# CVE-2026-122130: CESNET ipfixcol2 2.3.0 before 2.9.0 Buffer Overflow via Forwarder Output Plugin

Status: published. Published: 2026-11-04. Updated: 2026-11-04.

CESNET ipfixcol2 2.3.0 before 2.9.0 contains an integer overflow vulnerability in the Forwarder output plugin that allows unauthenticated IPFIX exporters to overflow a heap buffer by wrapping uint16_t message length counters. Attackers can send near-65535-byte data sets and large templates to a collector forwarding over TCP to crash it and perform 2-byte writes to attacker-influenced addresses.

## Remediation

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: VulnCheck) — https://github.com/CESNET/ipfixcol2/commit/ad206f6217257b06b139f1b2bce50d52f5bc6acb

## Affected products and versions

- CESNET / ipfixcol2: ≥ 2.3.0; < 2.9.0 (affected, semver). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 8.3 (high); CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N; source: CNA: VulnCheck

- CVSS 3.1: 8.2 (high); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H; source: CNA: VulnCheck

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-190

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/CESNET/ipfixcol2/commit/ad206f6217257b06b139f1b2bce50d52f5bc6acb (CNA: VulnCheck; patch)

- https://github.com/CESNET/ipfixcol2 (CNA: VulnCheck; product)

- https://github.com/CESNET/ipfixcol2/releases/tag/v2.9.0 (CNA: VulnCheck; release-notes)

- https://github.com/CESNET/ipfixcol2/blob/v2.8.0/src/plugins/output/forwarder/src/Message.cpp#L134-L156 (CNA: VulnCheck; technical-description)

- https://www.vulncheck.com/advisories/cesnet-ipfixcol2-2.3.0-before-2.9.0-buffer-overflow-via-forwarder-output-plugin (CNA: VulnCheck; third-party-advisory)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-122130; retrieved 2026-11-04; source updated 2026-11-04

Revision: 7262f994e48b8f83c07e67b6a5c1532182b6841e2ce4a0837f35d2a35e243ab6

Canonical: https://y2.dev/cve/CVE-2026-122130

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