How severe is CVE-2026-48784?

No CVSS score has been assigned to CVE-2026-48784 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-48784?

CVE-2026-48784 affects the following packages: symfony/routing (Packagist), symfony/routing (Packagist), symfony/routing (Packagist), symfony/routing (Packagist), symfony/symfony (Packagist), symfony/symfony (Packagist), symfony/symfony (Packagist), symfony/symfony (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2026-48784?

Update symfony/routing to 5.4.53 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-48784 is resolved across your whole dependency graph.

How do I detect CVE-2026-48784 in my Packagist dependencies?

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

How do I mitigate CVE-2026-48784 if there is no patch (or I can't update yet)?

Stop reflecting attacker-controlled destinations: resolve every redirect target against an allowlist of paths or hosts you own, prefer a server-side key over a full URL in the request, and reject absolute URLs entirely where the flow only ever needs a relative one.

Is CVE-2026-48784 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-48784 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 CVE-2026-48784?

CVE-2026-48784 has an EPSS (Exploit Prediction Scoring System) score of 0.3%, placing it in the 26th 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 CVE-2026-48784?

CVE-2026-48784 is classified as CWE-172 (CWE-172), Open Redirect (CWE-601). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-48784 published, and has it been updated?

CVE-2026-48784 was published on July 14, 2026 and was last updated on August 12, 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

CVE-2026-48784 — routing

Fix: symfony/symfony@4b63c3a

CVE-2026-48784 is a CWE-172 vulnerability in symfony/routing. A fix is available for symfony/routing — see the affected versions and patch details below.

Symfony: UrlGenerator Dot-Segment Encoding Skips Every Other Chained `../` or `./` → Generated URL Collapses Off-Route Under RFC 3986 Normalization

Also known asGHSA-h5x3-xfc9-m39h

Published

Jul 14, 2026

Updated

Aug 12, 2026

Affected

8 pkgs

Patched

8 / 8

Exploits

None indexed

Exploitation data as of Oct 6, 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 CVE-2026-48784.

EPSS Exploitation Probability

via FIRST.org ↗

0.3%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs26th percentile — riskier than 26% of all scored CVEsHighest risk

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

Real-World Exposure

8 pkgs affected

🐘symfony/routing🐘symfony/routing🐘symfony/routing🐘symfony/routing🐘symfony/symfony🐘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\Component\Routing\Generator\UrlGenerator::doGenerate() percent-encodes . and .. path segments so that the generated URL still resolves to the originating route after RFC 3986 §5.2.4 dot-segment removal (which strict RFC-3986 consumers — routers, reverse proxies, HTTP clients — perform before percent-decoding).

The encoding was implemented as strtr($url, ['/../' => '/%2E%2E/', '/./' => '/%2E/']) plus a trailing-segment fixup. strtr advances past the trailing / of each match, so the next dot-segment in a chained sequence was left unescaped:

Input	Output (before fix)	Expected
`/../../../`	`/%2E%2E/../%2E%2E/`	`/%2E%2E/%2E%2E/%2E%2E/`
`/foo/../../../bar`	`/foo/%2E%2E/../%2E%2E/bar`	`/foo/%2E%2E/%2E%2E/%2E%2E/bar`

When a route exposes a parameter constrained by a permissive requirement (.+, .*, or similar) that accepts dots and slashes, attacker-controlled chained .. or . segments produce a generated URL that, under strict RFC 3986 normalization, collapses to a different path than the originating route. The Twig path() / url() helpers and any server-side use of UrlGenerator are affected. Same class of route round-trip integrity issue as CVE-2026-45065.

Note: WHATWG-conformant browsers treat %2E/%2E%2E as dot-segments during URL parsing, so the encoding never protected browser-side traversal. The defense exists for RFC-3986-conformant consumers; restoring it for chained segments closes the gap there.

Resolution

UrlGenerator now matches every /. or /.. dot-segment in a single left-to-right preg_replace_callback pass using a lookahead that does not consume the trailing /, so adjacent dot-segments are encoded correctly.

The patches for this issue are available here for branch 5.4 (and forward-ported to 6.4, 7.4, 8.0 and 8.1).

Credits

Symfony would like to thank Alex Pott for reporting the issue and Nicolas Grekas for providing the fix.

Affected Packages

8 total 8 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`symfony/routing`	all versions	5.4.53`composer require symfony/routing:^5.4.53`
🐘Packagist	`symfony/routing`	≥ 6.0.0&&< 6.4.41	6.4.41`composer require symfony/routing:^6.4.41`
🐘Packagist	`symfony/routing`	≥ 7.0.0&&< 7.4.13	7.4.13`composer require symfony/routing:^7.4.13`
🐘Packagist	`symfony/routing`	≥ 8.0.0&&< 8.0.13	8.0.13`composer require symfony/routing:^8.0.13`
🐘Packagist	`symfony/symfony`	all versions	5.4.53`composer require symfony/symfony:^5.4.53`
🐘Packagist	`symfony/symfony`	≥ 6.0.0&&< 6.4.41	6.4.41`composer require symfony/symfony:^6.4.41`

Affected Products

1 product · 4 configurations

Application

symfonysensiolabs

≥ 8.0.0 && < 8.0.13

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/routing, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update symfony/routing to 5.4.53 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-48784 is resolved across your whole dependency graph.
Workarounds
Stop reflecting attacker-controlled destinations: resolve every redirect target against an allowlist of paths or hosts you own, prefer a server-side key over a full URL in the request, and reject absolute URLs entirely where the flow only ever needs a relative one.

Frequently Asked Questions

### Description `Symfony\Component\Routing\Generator\UrlGenerator::doGenerate()` percent-encodes `.` and `..` path segments so that the generated URL still resolves to the originating route after RFC 3986 §5.2.4 dot-segment removal (which strict RFC-3986 consumers — routers, reverse proxies, HTTP clients — perform *before* percent-decoding). The encoding was implemented as `strtr($url, ['/../' => '/%2E%2E/', '/./' => '/%2E/'])` plus a trailing-segment fixup. `strtr` advances past the trailing `/` of each match, so the next dot-segment in a chained sequence was left unescaped: | Input