CVE-2026-15310: zipfile: bzip2/LZMA/Zstandard members decompress without a max_length bound, defeating chunked-read memory limits

Versions reported by the vendor

Affected version ranges reported by the assigning authority (PSF). Independent of NVD's CPE analysis and usually ahead of it.

• Python Software Foundation CPython

  • before 3.12.15affected · python
  • 3.13.0 and later · before 3.13.16affected · python
  • 3.14.0 and later · before 3.14.8affected · python
  • 3.15.0a1 and later · before 3.15.0rc2affected · python

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Other highest-scoring records for the same primary product.

• CVE-2026-115557Distrust compromised intermediate certificates in ssl module
  37Monitor
• CVE-2025-4517Arbitrary writes via tarfile realpath overflow
  37Monitor
• CVE-2026-19445Use-after-free of a server-side SSLContext when sni_callback switches contexts
  36Monitor

Published before and after this one in the same product

• ← EarlierCVE-2026-15806Aug 18, 2026 · `HTTPPasswordMgr` can send saved HTTPS credentials via HTTP because of incorrect scheme matching
  24Monitor
• ← EarlierCVE-2026-19672Aug 19, 2026 · tarfile extraction filter bypass allows creation of directories outside the destination
  25Monitor
• Later →CVE-2026-87910Sep 11, 2026 · tarfile hardlink fallback ignores custom extraction filter rejection via None
  22Monitor

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Root cause

Code that parses nested structures sets no depth or size limit. A small input can turn into a disproportionate processing load.

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

1function expand(node) {2  return node.children.map(expand);3}

1const MAX_DEPTH = 32;2function expand(node, depth = 0) {3  if (depth > MAX_DEPTH) throw new Error("too deep");4  return node.children.map((c) => expand(c, depth + 1));5}

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.