PatchSiren

PatchSiren cyber security CVE debrief

CVE-2026-116844 fclairamb CVE debrief

Fclairamb ftpserverlib through 0.32.4 contains a cleartext transmission vulnerability. The CVE record was published on 2026-10-27T00:34:02.373Z and has not been modified since then. The vulnerability allows on-path attackers to read or modify file contents and directory listings when a client sends PROT P after PASV or PORT, despite mandatory encryption. Defenders should assess exposure and verify FTPES data transfer encryption. This AI-assisted debrief is based on the supplied source corpus.

Vendor
fclairamb
Product
ftpserverlib
CVSS
MEDIUM 6.3
CISA KEV
Not listed in stored evidence
Original CVE published
2026-10-27
Original CVE updated
2026-10-29
Advisory published
2026-10-27
Advisory updated
2026-10-29

Who should care

Defenders responsible for ftpserverlib and Syncplify Server! deployments should assess exposure and verify FTPES data transfer encryption. They should prioritize verifying FTPES data transfer encryption and validating PROT command handling in ftpserverlib versions up to 0.32.4 to prevent on-path attacks. This includes reviewing compensating controls for exposed systems and tracking exceptions.

Why it matters

Defenders should prioritize verifying FTPES data transfer encryption and validating PROT command handling in ftpserverlib versions up to 0.32.4 to prevent on-path attacks.

  • On-path attackers can read file contents and directory listings
  • On-path attackers can modify file contents and directory listings
  • Verification of PROT command handling is required
  • Validation of FTPES data transfer encryption is necessary

Technical summary

Fclairamb ftpserverlib through 0.32.4 contains a cleartext transmission vulnerability because TransferOpen checks only the transferTLS flag set by PROT, not whether the prepared data connection uses TLS. This allows on-path attackers to read or modify file contents and directory listings when a client sends PROT P after PASV or PORT, despite mandatory encryption. The vulnerability has been confirmed in ftpserverlib versions up to 0.32.4 and affects Syncplify Server! versions up to 8.8.0. Defenders should prioritize verifying FTPES data transfer encryption and validating PROT command handling.

Defensive priority

Defenders should prioritize verifying FTPES data transfer encryption and validating PROT command handling in ftpserverlib versions up to 0.32.4.

Recommended defensive actions

  • Verify FTPES data transfer encryption in ftpserverlib versions up to 0.32.4
  • Validate PROT command handling in ftpserverlib
  • Assess exposure of ftpserverlib in Syncplify Server! versions up to 8.8.0
  • Review compensating controls for exposed systems while remediation is scheduled and verified
  • Check relevant monitoring, detection, and logs for exposed assets that need extra review
  • Track exceptions, retest remediated assets, and close the item only after evidence is documented
  • Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and source item provide details on the cleartext transmission vulnerability in Fclairamb ftpserverlib through 0.32.4. Evidence is based on official CVE Program and cvelistV5 sources. The vulnerability has been confirmed in ftpserverlib versions up to 0.32.4. Defenders should verify FTPES data transfer encryption and validate PROT command handling.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-116844 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-116844

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-116844 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-116844

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • Fclairamb ftpserverlib through 0.32.4 Cleartext FTPES Data Transfer via PROT P

    Unverified legacy reference

    URL: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/116xxx/CVE-2026-116844.json

    cve_program_cvelist_v5

  • Source reference

    Unverified legacy reference

    URL: https://github.com/fclairamb/ftpserverlib/pull/685

    Supplemental source - patch, issue-tracking

  • Source reference

    Unverified legacy reference

    URL: https://github.com/fclairamb/ftpserverlib/blob/v0.32.4/handle_misc.go

    Supplemental source - technical-description

  • Source reference

    Unverified legacy reference

    URL: https://github.com/fclairamb/ftpserverlib/blob/v0.32.4/client_handler.go

    Supplemental source - technical-description

  • Source reference

    Unverified legacy reference

    URL: https://www.vulncheck.com/advisories/fclairamb-ftpserverlib-through-0.32.4-cleartext-ftpes-data-transfer-via-prot-p

    Supplemental source - third-party-advisory

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.