What is CVE-2026-82455?

CVE-2026-82455 is RubyGems before 4.0.13 Path Traversal via Symlink Resolution. The supplied enrichment data classifies it as Path Traversal mapped to CWE-59 Link Following.

Which versions are affected?

Affected product and version evidence is listed in the product table above. Current public advisories should be checked for exact version scope before patch targeting is finalized.

Is there active exploitation?

Active exploitation is not confirmed from current sources for CVE-2026-82455. If exploitation is not confirmed from current sources, teams should document that status and continue monitoring KEV, vendor, and telemetry updates.

No. CVE-2026-82455 is not listed in CISA KEV in the supplied enrichment data. KEV status should be monitored because it can change after initial disclosure or after exploitation becomes publicly confirmed.

Is there a public exploit?

A public PoC is not confirmed from current sources for CVE-2026-82455. Public exploit or PoC availability should raise triage priority, especially for exposed or business-critical systems.

How can defenders detect it?

Start with Not reported where available. Look for vulnerability-class behavior, product errors, suspicious authentication events, exploit probes, and abnormal process activity based only on evidence that applies to the affected product.

How should teams prioritize it?

Prioritize CVE-2026-82455 using CVSS 7.1, EPSS 0%, KEV status, public PoC status, and asset exposure. Internet-facing, privileged, or business-critical deployments should be handled first.

Are workarounds available?

The supplied mitigation guidance says to apply vendor patches and restrict external exposure until fixed. Fixed-version evidence is listed in the mitigation section above.

Which threat actors are linked publicly?

No public threat actor linkage is confirmed from current sources. Do not attribute exploitation to a threat actor unless the source evidence explicitly supports that linkage.

What should be done in the next 24 hours?

Identify exposed assets running affected vendor/product/version combinations. Prioritize based on EPSS, PoC availability, and external exposure. Search available logs for exploit probes, errors, authentication anomalies, or suspicious child processes matching the vulnerability class. Open remediation tickets with affected assets, owners, evidence status, and detection coverage so decisions are traceable.

highPath Traversal

CVE-2026-82455

CVE-2026-82455 — RubyGems before 4.0.13 Path Traversal via Symlink Resolution

RubyGems fails to re-validate path containment after filesystem symlink resolution during gem extraction. When a pre-existing symlink inside the destination directory points outside the extraction root, extracted files that appear to be written under the destination directory can instead be written outside of it, breaking the extraction safety boundary. The fix resolves the real path of the parent directory before writing and raises Gem::Package::PathError if it escapes the destination directory.

Published Aug 29, 2026Updated Aug 29, 2026Sources: NVD, ruby (CNA), SOCRadar CTI

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the scoring sources call it.

Exploitation

Unreported

no source claims exploitation

EPSS

ahead of 0% of scored CVEs

Affects

ruby

rubygems

CVSS base

7.1

high · 2 sources

Remediation

The vendor's own words where we have them.

Upgrade rubygems to a fixed release. Apply vendor patches per advisory and restrict external exposure of the affected component until patched.

First 24 hours

Ordered from the record's own fields — exposure first, because you cannot patch what you have not found.

Identify exposed assets running affected vendor/product/version combinations.
Prioritize based on EPSS, PoC availability, and external exposure.
Search available logs for exploit probes, errors, authentication anomalies, or suspicious child processes matching the vulnerability class.

Affected scope

Vendor, product and version as the advisories word them.

Vendor	Product	Versions	Status
ruby	rubygems	3.2.30 to < 4.0.13	Vulnerable

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Availability

High

Confidentiality

None

Integrity

High

Scope

Unchanged

Attack Complexity

Low

Attack Vector

Local

Privileges Req

None

User Interaction

Required

Every base score collected

Sources score independently and disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Source
7.1	CVSS 3.1	high	1.8	5.2	NVD, ruby (CNA)
6.9	CVSS 4.0	medium	—	—	ruby (CNA)

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H

What this weakness leads to

MITRE's own consequences and mitigations for the weakness class — the authority's wording, not guidance derived from the CVSS vector.

MITRE

CWE-59 · Improper Link Resolution Before File Access ('Link Following')

Read Files or Directories
Modify Files or Directories
Bypass Protection Mechanism
Execute Unauthorized Code or Commands

Mitigation: Follow the principle of least privilege when assigning access rights to entities in a software system. Denying access to a file can prevent an attacker from replacing that file with a link to a sensitive file. Ensure good compartmentalization in the system to provide protected areas that can be trusted.::

Weakness & attack patterns

CWE-59Link Following

Attack patterns reported against this CVE. The ATT&CK techniques below are inferred from its weakness class.

CAPEC-132 · Symlink AttackCAPEC-17 · Using Malicious FilesCAPEC-76 · Manipulating Web Input to File System CallsCAPEC-35 · Leverage Executable Code in Non-Executable Files

T1547.009Boot or Logon Autostart Execution: Shortcut Modification
T1574.005Hijack Execution Flow: Executable Installer File Permissions Weakness
T1574.010Hijack Execution Flow: Services File Permissions Weakness

Timeline

What happened to this CVE, newest first — with the readings a source repeats on a schedule counted underneath rather than listed.

2026
Added · CVSS 3.1 7.1 (AV:L)
Aug 29, 2026 · NVD
Initial · CVE published
Aug 29, 2026 · NVD
CVE published by MITRE.
Aug 29, 2026 · SOCRadar CTI

References

4 on the record

github.com/ruby/rubygems
Exploit, Third Party Advisory
github.com/ruby/rubygems/commit/103ca4230deacb31b9fcd813de109e83b5fc71ac
Exploit, Third Party Advisory, Mitre
github.com/ruby/rubygems/pull/9493
Exploit, Third Party Advisory, Mitre
www.vulncheck.com/advisories/rubygems-before-4.0.13-path-traversal-via-symlink-resolution
Vendor Advisory, Mitre

Elsewhere on this site

rubyevery CVE for this vendor
Path Traversalsame class
CWE-59other pages naming this weakness

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record1

What should defenders know first?

CVE-2026-82455 is RubyGems before 4.0.13 Path Traversal via Symlink Resolution, a high vulnerability affecting rubygems from ruby. The current evidence does not list it in CISA KEV, and the exploit status is: Active exploitation is not confirmed from current sources for CVE-2026-82455. Public exploit evidence is: A public PoC is not confirmed from current sources for CVE-2026-82455. The affected-version evidence is listed in the key facts and affected products tables. Defenders should first verify whether exposed or business-critical assets run those versions, then apply vendor patches or mitigations, restrict reachable attack surface, and preserve logs for detection review. CVSS 7.1 describes technical severity, while EPSS 0% helps estimate near-term exploit likelihood; neither replaces asset context. Unknown fields should remain explicit in tickets, and threat actor, IOC, victimology, or payload claims should not be added unless a cited source supports them. Monitor CISA KEV, vendor advisories, NVD changes, public PoC repositories, and internal telemetry for update triggers.