Vulnerability in pyzipper (CVE-2026-44722)
Summary
Vulnerability in pyzipper (CVE-2026-44722). Confidential information can be exposed externally. Mitigation: upgrade to 0.4.0 or later.
Original description
The description as published by the source.
Impact
A Python operator precedence bug in pyzipper/zipfile_aes.py caused the AE-2 format to never be automatically selected during encryption, regardless of file size or compression type. As a result, all encrypted entries are written in AE-1 format unless AE-2 is explicitly forced by the caller. AE-1 stores the plaintext CRC32 checksum unencrypted in the ZIP header. During investigation of this issue, it was also found that when writing to an unseekable zip archive, the CRC32 value was always written to the datadescripter section.
The AES encryption itself is not broken. An attacker who possesses the archive can read the CRC32 from the header without decrypting anything, then brute-force candidate plaintexts by computing CRC32(candidate) and comparing against the stored value. In practice, this attack is feasible today only against small or low-entropy files, as CRC32 exhaustion across a large plaintext space is computationally prohibitive on current hardware. Files with high-entropy or large content are not practically at risk under current computing constraints. Without this bug, pyzipper would have removed the CRC32 value for any file with content of less than 20 bytes uncompressed.
Patches
Upgrade to pyzipper 0.4.0 that changes the default behaviour of pyzipper to always use the AE-2 format and exclude the CRC32 values, unless instructed to do otherwise.
If rewriting the zip archive to remove the CRC values for small files, the entire zip archive should be re…
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-44722 has been found in pyzipper.
Confidential information can be exposed externally. CVSS score: 6.2/10.
What to do: upgrade pyzipper to 0.4.0 or later.
If unsure, ask your IT team or search "pyzipper CVE-2026-44722" on the vendor's site.
CVE-2026-44722 (pyzipper) — CWE-480 / CVSS v3 6.2
Attack vector: local / unauthenticated / no user interaction
Patched: 0.4.0 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-480) exists in pyzipper.
Check the vendor advisory for the affected versions of pyzipper.
Severity: Medium (CVSS 6.2/10). Confidential information can be exposed externally.
Update to 0.4.0.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'pyzipper' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'pyzipper' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
pyzipperを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade pyzipper to 0.4.0ステージング環境で 0.4.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Ubuntu UBUNTU-CVE-2026-44722 python-pyzipper
References
- package github.com
- web github.com
- web github.com
- web github.com
- web security-advisories@github.com