Security readout for executives and security teams
Plain-English summary
SABnzbd could be tricked by a malicious PAR2 file into placing downloaded files outside the configured Download Folder. The main business risk is unauthorized file creation where the SABnzbd process has write access. Public sources rate this as medium severity, not critical.
Executive priority
Treat this as a moderate-priority hardening and patching item. It is not described as actively exploited, but exposed SABnzbd instances with broad filesystem write permissions have more meaningful operational risk.
Technical view
CVE-2021-29488 is a CWE-23 path traversal issue in SABnzbd's filesystem.renamer() handling of malicious PAR2 files. The CVSS 3.1 score is 4.3: network attack vector, low complexity, low privileges required, no user interaction, and low integrity impact.
Likely exposure
Exposure is limited to SABnzbd deployments running affected versions and processing NZBs with PAR2 files. Impact depends heavily on filesystem permissions granted to the SABnzbd process outside its required working directories.
Exploitation context
The provided sources do not show CISA KEV listing or active exploitation evidence. The advisory describes a malicious PAR2-triggered write outside the Download Folder, but does not provide evidence of public exploitation in the supplied bundle.
Researcher notes
Focus validation on version state, PAR2 processing, and effective filesystem permissions. The affected-version evidence in the bundle lists ranges below 3.0.0 and below 3.2.1; use the GitHub advisory as the controlling vendor source.
Mitigation direction
- Update SABnzbd to a vendor-fixed version, including 3.2.1RC1 or later guidance.
- Restrict SABnzbd process write permissions to only required working directories.
- Limit downloads to NZBs without PAR2 files until fixed.
- Review vendor advisory before applying environment-specific compensating controls.
Validation and detection
- Inventory SABnzbd instances and compare versions against the advisory's affected ranges.
- Confirm SABnzbd process cannot write outside required download and working paths.
- Check whether workflows accept or automatically process PAR2 files.
- Look for unexpected files created outside the configured Download Folder.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-23: File access and web shell behavior lookup
File traversal and upload weaknesses can lead teams to review file, web shell, execution, and collection telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-29488 mapping review
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Open ATT&CK lookup- Severity
- Medium
- CVSS
- 4.3 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N2.81.4Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
4.3MediumVector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/sabnzbd/sabnzbd/security/advisories/GHSA-jwj3-wrvf-v3rpCVE reference · x_refsource_CONFIRM
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Relative Path Traversal
Relative Path Traversal represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.