How severe is CVE-2021-31525?

CVE-2021-31525 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-31525 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (88th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-31525?

CVE-2021-31525 primarily affects Golang Go. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-31525?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-31525 published?

CVE-2021-31525 was published on 2021-05-27 and last updated on 2026-06-17.

CVE-2021-31525

CVE-2021-31525 is a medium-severity vulnerability in Golang Go with a CVSS 3.x base score of 5.9. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-674.

Key facts

Severity: Medium (CVSS 3.x base score 5.9)
CVSS v2: 2.6
EPSS exploit prediction: 4% (88th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-674
Affected product: Golang Go
Published: 2021-05-27
Last modified: 2026-06-17

Description

net/http in Go before 1.15.12 and 1.16.x before 1.16.4 allows remote attackers to cause a denial of service (panic) via a large header to ReadRequest or ReadResponse. Server, Transport, and Client can each be affected in some configurations.

Frequently asked questions

What is CVE-2021-31525?: net/http in Go before 1.15.12 and 1.16.x before 1.16.4 allows remote attackers to cause a denial of service (panic) via a large header to ReadRequest or ReadResponse. Server, Transport, and Client can each be affected in some configurations.
How severe is CVE-2021-31525?: CVE-2021-31525 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-31525 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (88th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-31525?: CVE-2021-31525 primarily affects Golang Go. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-31525?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-31525 published?: CVE-2021-31525 was published on 2021-05-27 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:a:golang:go:*:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*

More vulnerabilities in Golang Go

CVE-2025-68121 — Critical (CVSS 10.0): During session resumption in crypto/tls, if the underlying Config has its ClientCAs or RootCAs fields mutated between…
CVE-2026-27143 — Critical (CVSS 9.8): Arithmetic over induction variables in loops were not correctly checked for underflow or overflow. As a result, the…
CVE-2024-24790 — Critical (CVSS 9.8): The various Is methods (IsPrivate, IsLoopback, etc) did not work as expected for IPv4-mapped IPv6 addresses, returning…
CVE-2023-39320 — Critical (CVSS 9.8): The go.mod toolchain directive, introduced in Go 1.21, can be leveraged to execute scripts and binaries relative to the…
CVE-2023-29405 — Critical (CVSS 9.8): The go command may execute arbitrary code at build time when using cgo. This may occur when running "go get" on a…
CVE-2023-29404 — Critical (CVSS 9.8): The go command may execute arbitrary code at build time when using cgo. This may occur when running "go get" on a…

All CVEs affecting Golang Go →

Other CWE-674 (Uncontrolled Recursion) vulnerabilities

CVE-2026-43185 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix signededness bug in…
CVE-2023-51803 — Critical (CVSS 9.8): LinuxServer.io Heimdall before 2.5.7 does not prevent use of icons that have non-image data such as the "<?php ?>"…
CVE-2021-41752 — Critical (CVSS 9.8): Stack overflow vulnerability in Jerryscript before commit e1ce7dd7271288be8c0c8136eea9107df73a8ce2 on Oct 20, 2021 due…
CVE-2018-1000618 — Critical (CVSS 9.8): EOSIO/eos eos version after commit f1545dd0ae2b77580c2236fdb70ae7138d2c7168 contains a stack overflow vulnerability in…
CVE-2025-10728 — Critical (CVSS 9.4): When the module renders a Svg file that contains a <pattern> element, it might end up rendering it recursively leading…
CVE-2026-40324 — Critical (CVSS 9.1): Hot Chocolate is an open-source GraphQL server. Prior to versions 12.22.7, 13.9.16, 14.3.1, and 15.1.14, Hot…

Browse all CWE-674 (Uncontrolled Recursion) vulnerabilities →