PYSEC-2026-2973 py7zr: O(n^2) algorithmic complexity DoS in PackInfo._read()

Summary PackInfo.read uses an On^2 cumulative sum pattern where numstreams is read directly from the archive header. A crafted .7z archive with a large numstreams value causes excessive CPU consumption during SevenZipFile.init — no extraction is needed. A 50 KB archive takes 7 seconds of CPU time...

PT-2026-59604

Summary PackInfo. read uses an On^2 cumulative sum pattern where numstreams is read directly from the archive header. A crafted .7z archive with a large numstreams value causes excessive CPU consumption during SevenZipFile. init — no extraction is needed. A 50 KB archive takes 7 seconds of CPU...

CVE-2026-55206: Inefficient Algorithmic Complexity

py7zr is a Python-based library and utility to support 7zip archive compression, decompression, encryption and decryption. Prior to 1.1.3, PackInfo.read in archiveinfo.py used an On^2 cumulative sum pattern for attacker-controlled numstreams values parsed from archive headers, allowing a crafted...

sp1 has insufficient observation of cumulative sum

During proof generation, the prover must observe all values sent to the verifier to generate valid Fiat-Shamir challenges. Prior to v3.0.0 the cumulative sum of the permutation argument was not observed when sampling zeta, which is a random challenge sampled to force the constraints to be true. I...

PT-2024-40198 · Sp1 · Sp1

Name of the Vulnerable Software and Affected Versions: SP1 versions prior to 3.0.0 Description: The issue arises during proof generation, where the prover must observe all values sent to the verifier to generate valid Fiat-Shamir challenges. In versions prior to 3.0.0, the cumulative sum of the...

Moving average precision is lost

Lines of code Vulnerability details Now the precision is lost in moving average calculations as the difference is calculated separately and added each time, while it typically can be small enough to lose precision in the division involved. For example, 10000 moves of 990 size, numObservations =...