CVE-2021-34558

The crypto/tls package of Go through 1.16.5 does not properly assert that the type of public key in an X.509 certificate matches the expected type when doing a RSA based key exchange, allowing a malicious TLS server to cause a TLS client to panic.

Published: 2021-07-15 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-34558 is rated Moderate Risk (63.7/100): CVSS Medium severity, with high exploitation likelihood (EPSS 7.03%, 93th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. EPSS rose +6.11% 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-2021-34558

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 0.92% 7.03% +6.11%
2 2026-04-03 1.47% 0.92% -0.56%
3 2026-01-28 — 1.47% —

Full EPSS history (29 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-34558

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/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: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:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
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.
 2.8 3.6 [email protected]
2.6 2.0 LOW
AV:N/AC:H/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:H)
Exploitation requires uncommon or highly specific conditions.
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.
 4.9 2.9 [email protected]

Weakness enumeration for CVE-2021-34558

OS Trackers for CVE-2021-34558

vendor priority summary link
alpine medium CVE-2021-34558: 1 source package rows (go); 35 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 28. https://security.alpinelinux.org/vuln/CVE-2021-34558
debian not yet assigned CVE-2021-34558 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-2021-34558
gentoo high CVE-2021-34558: 1 GLSA(s) (202208-02), 1 atom(s) (dev-lang/go); latest impact high. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-34558
redhat medium — https://access.redhat.com/security/cve/CVE-2021-34558
suse medium CVE-2021-34558 severity moderate: SUSE including 70 source package names (1.0.1-build4.16.1:go1.16-1.16.6-1.20.1, 1.16-13.3:go1.16-1.16.6-1.20.1, …), 106 product×package rows across 13 product lines (Container bci/golang, Container trento/trento-runner, … (13 product lines)): Fixed 106. https://www.suse.com/security/cve/CVE-2021-34558/
ubuntu medium CVE-2021-34558 medium priority: Ubuntu including 9 source packages (golang, golang-1.10, …), 136 status rows across 16 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 102, needs-triage 22, ignored 12. https://ubuntu.com/security/CVE-2021-34558

Affected software / configurations for CVE-2021-34558

Vendor Product Version Raw CPE
golang go < 1.15.14 cpe:2.3:a:golang:go:*:*:*:*:*:*:*:*
golang go >= 1.16.0, < 1.16.6 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:*:*:*:*:*:*:*
netapp cloud_insights_telegraf — cpe:2.3:a:netapp:cloud_insights_telegraf:-:*:*:*:*:*:*:*
netapp storagegrid — cpe:2.3:a:netapp:storagegrid:-:*:*:*:*:*:*:*
netapp trident — cpe:2.3:a:netapp:trident:-:*:*:*:*:*:*:*
oracle timesten_in-memory_database < 21.1.1.1.0 cpe:2.3:a:oracle:timesten_in-memory_database:*:*:*:*:*:*:*:*

References for CVE-2021-34558

URL Tags
https://golang.org/doc/devel/release#go1.16.minor Release Notes Vendor Advisory
https://groups.google.com/g/golang-announce Mailing List Third Party Advisory
https://groups.google.com/g/golang-announce/c/n9FxMelZGAQ Mailing List Release Notes Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3BA7MFVXRBEKRTLSLYDICTYCGEMK2HZ7/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3XBQUFVI5TMV4KMKI7GKA223LHGPQISE/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/6BTC3JQUASFN5U2XA4UZIGAPZQBD5JSS/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/D7FRFM7WWR2JCT6NORQ7AO6B453OMI3I/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ITRXPCHUCJGXCX2CUEPKZRRTB27GG4ZB/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JYIUSR4YP52PWG7YE7AA3DZ5OSURNFJB/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LBMLUQMN6XRKPVOI5XFFBP4XSR7RNTYR/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NLOGBB7XBBRB3J5FDPW5KWHSH7IRF64W/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WXJ2MVMAHOIGRH37ZSFYC4EVWLJFL2EQ/
https://security.gentoo.org/glsa/202208-02 Third Party Advisory
https://security.netapp.com/advisory/ntap-20210813-0005/ Third Party Advisory
https://www.oracle.com/security-alerts/cpujan2022.html Patch Third Party Advisory
https://www.oracle.com/security-alerts/cpuoct2021.html Patch Third Party Advisory
cvelogic Threat Intelligence