What is CVE-2026-93894?

CVE-2026-93894 is In Vinyl Cache before 9.0,2, workspace buffer overflow vulnerability was found in the .upper() and .lower() string type methods of VCL. The supplied enrichment data classifies it as Memory Corruption mapped to CWE-787 Out-of-bounds Write.

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-2026-93894. If exploitation is not confirmed from current sources, teams should document that status and continue monitoring KEV, vendor, and telemetry updates.

No. CVE-2026-93894 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-2026-93894. Public exploit or PoC availability should raise triage priority, especially for exposed or business-critical systems.

How can defenders detect it?

Start with web/proxy/WAF logs, application logs, network IDS/IPS 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-2026-93894 using CVSS 2.3, EPSS 0%, KEV status, public PoC status, and asset exposure. Internet-facing, privileged, or business-critical deployments should be handled first.

Are workarounds available?

Workarounds are not confirmed from current sources. 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.

lowMemory Corruption

CVE-2026-93894

CVE-2026-93894 — In Vinyl Cache before 9.0,2, workspace buffer overflow vulnerability was found in the .upper() and .lower() string type methods of VCL

In Vinyl Cache before 9.0,2, workspace buffer overflow vulnerability was found in the .upper() and .lower() string type methods of VCL. This can be used as a remote denial of service (DoS) vector to make the child process segfault or assert, and then restart. Effectively exploiting this vulnerability requires prior knowledge about the VCL in use and the ability to craft a request that contains a string that is long enough to fill the remaining workspace at the call site while staying under the different request size limits (http_req_size, http_req_hdr_len, etc.).

Published Sep 18, 2026Updated Sep 18, 2026Sources: NVD, Vinyl-Cache (CNA), GitHub, GitHub Security Advisory, 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

Vinyl-Cache

5 products listed

CVSS base

2.3

low

Remediation

The vendor's own words where we have them.

Update to unaffected Version

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
Vinyl-Cache	Vinyl Cache	0 to < 9.0.2	Vulnerable
Vinyl-Cache	Vinyl Cache	0 to < 90f5bacc14b2404e6cc349ba015f0f73b8515136	Vulnerable
Varnish-Software	Varnish Cache	9.0.0 to < 9.0.4	Vulnerable
Varnish-Software	Varnish Cache	0	Vulnerable
Varnish-Software	Varnish Cache	6.3.0 to <= 8.0.2	Vulnerable

Attack characteristics

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

Attack Complexity

High

Attack Vector

Network

Privileges Req

Low

User Interaction

None

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
2.3	CVSS 4.0	low	—	—	Vinyl-Cache (CNA)

CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/AU:N/R:A/V:D/RE:L/U:Clear

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-787 · Out-of-bounds Write

Modify Memory
DoS: Crash, Exit, or Restart
Execute Unauthorized Code or Commands::

Mitigation: Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.

Weakness & attack patterns

CWE-787Out-of-bounds Write

Inferred from the weakness class — not observed against this CVE.

CAPEC-100 · Overflow BuffersCAPEC-123 · Buffer Manipulation

Detection

Read off the CVSS vector and the weakness class. Starting points, not rules we have tested.

Prioritize edge telemetry for network-reachable Vinyl Cache, Varnish Cache.

web/proxy/WAF logsapplication logsnetwork IDS/IPS

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 2.3 (AV:N)
Sep 18, 2026 · NVD
Initial · CVE published
Sep 18, 2026 · NVD
Added · GHSA-pfj3-384h-g8q8 published (low)
Sep 18, 2026 · GitHub Security Advisory
CVE published by MITRE.
Sep 18, 2026 · SOCRadar CTI

References

3 on the record

vinyl-cache.org/security/VSV00020.html
Vendor Advisory
nvd.nist.gov/vuln/detail/CVE-2026-93894
NVD
github.com/advisories/GHSA-pfj3-384h-g8q8
Exploit, Third Party Advisory

Elsewhere on this site

Vinyl-Cacheevery CVE for this vendor
Varnish-Softwareevery CVE for this vendor
Memory Corruptionsame class
CWE-787other 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-2026-93894 is In Vinyl Cache before 9.0,2, workspace buffer overflow vulnerability was found in the .upper() and .lower() string type methods of VCL, a low vulnerability affecting Vinyl Cache, Varnish Cache from Vinyl-Cache, Varnish-Software. 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-2026-93894. Public exploit evidence is: A public PoC is not confirmed from current sources for CVE-2026-93894. 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 2.3 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.