Quick answers
- Is CVE-2026-56858 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-56858 being exploited in the wild.
- How severe is CVE-2026-56858?
- Medium severity, with a CVSS score of 6.1, 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-2026-56858?
- 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-2026-56858 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-56858?
- 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 is a path traversal/injection flaw in Go's path handling logic where pathological inputs containing unescaped forward slashes can prematurely close path segments, allowing attacker-controlled data to inject arbitrary content. The root cause involves insufficient escaping or validation of forward slash characters in path processing. The attack is network-reachable and does not require authentication, though it depends on the affected application processing user-supplied paths. An attacker can achieve XSS or other injection attacks by crafting malicious path inputs. A patch has been committed (referenced in CL 807100).
Affected products
- Go Go
Identifiers
- CVE-2026-56858
- GO-2026-6091
Timeline
- 2026-08-13: disclosed
- other: CVE-2026-56858 assigned