CVE-2021-41268Network attack vector

Persistent account access via password-independent cookie signatures

Published Nov 24, 2021 · Updated Aug 4, 2024

Session fixation in Symfony SecurityBundle 5.3.0 through 5.3.11 allows remote authenticated users to retain account access after password changes. The SecurityBundle cookie factory leaves signature_properties without a password default, so persistent-login cookies omit password-derived state and remain valid after password changes. Exploitation requires a previously issued valid cookie and preserves only the access granted to that cookie.

CVSS severity6.5
Medium
EPSS probability1.28%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Session fixation in Symfony SecurityBundle 5.3.0 through 5.3.11 allows remote authenticated users to retain account access after password changes. The SecurityBundle cookie factory leaves signature_properties without a password default, so persistent-login cookies omit password-derived state and remain valid after password changes. Exploitation requires a previously issued valid cookie and preserves only the access granted to that cookie.

The record

CVE
CVE-2021-41268
Published
Nov 24, 2021
Updated
Aug 4, 2024
Vendor
Symfony
Product
Symfony
Classifications
CWE-384, T1550.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Nov 24, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 5.3.0, < 5.3.12

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Symfony · Symfonyversion=>= 5.3.0, < 5.3.12

Published CVSS scores

6.5NIST NVDAV:N/AC:L/Au:S/C:P/I:P/A:P
8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
6.5GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-384Session Fixation
T1550.004Use Alternate Authentication Material: Web Session Cookie

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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