Retrospective for 2026-10-18, compiled on 27 October 2026. The date identifies the day being analysed; source publication and revision dates are recorded below.
What this advisory changes in your environment
The starting point is CERTFR-2026-AVI-1324, published on 2026-10-15. Its scope includes symfony/yaml, symfony/http-foundation, symfony/symfony, symfony/expression-language. Reported consequences are denial of service. These statements apply to the advisory’s scope; they do not assign every consequence to every product or CVE.
This case contains 16 version entries; CVE identifier count: 3. Track remediation by component: a successful overall update does not demonstrate that symfony/yaml and symfony/expression-language each received their respective fix.
Products and versions to examine
- Reference
- CERTFR-2026-AVI-1324
- Source first published
- 2026-10-15
- Latest source revision available for this day
- 2026-10-15
- Named components
- symfony/yaml, symfony/http-foundation, symfony/symfony, symfony/expression-language
- CVE identifiers
- CVE-2026-109449, CVE-2026-108082, CVE-2026-109413
| Component | Published condition |
|---|---|
| symfony/yaml | 8.x : < 8.1.6 |
| symfony/http-foundation | < 5.4.54 |
| symfony/symfony | 6.x : < 6.4.48 |
| symfony/symfony | < 5.4.54 |
| symfony/expression-language | 8.x : < 8.1.9 |
| symfony/expression-language | < 5.4.54 |
| symfony/expression-language | 6.x : < 6.4.48 |
| symfony/http-foundation | 7.x : < 7.4.19 |
| symfony/http-foundation | 6.x : < 6.4.46 |
| symfony/yaml | 7.x : < 7.4.18 |
| symfony/symfony | 8.x : < 8.1.9 |
| symfony/yaml | < 5.4.54 |
| symfony/http-foundation | 8.x : < 8.1.7 |
| symfony/symfony | 7.x : < 7.4.21 |
| symfony/expression-language | 7.x : < 7.4.21 |
| symfony/yaml | 6.x : < 6.4.45 |
For symfony/yaml, the published condition is “8.x : < 8.1.6”. Compare the version actually loaded with that condition within its own release branch. A fix installed on another edition of symfony/yaml, symfony/http-foundation does not close this case.
Mechanism and prerequisites
Denial of service may interrupt a component without establishing data theft. Assess business dependencies, recovery capabilities and resource limits; test failover without generating hostile production traffic.
The primary record CVE-2026-109449, published by Checkmarx, covers symfony. The retained revision is dated 2026-10-15. Its scope is presented separately from the integrations and product groupings in CERTFR-2026-AVI-1324.
The published metric for CVE-2026-109449 is CVSS 4.0, 8.7/10. The vector below describes technical prerequisites; it does not measure attack frequency or the likelihood that your deployment is compromised.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- Attack vector
- network
- Prior privileges
- none
- User interaction
- none
- Complexity
- low
- Additional attack requirements
- none
- Weakness
- CWE-674
Choose the appropriate intervention
- Locate symfony/yaml instances, running releases and service owners. Record condition 8.x : < 8.1.6 in the ticket alongside reference CERTFR-2026-AVI-1324.
- Compare the installed branch with the vendor’s symfony/yaml release notes. Prepare the package for that branch and a dependent-service test, retaining the pre-change state.
- After changing symfony/yaml, capture the loaded version again and verify the workflow below. Any exception needs an owner, an exposure-reduction measure and an expiry date.
Verify the fix in a real workflow
Validation scenario to adapt for symfony/yaml, symfony/http-foundation: For symfony/yaml, capture the version loaded by the process or active kernel, then restart only as required by maintenance instructions. Check a dependent workflow and look for embedded copies in distributed images or executables. This is a proposed defensive check, not a claim that testing was performed against third-party systems.
Limit of case CERTFR-2026-AVI-1324: this analysis replaces neither vendor prerequisites nor investigation of your logs. Only documented versions are reproduced; no attack date or victim is invented.
Questions specific to this case
Which condition should be checked for symfony/yaml?
Advisory CERTFR-2026-AVI-1324 states: symfony/yaml — 8.x : < 8.1.6. Check the edition and running release; do not extend the published boundary to branches absent from the advisory.
Why not use one fix for symfony/yaml and symfony/expression-language?
CERTFR-2026-AVI-1324 distinguishes these components within a scope containing 16 entries. Match each branch to its own update documentation and functional check.
Which prerequisites does record CVE-2026-109449 specify?
For CVE-2026-109449, the published vector is CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N. Verify those conditions on symfony before applying them to an integration named in CERTFR-2026-AVI-1324.
Sources and related reading
- CERT-FR · CERTFR-2026-AVI-1324
- Vendor and remediation · github.com
- Vendor and remediation · github.com
- Vendor and remediation · github.com
- CVE-2026-109449 · CNA
Practical guide : Prioritize vulnerabilities and verify remediation
Explore the decision addressed in this case
Complete source advisory inventory
The article table may be an extract. These lists contain every affected-system entry and CVE in the specified advisory revision. They are not an inventory of your assets and do not map every CVE to every product.
Official source · CERTFR-2026-AVI-1324
Advisory revision : · Checked on :
Affected systems · 16
Original French wording is retained to avoid ambiguous translations of version conditions.
- symfony/yaml versions 8.x antérieures à 8.1.6
- symfony/http-foundation versions antérieures à 5.4.54
- symfony/symfony versions 6.x antérieures à 6.4.48
- symfony/symfony versions antérieures à 5.4.54
- symfony/expression-language versions 8.x antérieures à 8.1.9
- symfony/expression-language versions antérieures à 5.4.54
- symfony/expression-language versions 6.x antérieures à 6.4.48
- symfony/http-foundation versions 7.x antérieures à 7.4.19
- symfony/http-foundation versions 6.x antérieures à 6.4.46
- symfony/yaml versions 7.x antérieures à 7.4.18
- symfony/symfony versions 8.x antérieures à 8.1.9
- symfony/yaml versions antérieures à 5.4.54
- symfony/http-foundation versions 8.x antérieures à 8.1.7
- symfony/symfony versions 7.x antérieures à 7.4.21
- symfony/expression-language versions 7.x antérieures à 7.4.21
- symfony/yaml versions 6.x antérieures à 6.4.45