2020-29509
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 3.1
5.6 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L
CVSS 2.0
6.8 MediumAV:N/AC:M/Au:N/C:P/I:P/A:P
Weakness
CWE-115
Updated
2026-11-02
OSVALPINE-CVE-2020-29509 5.6

The encoding/xml package in Go (all versions) does not correctly preserve the semantics of attribute namespace prefixes during tokenization round-trips, which allows an attacker to craft inputs that behave in conflicting ways during different stages of processing in affected downstream applications.

Record
ALPINE-CVE-2020-29509
CVSS 3.1
5.6 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L
Updated
2026-11-03
OSVAZL-6448 5.6

CVE-2020-29509 affecting package golang for versions less than 1.20.10-1

The encoding/xml package in Go (all versions) does not correctly preserve the semantics of attribute namespace prefixes during tokenization round-trips, which allows an attacker to craft inputs that behave in conflicting ways during different stages of processing in affected downstream applications.

Record
AZL-6448
CVSS 3.1
5.6 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L
Updated
2026-11-02
Show 9 moreShow less
OSVAZL-78900 5.6

CVE-2020-29509 affecting package golang 1.26.7-1

The encoding/xml package in Go (all versions) does not correctly preserve the semantics of attribute namespace prefixes during tokenization round-trips, which allows an attacker to craft inputs that behave in conflicting ways during different stages of processing in affected downstream applications.

Record
AZL-78900
CVSS 3.1
5.6 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L
Updated
2026-11-02
OSVBELL-CVE-2020-29509 5.6

CVE-2020-29509 does not affect BellSoft software

Record
BELL-CVE-2020-29509
CVSS 3.1
5.6 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L
Updated
2026-11-02
OSV 5.6

The encoding/xml package in Go (all versions) does not correctly preserve the semantics of attribute namespace prefixes during tokenization round-trips, which allows an attacker to craft inputs that behave in conflicting ways during different stages of processing in affected downstream applications.

Record
CVE-2020-29509
CVSS 3.1
5.6 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L
Updated
2026-11-02
OSVDEBIAN-CVE-2020-29509 5.6

The encoding/xml package in Go (all versions) does not correctly preserve the semantics of attribute namespace prefixes during tokenization round-trips, which allows an attacker to craft inputs that behave in conflicting ways during different stages of processing in affected downstream applications.

Record
DEBIAN-CVE-2020-29509
CVSS 3.1
5.6 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L
Updated
2026-11-02
OSVGHSA-xhqq-x44f-9fgg 9.8

Authentication Bypass in github.com/russellhaering/gosaml2

Impact

Given a valid SAML Response, it may be possible for an attacker to mutate the XML document in such a way that gosaml2 will trust a different portion of the document than was signed.

Depending on the implementation of the Service Provider this enables a variety of attacks, including users accessing accounts other than the one to which they authenticated in the Identity Provider, or full authentication bypass.

Patches

Service Providers utilizing gosaml2 should upgrade to v0.6.0 or greater.

Record
GHSA-xhqq-x44f-9fgg
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
Updated
2026-11-02
OSVOESA-2021-1011 5.6

golang security update

The Go Programming Language.\r\n\r\n Security Fix(es):\r\n\r\n The encoding/xml package in Go (all versions) does not correctly preserve the semantics of attribute namespace prefixes during tokenization round-trips, which allows an attacker to craft inputs that behave in conflicting ways during different stages of processing in affected downstream applications.(CVE-2020-29509)\r\n\r\n

Record
OESA-2021-1011
CVSS 3.1
5.6 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L
Updated
2026-11-02
OSVUBUNTU-CVE-2020-29509 9.8

The encoding/xml package in Go (all versions) does not correctly preserve the semantics of attribute namespace prefixes during tokenization round-trips, which allows an attacker to craft inputs that behave in conflicting ways during different stages of processing in affected downstream applications.

Record
UBUNTU-CVE-2020-29509
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 3.1
5.6 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L
Updated
2026-11-02
OSVBIT-golang-2020-29509 No score

The encoding/xml package in Go (all versions) does not correctly preserve the semantics of attribute namespace prefixes during tokenization round-trips, which allows an attacker to craft inputs that behave in conflicting ways during different stages of processing in affected downstream applications.

