Out-of-Bounds Write in Openssl (CVE-2026-72897)
Summary
Out-of-bounds write in Openssl (CVE-2026-72897). Risk of unauthorized operations or information disclosure.
Original description
The description as published by the source.
Issue summary: A TLS server that calls SSL_set_SSL_CTX() to switch a
connection to a different SSL_CTX part way through a handshake may access
memory beyond the end of an internal array if the replacement context knows
about more provider signature algorithms than the context the connection was
created from. Applications which never call SSL_set_SSL_CTX() are not
affected.
Impact summary: A remote peer may be able to cause a small out-of-bounds
read, and in some circumstances a fixed-value out-of-bounds write, on the
server heap. This may lead to a Denial of Service.
CWE: CWE-787: Out-of-bounds Write
Description: A TLS connection records how many certificate slots it has
when it is created, taken from the SSL_CTX that created it: the built-in
certificate types plus one slot for each provider TLS-SIGALG entry that
context was aware of. That count sizes an internal array of per-slot
certificate validity flags.
An application may replace a connection's SSL_CTX part way through the
handshake by calling SSL_set_SSL_CTX(), most commonly from a servername
callback in order to serve a different virtual host. Doing so did not
refresh the recorded count. A provider signature algorithm's slot index is
its position in the list of whichever context resolves it, so if the
replacement context is aware of more of them than the original, an
algorithm offered by the peer can resolve to an index beyond the end of the
array. Processing the peer's signature algorithms then reads one four byte…
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-2026-72897 has been found in Openssl.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Openssl CVE-2026-72897" on the vendor's site.
CVE-2026-72897 (Openssl) — CWE-787 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
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) exists in Openssl.
Check the vendor advisory for the affected versions of Openssl.
Severity: High (CVSS 7.5/10). 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. Run grep -r 'Openssl' . 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
-
1Identify exposure identify
grep -r 'Openssl' . | 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
Opensslを grep し、稼働しているサービス・バージョンを把握する。 -
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
- Alpine Linux ALPINE-CVE-2026-72897 openssl Fixed in: 3.3.7-r2
- Debian DEBIAN-CVE-2026-72897 openssl Fixed in: 3.5.7-1~deb13u3
- Ubuntu UBUNTU-CVE-2026-72897 nodejs
References
- patch openssl-security@openssl.org
- patch openssl-security@openssl.org
- patch openssl-security@openssl.org
- patch openssl-security@openssl.org
- patch openssl-security@openssl.org
- web nvd.nist.gov
- web github.com