CVE catalog
CVE-2026-59980
hpack is an HTTP/2 Header Encoding for Python. Prior to version 4.2.0, unbounded variable integer decoding can cause run-away computation on malformed input leading to O(n^2) runtime, effectively bloc
- Severity
- Medium · CVSS 6.3
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - Published
- Updated
- Source
- [NVD] · [CVE record]
- EPSS
- 0.30% · Oct 25, 2026
hpack is an HTTP/2 Header Encoding for Python. Prior to version 4.2.0, unbounded variable integer decoding can cause run-away computation on malformed input leading to O(n^2) runtime, effectively blocking further processing with large enough unsanitized input. A fix is available in python-hyper/hpack v4.2.0 to restricted variable integer decoding to uint32 to prevent run-away computation. As a workaround, sanitize input to hpack decoder for long sequences of `0xFF` values to prevent malicious use.
Vulnerable and fixed packages
Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.
| Distribution | Package | Release | Version | Status |
|---|---|---|---|---|
| Debian | python-hpack | sid | 4.0.0-4 | vulnerable |
| Debian | python-hpack | forky | 4.0.0-4 | vulnerable |
| Debian | python-hpack | trixie | 4.0.0-3 | vulnerable |
| Debian | python-hpack | bookworm | 4.0.0-2 | vulnerable |
| PyPI | hpack | Not reported | 4.2.0 | fixed |
| PyPI | hpack | Not reported | 4.2.0 | fixed |
| Suse | python-hpack | linux enterprise module for server applications 15 sp7 | 3.0.0-150200.3.5.1 | fixed |
| Suse | python-hpack | linux enterprise server 16.0 | 4.1.0-160000.3.1 | fixed |
| Suse | python-hpack | linux enterprise server for sap applications 16.0 | 4.1.0-160000.3.1 | fixed |
| Opensuse | python-hpack | leap 16.0 | 4.1.0-160000.3.1 | fixed |
| Suse | python-hpack | linux enterprise module for python 3 15 sp7 | 4.0.0-150400.8.6.1 | fixed |
Fixed-version evidence
| Distribution | Package | Type | Release | Fixed version | Urgency | Origin | Bugs |
|---|---|---|---|---|---|---|---|
| Debian | python-hpack | source | sid | (unfixed) | not yet assigned | Not reported | [1148944] |
| Debian | python-hpack | source | forky | (unfixed) | not yet assigned | Not reported | [1148944] |
| Debian | python-hpack | source | trixie | (unfixed) | not yet assigned | Not reported | [1148944] |
| Debian | python-hpack | source | bookworm | (unfixed) | not yet assigned | Not reported | [1148944] |
| PyPI | hpack | PyPI | Not reported | 4.2.0 | Not reported | GHSA-8V8H-HG4W-MVQ2 | Not reported |
| PyPI | hpack | PyPI | Not reported | 4.2.0 | Not reported | PYSEC-2026-4053 | Not reported |
| Suse | python-hpack | rpm | linux enterprise module for server applications 15 sp7 | 3.0.0-150200.3.5.1 | Not reported | SUSE-SU-2026:4593-1 | Not reported |
| Suse | python-hpack | rpm | linux enterprise server 16.0 | 4.1.0-160000.3.1 | Not reported | SUSE-SU-2026:24216-1 | Not reported |
| Suse | python-hpack | rpm | linux enterprise server for sap applications 16.0 | 4.1.0-160000.3.1 | Not reported | SUSE-SU-2026:24216-1 | Not reported |
| Opensuse | python-hpack | rpm | leap 16.0 | 4.1.0-160000.3.1 | Not reported | OPENSUSE-SU-2026:22070-1 | Not reported |
| Suse | python-hpack | rpm | linux enterprise module for python 3 15 sp7 | 4.0.0-150400.8.6.1 | Not reported | SUSE-SU-2026:4832-1 | Not reported |
Notes
[trixie] python-hpack: Minor issue [bookworm] python-hpack: Minor issue
OpenFactory catalog packages
[Debian 12 (Bookworm)]
- [python3-hpack]Affected
Source package: [python-hpack]
Details (2)
4.0.0-2· all · bookwormAffected
nvd · python-hpack · debian · bookworm; nvd · python-hpack · debian · 12
4.0.0-2· all · bookwormAffected
nvd · python-hpack · debian · bookworm; nvd · python-hpack · debian · 12
[Debian 13 (Trixie)]
- [python3-hpack]Affected
Source package: [python-hpack]
Details (2)
4.0.0-3· all · trixieAffected
nvd · python-hpack · debian · 13
4.0.0-3· all · trixieAffected
nvd · python-hpack · debian · 13
Observed:
References
- [https://ftp.suse.com/pub/projects/security/csaf/opensuse-su-2026_11556-1.json]
- [https://nvd.nist.gov/vuln/detail/CVE-2026-59980]
- [https://osv.dev/vulnerability/DEBIAN-CVE-2026-59980]
- [https://osv.dev/vulnerability/PYSEC-2026-4053]
- [https://osv.dev/vulnerability/SUSE-SU-2026:24216-1]
- [https://osv.dev/vulnerability/SUSE-SU-2026:4593-1]
- [https://osv.dev/vulnerability/SUSE-SU-2026:4832-1]
- [https://osv.dev/vulnerability/openSUSE-SU-2026:22070-1]
- [https://security-tracker.debian.org/tracker/CVE-2026-59980]
- [https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-59980.json]
[Debian Security Tracker] · [FIRST EPSS] · [GitHub Advisory Database] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX] · [SUSE security advisories and VEX]