CVE-2026-0865 | wsgiref.headers.Headers allows header newline injection

User-controlled header names and values containing newlines can allow injecting HTTP headers.

Published: 2026-01-20 Last update: 2026-04-15 Assigner: [email protected] Source: [email protected]
NVD Status：Deferred，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-0865 is rated Low Risk (36.9/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.17%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-0865

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-22 0.13% 0.17% +0.04%
2 2026-03-16 0.15% 0.13% -0.03%
3 2026-02-18 — 0.15% —

Full EPSS history (4 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-0865

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.9 4.0 MEDIUM
CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:N/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 Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network.
Attack complexity (AC:L)
Exploitation conditions are straightforward and stable.
Attack requirements (AT:P)
Additional preconditions must be present for exploitation.
Privileges required (PR:H)
High privileges are required.
User interaction (UI:N)
No user interaction is required.
Vulnerable system confidentiality impact (VC:N)
No confidentiality impact on the vulnerable system.
Vulnerable system integrity impact (VI:H)
High integrity impact on the vulnerable system.
Vulnerable system availability impact (VA:N)
No availability impact on the vulnerable system.
Subsequent system confidentiality impact (SC:N)
No confidentiality impact on subsequent systems.
Subsequent system integrity impact (SI:N)
No integrity impact on subsequent systems.
Subsequent system availability impact (SA:N)
No availability impact on subsequent systems.
Exploit maturity (threat) (E:X)
Not defined: no reliable threat intelligence; scoring assumes the worst case (equivalent to Attacked).
Confidentiality requirement (CR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Integrity requirement (IR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Availability requirement (AR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Modified attack vector (MAV:X)
Not defined: scoring uses the Base Attack Vector (AV).
Modified attack complexity (MAC:X)
Not defined: scoring uses the Base Attack Complexity (AC).
Modified attack requirements (MAT:X)
Not defined: scoring uses the Base Attack Requirements (AT).
Modified privileges required (MPR:X)
Not defined: scoring uses the Base Privileges Required (PR).
Modified user interaction (MUI:X)
Not defined: scoring uses the Base User Interaction (UI).
Modified vulnerable system confidentiality impact (MVC:X)
Not defined: scoring uses the Base VC metric.
Modified vulnerable system integrity impact (MVI:X)
Not defined: scoring uses the Base VI metric.
Modified vulnerable system availability impact (MVA:X)
Not defined: scoring uses the Base VA metric.
Modified subsequent system confidentiality impact (MSC:X)
Not defined: scoring uses the Base SC metric.
Modified subsequent system integrity impact (MSI:X)
Not defined: scoring uses the Base SI metric.
Modified subsequent system availability impact (MSA:X)
Not defined: scoring uses the Base SA metric.
Safety (supplemental) (S:X)
Not evaluated.
Automatable (supplemental) (AU:X)
Not evaluated.
Recovery (supplemental) (R:X)
Not evaluated.
Value density (supplemental) (V:X)
Not evaluated.
Vulnerability response effort (supplemental) (RE:X)
Not evaluated.
Provider urgency (supplemental) (U:X)
Not evaluated.
 — — [email protected]

Weakness enumeration for CVE-2026-0865

OS Trackers for CVE-2026-0865

vendor priority summary link
debian end-of-life CVE-2026-0865 end-of-life priority: Debian including 7 source packages (jython, pypy3, …), 18 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): open 9, resolved 9. https://security-tracker.debian.org/tracker/CVE-2026-0865
redhat medium — https://access.redhat.com/security/cve/CVE-2026-0865
suse medium — https://www.suse.com/security/cve/CVE-2026-0865/
ubuntu medium CVE-2026-0865 medium priority: Ubuntu including 12 source packages (python2.7, python3.10, …), 60 status rows across 8 suites (bionic, focal, jammy, noble, questing, trusty, upstream, xenial): DNE 30, released 18, needs-triage 12. https://ubuntu.com/security/CVE-2026-0865

Affected software / configurations for CVE-2026-0865

Vendor Product Version Raw CPE
No affected products in dataset.

References for CVE-2026-0865

URL Tags
https://github.com/python/cpython/commit/22e4d55285cee52bc4dbe061324e5f30bd4dee58
https://github.com/python/cpython/commit/23e3c0ae867cca0130e441e776c9955b9027c510
https://github.com/python/cpython/commit/286e3ac39984fe85a17f4ab39c64d382137aae5f
https://github.com/python/cpython/commit/2f840249550e082dc351743f474ba56da10478d2
https://github.com/python/cpython/commit/4802b96a2cde58570c24c13ef3289490980961c5
https://github.com/python/cpython/commit/66da7bf6fe7b81e3ecc9c0a25bd47d4616c8d1a6
https://github.com/python/cpython/commit/83ecd18779f286d872f68bfce175651e407d9fff
https://github.com/python/cpython/commit/8bb044d29310bb05d15086cdaa8bf64867d61a97
https://github.com/python/cpython/commit/bfba660085767f8c2d582134e9d511a85eda04cf
https://github.com/python/cpython/commit/c592227ffb48679af9845a45dbb0875d975bb219
https://github.com/python/cpython/commit/e4846a93ac07a8ae9aa18203af0dd13d6e7a6995
https://github.com/python/cpython/commit/f7fceed79ca1bceae8dbe5ba5bc8928564da7211
https://github.com/python/cpython/issues/143916
https://github.com/python/cpython/pull/143917
https://mail.python.org/archives/list/[email protected]/thread/BJ6QPHNSHJTS3A7CFV6IBMCAP2DWRVNT/
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