Passing an effectively empty string to the `,ccs=` syntax extension of the mode argument in the ...
Summary
Out-of-bounds write reported (CVE-2026-18374). Risk of unauthorized operations or information disclosure. Exploitable via fopen.
Original description
The description as published by the source.
Passing an effectively empty string to the ,ccs= syntax extension of the mode argument in the fopen function in the GNU C Library version 2.45 or earlier may result in a heap buffer overflow when the mode string input to the function is attacker controlled.
This usage pattern is not seen in applications in common GNU/Linux distributions and applications that process user-supplied values for ccs should not pass them through without validation.
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-18374 has been found.
Attackers can target a specific entry point like fopen over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 4.9/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "CVE-2026-18374" on the vendor's site.
CVE-2026-18374 — CWE-787 / CVSS v3 4.9
Attack vector: local / unauthenticated / no user interaction
Attack surface: fopen / ccs
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Out-of-bounds write (CWE-787) has been reported. Attackers reach the vulnerable code path via fopen without authentication.
Check the vendor advisory for the affected versions. Attack surface: fopen / ccs.
Severity: Medium (CVSS 4.9/10). Risk of unauthorized operations or information disclosure.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで影響コンポーネントを特定する。
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2Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-18374 glibc
References
- web sourceware.org
- web sourceware.org
- web nvd.nist.gov
- web github.com
- web openwall.com