Vulnerability in php-standard-library/h2 (CVE-2026-48979)
Summary
Vulnerability in php-standard-library/h2 (CVE-2026-48979). Data can be tampered with by attackers. Exploitable via StreamException. Mitigation: upgrade to 6.2.1 or later.
Original description
The description as published by the source.
PHP Standard Library (PSL) is set of APIs covering async, collections, networking, I/O, cryptography, terminal UI, etc. In versions 6.1.0, 6.1.1 and 6.2.0, the Psl\H2\ServerConnection does not validate that the total bytes received in DATA frames match the content-length header declared in the HEADERS frame, allowing request smuggling. This is in violation of RFC 9113 §8.1.1. A malicious client is able to send more DATA bytes than declared, smuggling additional content past application-level size limits and send fewer DATA bytes than declared and close the stream early, causing applications that trust the declared length to behave incorrectly.
The vulnerability is only reachable for consumers using Psl\H2\ServerConnection directly to accept untrusted client traffic. Consumers of documented high-level PSL APIs are not affected. This issue has been fixed in versions 6.1.2 and 6.2.1.
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-2026-48979 has been found in php-standard-library/h2.
Attackers can target a specific entry point like StreamException over the network to misuse the product.
Data can be tampered with by attackers. CVSS score: 7.5/10.
What to do: upgrade php-standard-library/h2 to 6.2.1 or later.
If unsure, ask your IT team or search "php-standard-library/h2 CVE-2026-48979" on the vendor's site.
CVE-2026-48979 (php-standard-library/h2) — CWE-444 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: StreamException
Patched: 6.2.1 — apply immediately
Workaround: None at the protocol layer.
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.
A vulnerability (CWE-444) exists in php-standard-library/h2. Attackers reach the vulnerable code path via StreamException without authentication.
Check the vendor advisory for the affected versions of php-standard-library/h2. Attack surface: StreamException.
Severity: High (CVSS 7.5/10). Data can be tampered with by attackers.
Update to 6.2.1.
Workaround: None at the protocol layer.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'php-standard-library/h2' . against your dependency files (package-lock.json, requirements.txt, go.sum) 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
grep -r 'php-standard-library/h2' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
php-standard-library/h2を grep し、稼働しているサービス・バージョンを把握する。 -
2Apply temporary workaround mitigate
None at the protocol layer.パッチが適用されるまでの応急処置として、None at the protocol layer. を実施。回避策の副作用 (機能低下) を確認した上で。
-
3Apply patch patch
Upgrade php-standard-library/h2 to 6.2.1ステージング環境で 6.2.1 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
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4Post-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。
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Ubuntu UBUNTU-CVE-2026-48979 php5
References
- advisory github.com
- advisory nvd.nist.gov
- advisory github.com
- package github.com
- web github.com
- web github.com
- web github.com