CVE-2021-36221

Go before 1.15.15 and 1.16.x before 1.16.7 has a race condition that can lead to a net/http/httputil ReverseProxy panic upon an ErrAbortHandler abort.

Published: 2021-08-08 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-36221 is rated Moderate Risk (56.7/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 3.13%). EPSS rose +2.93% over the last day, indicating growing attacker interest. Review affected assets and schedule 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-2021-36221

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 0.20% 3.13% +2.93%
2 2025-11-21 2.31% 0.20% -2.11%
3 2025-11-18 — 2.31% —

Full EPSS history (25 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-36221

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.9 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/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: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:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.2 3.6 [email protected]
4.3 2.0 MEDIUM
AV:N/AC:M/Au:N/C:N/I:N/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:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 8.6 2.9 [email protected]

Weakness enumeration for CVE-2021-36221

OS Trackers for CVE-2021-36221

vendor priority summary link
alpine medium CVE-2021-36221: 1 source package rows (go); 37 state rows across 7 repos (3.17-community, 3.18-community, 3.19-community, 3.20-community, 3.21-community, 3.22-community, edge-community); fixed 7, open 30. https://security.alpinelinux.org/vuln/CVE-2021-36221
debian not yet assigned CVE-2021-36221 not yet assigned priority: Debian including 1 source packages (golang-1.15), 1 status rows across 1 suites (bullseye): resolved 1. https://security-tracker.debian.org/tracker/CVE-2021-36221
gentoo high CVE-2021-36221: 1 GLSA(s) (202208-02), 1 atom(s) (dev-lang/go); latest impact high. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-36221
redhat medium — https://access.redhat.com/security/cve/CVE-2021-36221
ubuntu medium CVE-2021-36221 medium priority: Ubuntu including 9 source packages (golang, golang-1.10, …), 127 status rows across 15 suites (bionic, focal, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 96, needs-triage 22, ignored 9. https://ubuntu.com/security/CVE-2021-36221

Affected software / configurations for CVE-2021-36221

Vendor Product Version Raw CPE
golang go < 1.15.15 cpe:2.3:a:golang:go:*:*:*:*:*:*:*:*
golang go >= 1.16.0, < 1.16.7 cpe:2.3:a:golang:go:*:*:*:*:*:*:*:*
fedoraproject fedora 33 cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
fedoraproject fedora 34 cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
fedoraproject fedora 35 cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:*
debian debian_linux 9.0 cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
oracle timesten_in-memory_database < 21.1.1.1.0 cpe:2.3:a:oracle:timesten_in-memory_database:*:*:*:*:*:*:*:*
siemens scalance_lpe9403_firmware < 2.0 cpe:2.3:o:siemens:scalance_lpe9403_firmware:*:*:*:*:*:*:*:*

References for CVE-2021-36221

URL Tags
https://cert-portal.siemens.com/productcert/pdf/ssa-222547.pdf Patch Third Party Advisory
https://groups.google.com/forum/#%21forum/golang-announce
https://groups.google.com/g/golang-announce/c/JvWG9FUUYT0 Mailing List Third Party Advisory
https://groups.google.com/g/golang-announce/c/uHACNfXAZqk Mailing List Third Party Advisory
https://lists.debian.org/debian-lts-announce/2022/01/msg00016.html Mailing List Third Party Advisory
https://lists.debian.org/debian-lts-announce/2022/01/msg00017.html Mailing List Third Party Advisory
https://lists.debian.org/debian-lts-announce/2023/04/msg00021.html
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2MU47VKTNXX33ZDLTI2ORRUY3KLJKU6G/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HM7U5JNS5WU66Q3S26PFIU2ITB2ATTQ4/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/J4AMYYHGBYMIWCCR5RCDFI5RAUJOPO5L/
https://security.gentoo.org/glsa/202208-02 Third Party Advisory
https://www.oracle.com/security-alerts/cpujan2022.html Third Party Advisory
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