Record
BIT-golang-2020-29509
Updated
2026-11-02
OSVGO-2021-0060 No score

Authentication bypass in github.com/russellhaering/gosaml2

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-2021-0060
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
github.com/russellhaering/gosaml2
Go
 before 0.6.0
0.6.0
go
Alpine:v3.18
 before 1.17-r0
1.17-r0
go
Alpine:v3.19
 before 1.17-r0
1.17-r0
go
Alpine:v3.20
 before 1.17-r0
1.17-r0
go
Alpine:v3.21
 before 1.17-r0
1.17-r0
go
Alpine:v3.22
 before 1.17-r0
1.17-r0
go
Alpine:v3.23
 before 1.17-r0
1.17-r0
go
Alpine:v3.24
 before 1.17-r0
1.17-r0
golang
Azure Linux:2
 1.19.0 up to 1.20.10-1
1.20.10-1
golang
Azure Linux:3
 through 1.26.7-1 None known
Show 15 moreShow less
Affected packages
PackageAffectedFixed
golang
Bitnami
 before 1.17.0
1.17.0
golang-1.15
Debian:11
 All versions, plus listed versions
1.15.15-11.15.15-1~deb11u11.15.15-1~deb11u21.15.15-1~deb11u31.15.15-1~deb11u4
Show 5 moreShow less
1.15.15-21.15.15-31.15.15-41.15.15-51.15.9-6
 None known
golang
openEuler:20.03-LTS
 before 1.13.15-2.oe1
1.13.15-2.oe1
golang
openEuler:20.03-LTS-SP1
 before 1.13.15-2.oe1
1.13.15-2.oe1
golang-1.10
Ubuntu:14.04:LTS
 All versions, plus listed versions
1.10.4-2ubuntu1~14.04.1
 None known
golang-1.10
Ubuntu:16.04:LTS
 All versions, plus listed versions
1.10.4-2ubuntu1~16.04.11.10.4-2ubuntu1~16.04.2
 None known
golang-1.6
Ubuntu:16.04:LTS
 All versions, plus listed versions
1.6-0ubuntu11.6-0ubuntu21.6-0ubuntu31.6-0ubuntu41.6-0ubuntu5
Show 5 moreShow less
1.6.1-0ubuntu11.6.2-0ubuntu5~16.041.6.2-0ubuntu5~16.04.21.6.2-0ubuntu5~16.04.31.6.2-0ubuntu5~16.04.4
 None known
golang-1.13
Ubuntu:Pro:16.04:LTS
 All versions, plus listed versions
1.13.8-1ubuntu1~16.04.21.13.8-1ubuntu1~16.04.31.13.8-1ubuntu1~16.04.3+esm21.13.8-1ubuntu1~16.04.3+esm3
 None known
golang-1.10
Ubuntu:18.04:LTS
 All versions, plus listed versions
1.10~rc1-11.10~rc1-1ubuntu11.10~rc1-2ubuntu11.10~rc2-1ubuntu11.10-1ubuntu11.10.1-1ubuntu21.10.4-2ubuntu1~18.04.11.10.4-2ubuntu1~18.04.2
 None known
golang-1.13
Ubuntu:Pro:18.04:LTS
 All versions, plus listed versions
1.13.8-1ubuntu1~18.04.21.13.8-1ubuntu1~18.04.31.13.8-1ubuntu1~18.04.41.13.8-1ubuntu1~18.04.4+esm1
 None known
golang-1.8
Ubuntu:18.04:LTS
 All versions, plus listed versions
1.8.3-2ubuntu11.8.3-2ubuntu1.18.04.1
 None known
golang-1.9
Ubuntu:18.04:LTS
 All versions, plus listed versions
1.9.1-2ubuntu11.9.2-1ubuntu11.9.2-3ubuntu11.9.3-1ubuntu11.9.4-1ubuntu1
 None known
golang-1.13
Ubuntu:20.04:LTS
 All versions, plus listed versions
1.13.1-1ubuntu11.13.3-1ubuntu11.13.4-1ubuntu11.13.5-1ubuntu11.13.6-1ubuntu1
Show 5 moreShow less
1.13.6-2ubuntu11.13.7-1ubuntu11.13.8-1ubuntu11.13.8-1ubuntu1.11.13.8-1ubuntu1.2
 None known
golang-1.14
Ubuntu:20.04:LTS
 All versions, plus listed versions
1.14~beta1-11.14~beta1-21.14~rc1-11.14-11.14.1-1
Show 4 moreShow less
1.14.2-11.14.2-1ubuntu11.14.3-2ubuntu2~20.04.11.14.3-2ubuntu2~20.04.2
 None known
golang-1.13
Ubuntu:Pro:22.04:LTS
 All versions, plus listed versions
1.13.8-1ubuntu21.13.8-1ubuntu2.22.04.11.13.8-1ubuntu2.22.04.1+esm11.13.8-1ubuntu2.22.04.2
 None known

History

History
RecordedChangedSources
affected, aliases, referencesOSV
aliases, products, publishedEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

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

In short

CVE-2020-29509 is a critical vulnerability (CVSS 9.8) in Ecies Go, published December 14, 2020. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 2.10%, the 81st percentile. Fixed in github.com/russellhaering/gosaml2 0.6.0.

References

Show 8 moreShow less
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