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CVE-2026-66033

libssh2 through 1.11.1, fixed in commit a2ed82d, contains a pre-authentication integer underflow vulnerability in the ssh2_cipher_crypt() function in src/openssl.c that allows a malicious SSH server to crash any connecting client by negotiating AES-GCM ciphers during handshake. Attackers can exploit the underflow in the expression computing blocksize minus aadlen minus authentication tag length to trigger an out-of-bounds read and a memcpy call with a near-SIZE_MAX length argument, causing immed
Lifecycle PUBLISHED1 preserved revisionFact urn:baitaphish:canonical-cve-fact-revision:v2:a6b915e9daa2c847f69fc050ce6b3e54ec46c50148233095b381d91a9898a22b
Known exploited
Not asserted
Disputed
No
Stale source
No
Conflicts
2

Preserved source conflicts

No provider value was silently selected as the winner.

cvss · 2 assertions

{"metric":{"Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","Safety":"NOT_DEFINED","attackComplexity":"LOW","attackRequirements":"NONE","attackVector":"NETWORK","baseScore":8.7,"baseSeverity":"HIGH","exploitMaturity":"NOT_DEFINED","privilegesRequired":"NONE","providerUrgency":"NOT_DEFINED","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","valueDensity":"NOT_DEFINED","vectorString":"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","version":"4.0","vulnAvailabilityImpact":"HIGH","vulnConfidentialityImpact":"…

  • cve_program_cvelist_v5cvss
    urn:baitaphish:normalized-source-record:v2:be5c14698bc54445a70a07dce6cce9f7fa519b6151c6c548cc08eb361de58caf · sha256:9bef5e87646bfd89… · /containers/cna/metrics/0/cvssV4_0

{"metric":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":7.5,"baseSeverity":"HIGH","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"},"metric_type":"cvssV3_1"}

  • cve_program_cvelist_v5cvss
    urn:baitaphish:normalized-source-record:v2:be5c14698bc54445a70a07dce6cce9f7fa519b6151c6c548cc08eb361de58caf · sha256:9bef5e87646bfd89… · /containers/cna/metrics/1/cvssV3_1
cwe · 2 assertions

{"cweId":"CWE-191","description":"Integer Underflow (Wrap or Wraparound)","lang":"en","type":"CWE"}

  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:be5c14698bc54445a70a07dce6cce9f7fa519b6151c6c548cc08eb361de58caf · sha256:9bef5e87646bfd89… · /containers/cna/problemTypes/0/descriptions/0

{"cweId":"CWE-125","description":"Out-of-bounds Read","lang":"en","type":"CWE"}

  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:be5c14698bc54445a70a07dce6cce9f7fa519b6151c6c548cc08eb361de58caf · sha256:9bef5e87646bfd89… · /containers/cna/problemTypes/0/descriptions/1

Affected products and versions

1 source assertion
{"defaultStatus":"affected","packageURL":"pkg:github/libssh2/libssh2","product":"libssh2","repo":"https://github.com/libssh2/libssh2","vendor":"libssh2","versions":[{"lessThanOrEqual":"1.11.1","status":"affected","version":"0","versionType":"semver"},{"status":"unaffected","version":"a2ed82d40964bbc0d64cd717aa0a5a892117d2e6","versionType":"git"}]}
  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:be5c14698bc54445a70a07dce6cce9f7fa519b6151c6c548cc08eb361de58caf · sha256:9bef5e87646bfd89… · /containers/cna/affected/0

Provider-owned CVSS observations

2 source assertions
{"metric":{"Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","Safety":"NOT_DEFINED","attackComplexity":"LOW","attackRequirements":"NONE","attackVector":"NETWORK","baseScore":8.7,"baseSeverity":"HIGH","exploitMaturity":"NOT_DEFINED","privilegesRequired":"NONE","providerUrgency":"NOT_DEFINED","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","valueDensity":"NOT_DEFINED","vectorString":"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","version":"4.0","vulnAvailabilityImpact":"HIGH","vulnConfidentialityImpact":"…
  • cve_program_cvelist_v5cvss
    urn:baitaphish:normalized-source-record:v2:be5c14698bc54445a70a07dce6cce9f7fa519b6151c6c548cc08eb361de58caf · sha256:9bef5e87646bfd89… · /containers/cna/metrics/0/cvssV4_0
{"metric":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":7.5,"baseSeverity":"HIGH","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"},"metric_type":"cvssV3_1"}
  • cve_program_cvelist_v5cvss
    urn:baitaphish:normalized-source-record:v2:be5c14698bc54445a70a07dce6cce9f7fa519b6151c6c548cc08eb361de58caf · sha256:9bef5e87646bfd89… · /containers/cna/metrics/1/cvssV3_1

CWE assertions

2 source assertions
{"cweId":"CWE-191","description":"Integer Underflow (Wrap or Wraparound)","lang":"en","type":"CWE"}
  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:be5c14698bc54445a70a07dce6cce9f7fa519b6151c6c548cc08eb361de58caf · sha256:9bef5e87646bfd89… · /containers/cna/problemTypes/0/descriptions/0
{"cweId":"CWE-125","description":"Out-of-bounds Read","lang":"en","type":"CWE"}
  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:be5c14698bc54445a70a07dce6cce9f7fa519b6151c6c548cc08eb361de58caf · sha256:9bef5e87646bfd89… · /containers/cna/problemTypes/0/descriptions/1

Source references

3 source assertions
{"name":"Patch Commit","tags":["patch"],"url":"https://github.com/libssh2/libssh2/commit/a2ed82d40964bbc0d64cd717aa0a5a892117d2e6"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:be5c14698bc54445a70a07dce6cce9f7fa519b6151c6c548cc08eb361de58caf · sha256:9bef5e87646bfd89… · /containers/cna/references/1
{"name":"Pull Request","tags":["issue-tracking","patch"],"url":"https://github.com/libssh2/libssh2/pull/2401"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:be5c14698bc54445a70a07dce6cce9f7fa519b6151c6c548cc08eb361de58caf · sha256:9bef5e87646bfd89… · /containers/cna/references/0
{"tags":["third-party-advisory"],"url":"https://www.vulncheck.com/advisories/libssh2-integer-underflow-dos-via-aes-gcm-cipher-negotiation"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:be5c14698bc54445a70a07dce6cce9f7fa519b6151c6c548cc08eb361de58caf · sha256:9bef5e87646bfd89… · /containers/cna/references/2

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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