CVE-2026-47731: NASA AMMOS Instrument Toolkit: Path traversal resulting in arbitrary file append (can be triggered over the network by unauthenticated attacker)

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• Not in CISA KEV, but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
• EPSS 0.9%, percentile 58: FIRST’s model estimates a 0.9% chance of exploitation activity in the next 30 days, higher than 58% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Only applies if your dependency tree includes ait-core (PyPI) = 3.1.0, fixed in 3.1.1; ait-core (PyPI) < 2.6.1, fixed in 2.6.1. Check your lockfile, including transitive dependencies.

What it is

The AMMOS Instrument Toolkit (Formerly the Bespoke Links to Instruments for Surface and Space (BLISS)) is a Python-based software suite developed to handle Ground Data System (GDS), Electronic Ground Support Equipment (EGSE), commanding, telemetry uplink/downlink, and sequencing for instrument and CubeSat Missions. In versions prior to 2.6.1 and in version 3.1.0, the Binary Stream Capture (BSC) component exposes an unauthenticated HTTP API for dynamically creating packet capture "handlers." Because the code blindly trusts path‑related form fields, a remote client can bypass the configured log root and direct BSC to log to arbitrary filesystem paths (path traversal / directory escape), and append attacker‑controlled data to those files, using the privileges of theait-bsc process. There are two ways for a remote attacker to trigger this. First, if the attacker has access to the network where ait-bsc is deployed (a reason for that could be that the ports are publicly accessible), the payloads can be directly sent to the server to trigger the arbitrary file append. This type of attack is demonstrated in pythonpoc.py. Second, even if the attacker does not have direct access to the network because the software is running in a local network, it is possible to exploit this if a bad actor in that network opens an attacker-controlled website (which might be a website created by an attacker, or a third-party website compromised by the attacker). The browser javascript can automatically send the requests necessary to exploit this into the local network. This is even possible if the server is only accessible on localhost. This type of attack is demonstrated by attackertcp.py and test1.html (first launch the attacker TCP server, then start a webserver to host test1.html, for example using python3 -m http.server 7000, and open test1.html).This issue affects BSC (Binary Stream Capture) and usage of the ait-bsc server. This impacts AIT-Core versions before 3.1.1, from 2.x before 2.6.1. Users are recommended to upgrade to version 3.1.1 or 2.6.1.

From the GitHub advisory

1. Summary

The Binary Stream Capture (BSC) component exposes an unauthenticated HTTP API for dynamically creating packet capture “handlers.” Because the code blindly trusts path‑related form fields, a remote client can:

- Bypass the configured log root and direct BSC to log to arbitrary filesystem paths (path traversal / directory escape), and - Append attacker‑controlled data to those files, using the privileges of theait-bsc process.

There are two ways for a remote attacker to trigger this: 1. If the attacker has access to the network where ait-bsc is deployed (a reason for that could be that the ports are publicly accessible), the payloads can be directly sent to the server to trigger the arbitrary file append. This type of attack is demonstrated in pythonpoc.py. 2. Even if the attacker does not have direct access to the network because the software is running in a local network, it is possible to exploit this if a bad actor in that network opens an attacker-controlled website (which might be a website created by an attacker, or a third-party website compromised by the attacker). The browser javascript can automatically send the requests necessary to exploit this into the local network. This is even possible if the server is only accessible on localhost. This type of attack is demonstrated by attackertcp.py and test1.html (first launch the attacker TCP server, then start a webserver to host test1.html, for example using python3 -m http.server 7000, and open test1.html).

Impact

Weakness type: CWE-22.

Product: ait-core (PyPI) · Assigned by: GitHub_M · Published: 2026-07-21

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: none (no login)
• User interaction: none
• Scope: unchanged

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation poc, automatable yes, technical impact partial.
• FIRST EPSS (model of 2026-10-21): 0.86% probability of exploitation activity in the next 30 days; percentile 58.

Timeline

• 2026-06-05 — GitHub-reviewed advisory GHSA-p462-prxw-mjx4 published (critical)
• 2026-07-21 — CVE record published by GitHub_M
• 2026-07-22 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-p462-prxw-mjx4 github.com
2. CVE.org record CVE-2026-47731 cve.org
3. NVD entry CVE-2026-47731 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. github.com github.com

Critical PyPI advisories · Today’s Security Digest