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VulnerabilityPublished

CVE-2026-118515: sensiolabs symfony · External Control of File Name or Path

Affects sensiolabs symfonySource CVE Database V5

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Not known to be exploited · CVSS 8.4 High · fixed in 8.1.11 : patch sensiolabs symfony soon.

Data as of 6 Nov 2026, 17:47 UTC

CVSS 4.0 base score
8.4High
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (Checkmarx)CVSS 4.08.4
Patch
Available – fixed in 8.1.11, 7.4.23, 6.4.50 +1
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:L/VA:H/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 6 Nov 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 6 Nov 2026.

What to do

Upgrade symfony and symfony/serializer to 8.1.11, 7.4.23, 6.4.50 or 5.4.56.

Affected software

ProductAffectedFixed in
symfonysymfony/serializerAffected
  • >=8.0.0 <8.1.11
Fixed in
  • 8.1.11
symfonysymfony/serializerAffected
  • >=7.0.0 <7.4.23
Fixed in
  • 7.4.23
symfonysymfony/serializerAffected
  • >=6.0.0 <6.4.50
Fixed in
  • 6.4.50
symfonysymfony/serializerAffected
  • <5.4.56
Fixed in
  • 5.4.56
Packagistsymfony/serializerpkg:composer/symfony/serializerOther threatsAffected
  • <5.4.56
  • >=6.0.0 <6.4.50
  • >=7.0.0 <7.4.23
  • >=8.0.0 <8.1.11
Fixed in
  • 5.4.56
  • 6.4.50
  • 7.4.23
  • 8.1.11

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade Symfony to versions 5.4.56, 6.4.50, 7.4.23, or 8.1.11 or later where this vulnerability is fixed. Ensure that the serializer is configured with DataUriNormalizer ahead of ObjectNormalizer as per the vendor fix. If upgrading is not immediately possible, review deserialization of untrusted data into types with UploadedFile properties and avoid accepting such data from untrusted sources. No other vendor advisory mitigation or no-action statements are provided.

Description

CVE-2026-118515 is a high-severity vulnerability in the Symfony Serializer component affecting versions prior to 5.4.56, 6.4.50, 7.4.23, and 8.1.11. It allows an attacker to craft a request that causes the application to treat arbitrary files on the server as uploaded files without actual upload, potentially exposing or moving sensitive files. This occurs because the DataUriNormalizer only handles specific types, and subclasses like UploadedFile can be instantiated with attacker-controlled paths, bypassing normal upload checks.

References

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