CVE-2026-3644: Incomplete control character validation in http.cookies
Modified
AliasesALPINE-CVE-2026-3644UBUNTU-CVE-2026-3644DEBIAN-CVE-2026-3644CGA-3rjg-h44j-w26vCGA-6q68-qxxc-rv68CGA-7g42-jfcw-ccgwCGA-975c-63xh-w2w9CGA-977h-c34r-5v9jCGA-9vxg-2373-8rm4CGA-cc9q-49v3-r42fCGA-gx3f-vf78-qvcrCGA-jwvc-775q-2843CGA-vr9r-627r-wx6cCGA-fgvw-2hh6-gqj7CGA-xmp7-w2cj-8ggh
Published 16-03-2026Last modified 13-08-2026
Vulnerability summary
CVE-2026-3644 is a high (CVSS 7.5) Improper Input Validation vulnerability in python software foundation cpython. EPSS estimates a 0.51% chance of exploitation in the next 30 days, higher than 43.4% of scored vulnerabilities.
Priority
Routine
Not severe (CVSS 6, network access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?CVSS score
7.5/10
010
High · v3.1 (NVD)EPSS score
0.51%
0%100%
Low · +0.03 pp in 30 daysKEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded
Advisory lineage
Upstream 0 · Downstream 34 · Related 25MGASA-2026-0455OPENSUSE-SU-2026:10469-1OPENSUSE-SU-2026:10477-1OPENSUSE-SU-2026:10478-1OPENSUSE-SU-2026:10479-1OPENSUSE-SU-2026:10480-1OPENSUSE-SU-2026:10481-1OPENSUSE-SU-2026:20517-1RHSA-2026:10950RHSA-2026:19019RHSA-2026:19064RHSA-2026:19176RHSA-2026:19177RHSA-2026:7443RHSA-2026:7661RHSA-2026:8822RHSA-2026:8824SUSE-SU-2026:1206-1SUSE-SU-2026:1292-1SUSE-SU-2026:1296-1SUSE-SU-2026:1345-1SUSE-SU-2026:1349-1SUSE-SU-2026:1354-1SUSE-SU-2026:1376-1SUSE-SU-2026:1385-1SUSE-SU-2026:1417-1SUSE-SU-2026:1530-1SUSE-SU-2026:21104-1SUSE-SU-2026:21178-1SUSE-SU-2026:21254-1SUSE-SU-2026:23743-1SUSE-SU-2026:4534-1USN-8509-1USN-8744-1CGA-X3JX-7XJP-VPM8
Timeline
- 16-03-2026PublishedVulnerability first disclosed.
- 13-08-2026Last modifiedVulnerability information updated.
Description
The fix for CVE-2026-0672, which rejected control characters in http.cookies.Morsel, was incomplete. The Morsel.update(), |= operator, and unpickling paths were not patched, allowing control characters to bypass input validation. Additionally, BaseCookie.js_output() lacked the output validation applied to BaseCookie.output().
CVSS metrics
9 scores · 7 sources · 2 versionsMedium 6.0Preferred score · CVE.org (CNA)
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:NSourcesAll 5 agree
- OSV · UbuntuEcosystem advisory · calculated6.0MediumCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N
- OSV · WolfiEcosystem advisory · calculated6.0MediumCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N
- OSV · ChainguardEcosystem advisory · calculated6.0MediumCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N
- NVDNIST6.0MediumCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:H/VA:N/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
High 7.5Preferred score · NVD (NIST)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:NSourcesAll 4 agree
- OSV · AlpineEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
- OSV · UbuntuEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
- OSV · DebianEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
EPSS trend
Probability
0.51%
Chance of exploitation in the next 30 days
Percentile
43%
Versus all other CVEs
30-day change
Increase +0.03 pp
From 0.48% on 04-10-2026
04-10-202603-11-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-20Improper Input ValidationThe product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
- CWE-116Improper Encoding or Escaping of OutputThe product prepares a structured message for communication with another component, but encoding or escaping of the data is either missing or done incorrectly. As a result, the intended structure of the message is not preserved.
Affected systems
Version check
Known conditions: network-reachable, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.
Ubuntu12 products
- python2.7< 2.7.6-8ubuntu0.6+esm30 | < 2.7.12-1ubuntu0~16.04.18+esm22 | < 2.7.17-1~18.04ubuntu1.13+esm15 | < 2.7.18-13ubuntu1.5+esm9
- python3.10< 3.10.12-1~22.04.16
- python3.11< 3.11.0~rc1-1~22.04.1+esm2
- python3.12< 3.12.3-1ubuntu0.15
- python3.13All versions (No fix recorded)
Chainguard6 products
- python-3.10< 3.10.21-r6
- python-3.11< 3.11.15-r9
- python-3.12< 3.12.14-r8
- python-3.13< 3.13.12-r7
- python-3.14< 3.14.3-r6
Wolfi5 products
- python-3.10< 3.10.21-r6
- python-3.11< 3.11.15-r9
- python-3.12< 3.12.14-r8
- python-3.13< 3.13.12-r7
- python-3.14< 3.14.3-r6
Debian3 products
- python3.11< 3.11.2-6+deb12u8
- python3.13< 3.13.14-1 | < 3.13.5-2+deb13u2
- python3.14< 3.14.3-4
Alpine1 product
- python3< 3.12.14-r0 | < 3.14.5-r0
Python1 product
- python< 3.13.13 | ≥ 3.14.0, < 3.14.4 | 3.15.0:alpha1 | 3.15.0:alpha2 | 3.15.0:alpha3 | 3.15.0:alpha4 | 3.15.0:alpha5 | 3.15.0:alpha6 | 3.15.0:alpha7
Python software foundation1 product
- cpython< 3.10.21 | ≥ 3.11.0, < 3.11.16 | ≥ 3.12.0, < 3.12.14 | ≥ 3.13.0, < 3.13.13 | ≥ 3.14.0, < 3.14.4 | ≥ 3.15.0a1, < 3.15.0a8
7 vendors · 29 products
References
18 links- mail.python.org/archives/list/security-announce@python.org/thread/H6CADMBCDRFGWCMOXWUIHFJNV43GABJ7/Vendor AdvisoryREPORTAdvisoryThird Party Advisory
Show all 18 references
- github.com/python/cpythonPACKAGE