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Public proof of conceptFix available

CVE-2021-43811

A public proof of concept exists; no exploitation attested.

  • Published2021-12-08
  • Fixed in2.3.24
  • WeaknessCWE-94

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

Sockeye is an open-source sequence-to-sequence framework for Neural Machine Translation built on PyTorch. Sockeye uses YAML to store model and data configurations on disk. Versions below 2.3.24 use unsafe YAML loading, which can be made to execute arbitrary code embedded in config files. An attacker can add malicious code to the config file of a trained model and attempt to convince users to download and run it. If users run the model, the embedded code will run locally. The issue is fixed in version 2.3.24.

Timeline

dates in UTC
  1. 2021-12-0823:15CVE publishedNVD
  2. 2026-10-2319:23First public proof of conceptPoC-in-GitHub

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-43811?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-43811?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD · OSV
Amazon sockeye
BranchAffectedFixed in
2.3< 2.3.242.3.24

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

  1. Update Amazon sockeye to 2.3.24

Advisories and patches

Detection

read 2026-10-23 19:23 UTC
Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
1 repository, unverifieds-index/CVE-2021-43811
PoC-in-GitHub

Sources

  • CNACVSS 3.17.8read 2026-10-23
  • NVDCVSS 2.06.8read 2026-10-23
  • CNAweakness (CWE)CWE-94read 2026-10-23
  • FIRST EPSSEPSS score2.5 %2026-10-23
  • PoC-in-GitHubproof of concept1read 2026-10-23
  • OSVaffected packages—

Technical details

CVSS v3 Vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Published
2021-12-08
Last Modified
2026-06-17
NVD status
Modified

Frequently asked questions

What is CVE-2021-43811?

Sockeye is an open-source sequence-to-sequence framework for Neural Machine Translation built on PyTorch. Sockeye uses YAML to store model and data configurations on disk. Versions below 2.3.24 use unsafe YAML loading, which can be made to execute arbitrary code embedded in config files. An attacker can add malicious code to the config file of a trained model and attempt to convince users to download and run it. If users run the model, the embedded code will run locally. The issue is fixed in version 2.3.24.

Is CVE-2021-43811 actively exploited?

Active exploitation of CVE-2021-43811 has not been confirmed. Its EPSS score was 2.5% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-43811?

CVE-2021-43811 has a CVSS v3 base score of 7.8 (HIGH severity), with vector string CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

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