CVE-2020-29509

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.

Published: 2020-12-14 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2020-29509 is rated High Risk (68.7/100): CVSS Critical severity, with medium exploitation likelihood (EPSS 2.08%). EPSS rose +1.89% over the last day, indicating growing attacker interest. High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2020-29509

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.19% 2.08% +1.89%
2 2025-11-21 0.40% 0.19% -0.22%
3 2025-11-18 — 0.40% —

Full EPSS history (12 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2020-29509

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]
5.6 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 2.2 3.4 [email protected]
6.8 2.0 MEDIUM
AV:N/AC:M/Au:N/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 8.6 6.4 [email protected]

Weakness enumeration for CVE-2020-29509

GitHub Security Advisory for CVE-2020-29509

GHSA-xhqq-x44f-9fgg · Severity: critical · Ecosystem: go — Authentication Bypass in github.com/russellhaering/gosaml2

OS Trackers for CVE-2020-29509

vendor priority summary link
alpine medium CVE-2020-29509: 1 source package rows (go); 188 state rows across 8 repos (3.17-community, 3.18-community, 3.19-community, 3.20-community, 3.21-community, 3.22-community, 3.23-community, edge-community); fixed 151, open 37. https://security.alpinelinux.org/vuln/CVE-2020-29509
debian unimportant CVE-2020-29509 unimportant priority: Debian including 1 source packages (golang-1.15), 1 status rows across 1 suites (bullseye): open 1. https://security-tracker.debian.org/tracker/CVE-2020-29509
redhat low — https://access.redhat.com/security/cve/CVE-2020-29509
suse high — https://www.suse.com/security/cve/CVE-2020-29509/
ubuntu medium CVE-2020-29509 medium priority: Ubuntu including 8 source packages (golang, golang-1.10, …), 120 status rows across 16 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 92, deferred 11, ignored 9, needs-triage 8. https://ubuntu.com/security/CVE-2020-29509

Affected software / configurations for CVE-2020-29509

Vendor Product Version Raw CPE
golang go < 1.17 cpe:2.3:a:golang:go:*:*:*:*:*:*:*:*
netapp trident — cpe:2.3:a:netapp:trident:-:*:*:*:*:*:*:*

References for CVE-2020-29509

cvelogic Threat Intelligence