#CVE-2026-123792

NVD の情報

The Symfony Yaml components Inline and Parser, parse some YAML documents inefficiently, so that a small crafted document can take disproportionately long to process, keeping a PHP process busy for seconds or minutes, potentially causing a denial of service in Symfony versions prior to 5.4.56, 6.x prior to 6.4.50, 7.x prior to 7.4.23, and 8.x prior to 8.1.11. The parser repeats work it has already done in several places. An embedded mapping in a flow sequence is parsed again for every scalar appended to it, and so are the collections nested in it, so the parse time grows exponentially with the nesting depth. The patterns matching mapping keys and tags scan a run of spaces once per character of the run, and each scalar of a flow collection is matched against a copy of the rest of the collection, so the parse time grows quadratically with the size of the input. Nested blocks are also copied at each nesting level, which consumes memory as well as time. A few other constructs, such as an empty sequence item followed by a blank line or an anchor named 0, trigger similar repeated work. Any code parsing untrusted YAML is affected, with the default flags. In Symfony 7.4 and later, that includes #[MapRequestPayload] when the Yaml component is installed and the endpoint does not restrict acceptFormat. A single unauthenticated request with a YAML content type keeps a PHP worker busy until max_execution_time. JSON documents are valid YAML, so a JSON payload sent with a YAML content type is enough for the flow collection case. In Symfony 6.4, #[MapRequestPayload] accepts YAML only when the application registers a yaml request format.

公開日

2026-11-06

最終更新（NVD）

2026-11-06

NVD の状態

Received

脆弱性の種類

CWE-1333、CWE-407

深刻度（CVSS）

• 8.7 HighCVSS 4.0／副／評価：596c5446-0ce5-4ba2-aa66-48b3b757a647CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

悪用の状況

CISA KEV には掲載されていません（掲載されていないことは、悪用されていないことの証明ではありません）。

解消方法

• 解消方法の情報なし

「NVD の条件から推定」は、NVD が影響ありとする版の上限から読み取ったもので、修正版とは限りません。「解消方法の情報なし」は、修正が無いという意味ではありません。必ずベンダーの公告で確認してください。

編集部の記載（レポート掲載時）

レポートの編集部がベンダー公告などから転記した内容です。検証済みの値ではないため、必ず出典で確認してください。

参照（NVD）

• https://github.com/symfony/symfony/commit/08db22d52e5d3e6ec2f5c50db30a4d818100ffb9
• https://github.com/symfony/symfony/commit/487f63bf2cacebc8ed8273c5c10d92955acd2402
• https://github.com/symfony/symfony/commit/49e03035eda3000e978a4612db74900013255ccd
• https://github.com/symfony/symfony/security/advisories/GHSA-hwfg-qwvh-2wfx