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CVE Record

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...

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.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This flaw can let a remote party crash some Go-based HTTP software by sending an unusually large header. The impact is denial of service, not data theft or code execution based on the provided sources. Priority depends on whether exposed services or clients were built with vulnerable Go versions.

Executive priority

Treat this as a moderate availability risk. It is most important for public-facing Go HTTP systems where a crash could disrupt customer access or operations. No source provided evidence of active exploitation or data compromise.

Technical view

Go net/http before 1.15.12 and 1.16.x before 1.16.4 could panic when ReadRequest or ReadResponse handled a large header. The CVE states Server, Transport, and Client may be affected in some configurations. Public data does not provide CVSS, CWE, or detailed configuration prerequisites.

Likely exposure

Exposure is most likely in internet-facing or untrusted-network Go HTTP servers, clients, transports, or products compiled with affected Go releases. Embedded vendor products may remain exposed until rebuilt, even if source dependencies look current.

Exploitation context

The source bundle does not show CISA KEV listing or cited evidence of active exploitation. The described attack condition is remote denial of service through oversized HTTP header handling in affected net/http paths.

Researcher notes

Scope should be configuration-specific. The CVE text is broad and lacks CVSS/CWE detail, so confirm affected code paths against the Go issue and release announcement. Avoid assuming all Go software is vulnerable without build-version and net/http usage evidence.

Mitigation direction

  • Upgrade Go to 1.15.12, 1.16.4, or later supported releases.
  • Rebuild and redeploy affected Go binaries after updating the toolchain.
  • Check Fedora, Gentoo, and vendor package advisories for patched builds.
  • Ask vendors whether embedded Go components were rebuilt with fixed Go versions.
  • Prioritize exposed HTTP services and high-availability systems first.

Validation and detection

  • Inventory services and products built with Go before 1.15.12 or 1.16.4.
  • Confirm production binaries were rebuilt after the fixed Go release was applied.
  • Review whether applications use net/http Server, Transport, Client, ReadRequest, or ReadResponse.
  • Check logs and crash reports for unexplained HTTP header-related panics.
  • Verify distribution package versions against Fedora, Gentoo, or vendor advisories.
Prepared
Confidence
medium
Sources
6

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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CVE-2021-31525 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
5Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/an/an/aListed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.