Is CVE-2026-56860 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-56860 being exploited in the wild.

How severe is CVE-2026-56860?

Medium severity, with a CVSS score of 5.9, published 13 August 2026.

Which products and versions are affected?

stdlib (Go) SEMVER:introduced=0,fixed=1.25.13,introduced=1.26.0-0,fixed=1.26.6,introduced=1.27.0-0,fixed=1.27.0-rc.3.

Is there a fix for CVE-2026-56860?

Yes. stdlib (Go): upgrade to 1.27.0-rc.3 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-56860 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-56860?

Check whether you run stdlib (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-56860: Go path resolution denial of service via parent directory segments

CVE-2026-56860 · Severity: medium · CVSS 5.9 · Published 2026-08-13

Go's path resolution function suffered from inefficient handling of relative paths containing parent directory ("..") segments, causing excessive memory allocation and processing time. An attacker could craft malicious paths to trigger a denial-of-service condition by exhausting system resources or significantly slowing application performance.

Technologies: stdlib (Go). Vendors: Go.

Quick answers

Is CVE-2026-56860 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-56860 being exploited in the wild.
How severe is CVE-2026-56860?: Medium severity, with a CVSS score of 5.9, published 13 August 2026.
Which products and versions are affected?: stdlib (Go) SEMVER:introduced=0,fixed=1.25.13,introduced=1.26.0-0,fixed=1.26.6,introduced=1.27.0-0,fixed=1.27.0-rc.3.
Is there a fix for CVE-2026-56860?: Yes. stdlib (Go): upgrade to 1.27.0-rc.3 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-56860 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-56860?: Check whether you run stdlib (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

stdlib (Go): upgrade to 1.27.0-rc.3 or later
```
go get stdlib@v1.27.0-rc.3
```

Technical details

The vulnerability exists in Go's path resolution logic, which previously performed string conversions and buffer rewrites on each parent directory ("..") segment, resulting in quadratic time complexity and excessive memory overhead. An attacker can exploit this by providing relative paths with many ".." segments to cause high CPU and memory consumption. The attack requires no authentication and is network-reachable if the affected path resolution is exposed through a network service. The fix replaces the inefficient string-based approach with index-based backtracking on a byte buffer, eliminating the quadratic complexity and reducing memory allocations.

Affected products

Go Go

Identifiers

CVE-2026-56860
GO-2026-6218

Timeline

2026-08-13: disclosed

References

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