No exploitation reportedFix available

CVE-2021-27918

Q: Is CVE-2021-27918 actively exploited?

Active exploitation of CVE-2021-27918 has not been confirmed. Its EPSS score was 2.5% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2021-27918?

CVE-2021-27918 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

No exploitation reported by the sources we read.

Published2021-03-11
Fixed in1.16.1 · 1.15.9
WeaknessCWE-835

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

encoding/xml in Go before 1.15.9 and 1.16.x before 1.16.1 has an infinite loop if a custom TokenReader (for xml.NewTokenDecoder) returns EOF in the middle of an element. This can occur in the Decode, DecodeElement, or Skip method.

Timeline

dates in UTC

2021-03-1100:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-27918?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-27918?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Branch	Affected	Fixed in	Source
1.16	≥ 1.16.0, < 1.16.1	1.16.1	NVD
1.15	< 1.15.9	1.15.9	NVD

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Update Go to 1.16.1 · 1.15.9

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

NVDCVSS 3.17.5read 2026-10-23
NVDCVSS 2.05read 2026-10-23
NVDweakness (CWE)CWE-835read 2026-10-23
FIRST EPSSEPSS score2.5 %2026-10-22

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published: 2021-03-11
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2021-27918?

Is CVE-2021-27918 actively exploited?

Active exploitation of CVE-2021-27918 has not been confirmed. Its EPSS score was 2.5% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-27918?

CVE-2021-27918 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

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