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CVE-2026-40087

LangChain is a framework for building agents and LLM-powered applications. Prior to 0.3.84 and 1.2.28, LangChain's f-string prompt-template validation was incomplete in two respects. First, some prompt template classes accepted f-string templates and formatted them without enforcing the same attribute-access validation as PromptTemplate. In particular, DictPromptTemplate and ImagePromptTemplate could accept templates containing attribute access or indexing expressions and subsequently evaluate t
Lifecycle PUBLISHED1 preserved revisionFact urn:baitaphish:canonical-cve-fact-revision:v2:07e9af49641e482a370f3f7e60656f06d1266e6b8a14e38b1f43d269617b3f14
Known exploited
Not asserted
Disputed
No
Stale source
No
Conflicts
0

Affected products and versions

1 source assertion
{"product":"langchain","vendor":"langchain-ai","versions":[{"status":"affected","version":"< 0.3.83"},{"status":"affected","version":">= 1.0.0a1, < 1.2.28"}]}
  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:3d0c0e8f6ca2353c9fc23b6533278453a44f403d3f3ef106cef0d9479a4e1967 · sha256:e36342cbc1646af6… · /containers/cna/affected/0

Provider-owned CVSS observations

1 source assertion
{"metric":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":5.3,"baseSeverity":"MEDIUM","confidentialityImpact":"LOW","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","version":"3.1"},"metric_type":"cvssV3_1"}
  • cve_program_cvelist_v5cvss
    urn:baitaphish:normalized-source-record:v2:3d0c0e8f6ca2353c9fc23b6533278453a44f403d3f3ef106cef0d9479a4e1967 · sha256:e36342cbc1646af6… · /containers/cna/metrics/0/cvssV3_1

CWE assertions

1 source assertion
{"cweId":"CWE-1336","description":"CWE-1336: Improper Neutralization of Special Elements Used in a Template Engine","lang":"en","type":"CWE"}
  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:3d0c0e8f6ca2353c9fc23b6533278453a44f403d3f3ef106cef0d9479a4e1967 · sha256:e36342cbc1646af6… · /containers/cna/problemTypes/0/descriptions/0

Source references

7 source assertions
{"name":"https://github.com/langchain-ai/langchain/commit/6bab0ba3c12328008ddca3e0d54ff5a6151cd27b","tags":["x_refsource_MISC"],"url":"https://github.com/langchain-ai/langchain/commit/6bab0ba3c12328008ddca3e0d54ff5a6151cd27b"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:3d0c0e8f6ca2353c9fc23b6533278453a44f403d3f3ef106cef0d9479a4e1967 · sha256:e36342cbc1646af6… · /containers/cna/references/3
{"name":"https://github.com/langchain-ai/langchain/commit/af2ed47c6f008cdd551f3c0d87db3774c8dfe258","tags":["x_refsource_MISC"],"url":"https://github.com/langchain-ai/langchain/commit/af2ed47c6f008cdd551f3c0d87db3774c8dfe258"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:3d0c0e8f6ca2353c9fc23b6533278453a44f403d3f3ef106cef0d9479a4e1967 · sha256:e36342cbc1646af6… · /containers/cna/references/4
{"name":"https://github.com/langchain-ai/langchain/pull/36612","tags":["x_refsource_MISC"],"url":"https://github.com/langchain-ai/langchain/pull/36612"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:3d0c0e8f6ca2353c9fc23b6533278453a44f403d3f3ef106cef0d9479a4e1967 · sha256:e36342cbc1646af6… · /containers/cna/references/1
{"name":"https://github.com/langchain-ai/langchain/pull/36613","tags":["x_refsource_MISC"],"url":"https://github.com/langchain-ai/langchain/pull/36613"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:3d0c0e8f6ca2353c9fc23b6533278453a44f403d3f3ef106cef0d9479a4e1967 · sha256:e36342cbc1646af6… · /containers/cna/references/2
{"name":"https://github.com/langchain-ai/langchain/releases/tag/langchain-core%3D%3D0.3.84","tags":["x_refsource_MISC"],"url":"https://github.com/langchain-ai/langchain/releases/tag/langchain-core%3D%3D0.3.84"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:3d0c0e8f6ca2353c9fc23b6533278453a44f403d3f3ef106cef0d9479a4e1967 · sha256:e36342cbc1646af6… · /containers/cna/references/5
{"name":"https://github.com/langchain-ai/langchain/releases/tag/langchain-core%3D%3D1.2.28","tags":["x_refsource_MISC"],"url":"https://github.com/langchain-ai/langchain/releases/tag/langchain-core%3D%3D1.2.28"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:3d0c0e8f6ca2353c9fc23b6533278453a44f403d3f3ef106cef0d9479a4e1967 · sha256:e36342cbc1646af6… · /containers/cna/references/6
{"name":"https://github.com/langchain-ai/langchain/security/advisories/GHSA-926x-3r5x-gfhw","tags":["x_refsource_CONFIRM"],"url":"https://github.com/langchain-ai/langchain/security/advisories/GHSA-926x-3r5x-gfhw"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:3d0c0e8f6ca2353c9fc23b6533278453a44f403d3f3ef106cef0d9479a4e1967 · sha256:e36342cbc1646af6… · /containers/cna/references/0

Attribution and limitations

  • CVE Program CVEList V5: Reproduce the MITRE copyright designation and CVE license in copies. Source →

Provider severity values are preserved separately. Baitaphish does not convert them into a risk rating, infer affected products, or treat EPSS as observed exploitation.

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