How severe is GHSA-xx3c-qf5g-hc39?

No CVSS score has been assigned to GHSA-xx3c-qf5g-hc39 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-xx3c-qf5g-hc39?

GHSA-xx3c-qf5g-hc39 affects the following packages: symfony/mailer (Packagist), symfony/symfony (Packagist), symfony/mailer (Packagist), symfony/mailer (Packagist), symfony/mailer (Packagist), symfony/symfony (Packagist), symfony/symfony (Packagist), symfony/symfony (Packagist). Ecosystems affected: Packagist.

How do I fix GHSA-xx3c-qf5g-hc39?

Update symfony/mailer to 5.4.52 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-xx3c-qf5g-hc39 is resolved across your whole dependency graph.

How do I detect GHSA-xx3c-qf5g-hc39 in my Packagist dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for symfony/mailer, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate GHSA-xx3c-qf5g-hc39 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is GHSA-xx3c-qf5g-hc39 actively exploited in the wild?

No public exploit code has been indexed for GHSA-xx3c-qf5g-hc39 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-xx3c-qf5g-hc39?

GHSA-xx3c-qf5g-hc39 has an EPSS (Exploit Prediction Scoring System) score of 0.5%, placing it in the 43th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-xx3c-qf5g-hc39?

GHSA-xx3c-qf5g-hc39 is classified as CWE-88 (CWE-88). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-xx3c-qf5g-hc39 published, and has it been updated?

GHSA-xx3c-qf5g-hc39 was published on May 27, 2026 and was last updated on September 10, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐘 Packagist

Not in CISA KEV

Symfony has an Argument Injection in SendmailTransport via Dash-Prefixed Recipient AddressGHSA-xx3c-qf5g-hc39

Fix: symfony/symfony@c451448

GHSA-xx3c-qf5g-hc39 is a CWE-88 vulnerability in symfony/mailer. A fix is available for symfony/mailer — see the affected versions and patch details below.

Also known asCVE-2026-45068

Published

May 27, 2026

Updated

Sep 10, 2026

Affected

8 pkgs

Patched

8 / 8

Exploits

None indexed

Exploitation data as of Oct 9, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-xx3c-qf5g-hc39.

EPSS Exploitation Probability

via FIRST.org ↗

0.5%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs43th percentile — riskier than 43% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

8 pkgs affected

🐘symfony/mailer🐘symfony/symfony🐘symfony/mailer🐘symfony/mailer🐘symfony/mailer🐘symfony/symfony🐘symfony/symfony🐘symfony/symfony

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.

Description

Symfony Mailer selects a transport via the MAILER_DSN environment variable / configuration (e.g. smtp://..., sendmail://..., native://default). SendmailTransport invokes the local sendmail binary and supports two modes: -bs (speak SMTP over stdin: the default) and -t (read the message on stdin, pass recipients as command-line arguments).

In -t mode, recipient addresses are appended to the sendmail command line without a -- end-of-options separator. A recipient address beginning with - (which Symfony\Component\Mime\Address accepts as valid) is therefore interpreted by sendmail as a command-line option rather than an address.

Resolution

The SendmailTransport transport now ensure -- is set before the list of recipients.

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

Credits

Symfony would like to thank Claude Mythos Preview (via Project Glasswing) for reporting the issue and providing the fix.

Affected Packages

8 total 8 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`symfony/mailer`	all versions	5.4.52`composer require symfony/mailer:^5.4.52`
🐘Packagist	`symfony/symfony`	all versions	5.4.52`composer require symfony/symfony:^5.4.52`
🐘Packagist	`symfony/mailer`	≥ 6.0.0&&< 6.4.40	6.4.40`composer require symfony/mailer:^6.4.40`
🐘Packagist	`symfony/mailer`	≥ 7.0.0&&< 7.4.12	7.4.12`composer require symfony/mailer:^7.4.12`
🐘Packagist	`symfony/mailer`	≥ 8.0.0&&< 8.0.12	8.0.12`composer require symfony/mailer:^8.0.12`
🐘Packagist	`symfony/symfony`	≥ 6.0.0&&< 6.4.40	6.4.40`composer require symfony/symfony:^6.4.40`

Affected Products

1 product · 4 configurations

Application

symfonysensiolabs

≥ 8.0.0 && < 8.0.12

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for symfony/mailer, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update symfony/mailer to 5.4.52 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-xx3c-qf5g-hc39 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

### Description Symfony Mailer selects a transport via the `MAILER_DSN` environment variable / configuration (e.g. `smtp://...`, `sendmail://...`, `native://default`). `SendmailTransport` invokes the local `sendmail` binary and supports two modes: `-bs` (speak SMTP over stdin: the default) and `-t` (read the message on stdin, pass recipients as command-line arguments). In `-t` mode, recipient addresses are appended to the sendmail command line **without a `--` end-of-options separator**. A recipient address beginning with `-` (which `Symfony\Component\Mime\Address` accepts as valid) is there

O3 Security · Impact-Aware SCA

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Symfony has an Argument Injection in SendmailTransport via Dash-Prefixed Recipient AddressGHSA-xx3c-qf5g-hc39

Exploitation Status

No confirmed exploitation observed yet

EPSS Exploitation Probability

Real-World Exposure

Description

Description

Resolution

Credits

Affected Packages

Affected Products

Detection & mitigation playbook

Detect

Fix

Workarounds

Frequently Asked Questions

Is GHSA-xx3c-qf5g-hc39 in your dependencies?