# CVE-2026-21620: TFTP Path Traversal

Status: published. Published: 2026-02-20. Updated: 2026-11-11.

Relative Path Traversal, Improper Isolation or Compartmentalization vulnerability in erlang otp erlang/otp (tftp_file modules), erlang otp inets (tftp_file modules), erlang otp tftp (tftp_file modules) allows Relative Path Traversal.

This vulnerability is associated with program files lib/tftp/src/tftp_file.erl, src/tftp_file.erl.

This issue affects OTP from OTP 17.0 before OTP 26.2.5.17, OTP 27.3.4.8, and OTP 28.3.2, corresponding to inets from 5.10 before 7.0, and tftp from 1.0 before 1.1.1.1, 1.2.2.1, and 1.2.4.

## Remediation

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: EEF) — https://github.com/erlang/otp/pull/10706
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: EEF) — https://github.com/erlang/otp/commit/655fb95725ba2fb811740b57e106873833824344
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: EEF) — https://github.com/erlang/otp/commit/3970738f687325138eb75f798054fa8960ac354e
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: EEF) — https://github.com/erlang/otp/commit/696fdec922661d4a3cc528fc34bc24fae8d4ad8a

## Affected products and versions

- Erlang / OTP (otp): ≥ 17.0; < * (affected, otp); unaffected at 26.2.5.17; unaffected at 27.3.4.8; unaffected at 28.3.2. Source: CNA: EEF
- Erlang / OTP (inets): ≥ 5.10; < 7.0 (affected, otp). Source: CNA: EEF
- Erlang / OTP (tftp): ≥ 1.0; < * (affected, otp); unaffected at 1.1.1.1; unaffected at 1.2.2.1; unaffected at 1.2.4. Source: CNA: EEF
- Erlang / OTP (erlang/otp): ≥ 07b8f441ca711f9812fad9e9115bab3c3aa92f79; < * (affected, git); unaffected at 655fb95725ba2fb811740b57e106873833824344; unaffected at 3970738f687325138eb75f798054fa8960ac354e; unaffected at 696fdec922661d4a3cc528fc34bc24fae8d4ad8a. Source: CNA: EEF

## Severity and prioritization

- CVSS 4.0: 2.3 (low); CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N; source: CNA: EEF

- CISA KEV: No listing in collected sources

- EPSS: 0.52% as of 2026-11-10; percentile 44.48%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-23

## Exploit evidence

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

## References

- https://github.com/erlang/otp/security/advisories/GHSA-hmrc-prh3-rpvp (CNA: EEF; vendor-advisory, related)

- https://cna.erlef.org/cves/CVE-2026-21620.html (CNA: EEF; related)

- https://osv.dev/vulnerability/EEF-CVE-2026-21620 (CNA: EEF; related)

- https://www.erlang.org/doc/system/versions.html#order-of-versions (CNA: EEF; x_version-scheme)

- https://github.com/erlang/otp/pull/10706 (CNA: EEF; patch)

- https://github.com/erlang/otp/commit/07b8f441ca711f9812fad9e9115bab3c3aa92f79 (CNA: EEF; related)

- https://github.com/erlang/otp/commit/655fb95725ba2fb811740b57e106873833824344 (CNA: EEF; patch)

- https://github.com/erlang/otp/commit/3970738f687325138eb75f798054fa8960ac354e (CNA: EEF; patch)

- https://github.com/erlang/otp/commit/696fdec922661d4a3cc528fc34bc24fae8d4ad8a (CNA: EEF; patch)

## Provenance

- CNA: EEF: https://www.cve.org/CVERecord?id=CVE-2026-21620; retrieved 2026-11-11; source updated 2026-11-11

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-21620; retrieved 2026-11-11; source updated Not reported

Revision: 366608e96644b6162e46a1d04ea680ac3a6c4968da6e2fd53d919e550d65c665

Canonical: https://y2.dev/cve/CVE-2026-21620

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