What is the CVSS score of CVE-2026-45070?

CVE-2026-45070 has a CVSS 4.0 base score of 6.3 (Medium). CVSS vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. EPSS exploitation probability: 0.1%.

Is there a public PoC exploit available for CVE-2026-45070?

Yes, a public proof-of-concept exploit is available for CVE-2026-45070. Prioritise patching immediately. EPSS: 0.1%.

Is there a patch available for CVE-2026-45070?

Yes, a patch is available for CVE-2026-45070. Update the affected software to the latest version immediately.

CVE-2026-45070

EUVD-2026-44346 MEDIUM

Improper Neutralization of CRLF Sequences ('CRLF Injection') (CWE-93)

2026-05-27 https://github.com/symfony/symfony

GHSA-vqc8-7275-q272

Code Injection

6.3

CVSS 4.0 · Vendor: https://github.com/symfony/symfony

View

Vulnerability Assessment

Weakness

CWE

CWE-93

OWASP Top 10:2025

A05:2025 - Injection

ASVS 5.0

V1 - Encoding and Sanitization CRLF sequence sanitization

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).

Patch available 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – May 27, 2026

Header injection in Symfony's Mime component (symfony/mime) enables attackers to inject arbitrary MIME headers into serialized email messages when an application passes untrusted input as a parameter name to ParameterizedHeader. The component correctly encodes parameter values per RFC 2045/5322 but emits parameter names verbatim, meaning CRLF sequences in a user-influenced parameter name terminate the current header line and allow arbitrary new headers to be appended. No active exploitation is confirmed (not in CISA KEV), no public exploit code has been identified, and vendor-released patches are available across all supported Symfony branches.

Affected VersionsENISA

mime 7.0.0-BETA1, < 7.4.12

symfony 7.0.0-BETA1, < 7.4.12

symfony < 5.4.52

mime 8.0.0-BETA1, < 8.0.12

mime < 5.4.52

mime 6.0.0-BETA1, < 6.4.40

symfony 6.0.0-BETA1, < 6.4.40

symfony 8.0.0-BETA1, < 8.0.12

Affected Packages

composer symfony/mime fix: 5.4.52, 6.4.40, 7.4.12, 8.0.12

composer symfony/symfony fix: 5.4.52, 6.4.40, 7.4.12, 8.0.12

euvd mime fix: 5.4.52

euvd mime_6_0_0_beta1 fix: 6.4.40

euvd mime_7_0_0_beta1 fix: 7.4.12

euvd mime_8_0_0_beta1 fix: 8.0.12

euvd symfony fix: 5.4.52

euvd symfony_6_0_0_beta1 fix: 6.4.40

euvd symfony_7_0_0_beta1 fix: 7.4.12

euvd symfony_8_0_0_beta1 fix: 8.0.12

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 10 packages in composer, euvd

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (https://github.com/symfony/symfony) PRIMARY 6.3 MEDIUM

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (https://github.com/symfony/symfony) · only source for this CVE.

CVSS VectorVendor: https://github.com/symfony/symfony

Attack Vector

Network

Attack Complexity

Low

Attack Requirements

Present

Privileges Required

None

User Interaction

None

Vulnerable system: Confidentiality

None

Vulnerable system: Integrity

Low

Vulnerable system: Availability

None

Subsequent system: Confidentiality

None

Subsequent system: Integrity

None

Subsequent system: Availability

None

Lifecycle Timeline

CVSS changed

Jul 14, 2026 - 19:22 NVD

6.3 (MEDIUM)

DescriptionCVE.org

Description

Symfony\Component\Mime\Header\ParameterizedHeader (and the related parameter handling reachable from Symfony\Component\Mime\Header\Headers) is responsible for serializing structured headers such as Content-Type and Content-Disposition, which carry key=value parameters (e.g. Content-Disposition: attachment; filename="x").

RFC 2045 / RFC 5322 require parameter *names* to be tokens: a restricted ASCII subset that excludes whitespace, CR/LF, and the tspecials set. Symfony's parameter handling validates and properly encodes parameter *values*, but does not validate parameter *names*: the supplied name is emitted verbatim into the serialized header.

A caller that derives a parameter name from untrusted input, e.g. an application that lets a user influence a Content-Disposition parameter name, can include \r\n or other non-token bytes inside the name, terminating the current header and injecting additional headers in the rendered message. This is the classic CRLF / header-injection primitive applied to the parameter-name slot.

Resolution

ParameterizedHeader now rejects parameter names that contain bytes outside the RFC token character class.

The patch for this issue is available here for branch 5.4.

Credits

Symfony would like to thank Fabian Fleischer for reporting the issue and Alexandre Daubois for fixing it.

Threat Intelligence Overview

EPSS Score

0.1%

Top 82% exploitable

Threat Intel

1 source

Exploit

POC

Public exploit code exists

Social Media

Sightings

Data Quality

5 sources

Confidence: Medium

EUVD

NVD

CVE.org

EPSS GHSA CIRCL

GitHub

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity MEDIUM

CISA KEV No

Public POC Yes

EPSS 0.1%

Patch available Yes

Active threat No

Deciding rule

MEDIUM severity (CVSS 4.0-6.9)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Scheduled

Exploitation· derived

Poc

System Exposure· derived

Open

Automatable· derived

Yes

Human Impact· derived

Medium

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +32

PoC: +20

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Code Injection CRITICAL

Code injection occurs when an application accepts user input and passes it directly into a language interpreter or evaluator without proper sanitization.