⚠ Reference material — not professional advice. Test in staging, back up first, verify against your specific version. Use your own judgment for your environment.
● High · CVSS 7.2

How to Fix CVE-2026-41676: CWE-787: Out-of-bounds Write in rust-openssl

By Sai Kiran Pandrala

Other vulnerabilities in the same area that are worth patching alongside this one:

Last verified: 2026-05-25

CVE-2026-41676 is a cwe-787: out-of-bounds write in rust-openssl rust-openssl. Fix it by upgrading to the patched build from the vendor advisory.

⚡ At a glance
SeverityCVSS 7.2 - High
Actively exploited?Not currently in the CISA KEV catalog
Affectedrust-openssl >= 0.9.27, < 0.10.78
Fixed inSee vendor advisory
Type (CWE)CWE-787: CWE-787: Out-of-bounds Write

What is CVE-2026-41676?

CVE-2026-41676 is a cwe-787: out-of-bounds write flaw in rust-openssl rust-openssl. It carries a CVSS base score of 7.2 (high). It is not currently listed in the CISA Known Exploited Vulnerabilities catalog.

From the source record: rust-openssl provides OpenSSL bindings for the Rust programming language. From 0.9.27 to before 0.10.78, Deriver::derive (and PkeyCtxRef::derive) sets len = buf.len() and passes it as the in/out length to EVP_PKEY_derive, relying on OpenSSL to honor it. On OpenSSL 1.1.x, X25519, X448, DH and HKDF-extract ignore the incoming *keylen, unconditionally writing the full shared secret (32/56/prime-size bytes). A caller passing a short slice gets a heap/stack overflow from safe code. OpenSSL 3.x providers do check, so this only impacts older OpenSSL. This vulnerability is fixed in 0.10.78.

Why it matters in practice: The blast radius depends on how the affected service is exposed. An internet-facing instance with no compensating controls is the highest-risk configuration.

Am I affected?

You are affected if your installation of rust-openssl matches a version listed in the Affected row above.


# Debian/Ubuntu
dpkg -s rust-openssl | grep Version
# RHEL/Rocky
rpm -q rust-openssl

How to fix CVE-2026-41676

Apply the vendor patch. Target the build named in the Fixed in row above (See vendor advisory). The runnable command set below covers the most common deployment patterns for rust-openssl.

Ubuntu / Debian


sudo apt-get update
sudo apt-get install --only-upgrade rust-openssl
dpkg -s rust-openssl | grep Version

RHEL / CentOS / Rocky


sudo dnf upgrade rust-openssl -y
rpm -q rust-openssl

After applying the patch

  1. Restart the service or device so the patched binary loads.
  2. Confirm the running version matches the Fixed in row using the verification command below.
  3. Rotate credentials and API keys that the affected service could access if the asset was exposed during the disclosure window.

If you can't patch immediately

Until the patch lands, narrow the attack surface with these runnable controls.

Restrict network exposure

Block public access to the affected service at the perimeter. Allow only trusted source IPs.


# Linux iptables: only allow trusted admin subnet
sudo iptables -A INPUT -p tcp --dport 443 -s 10.10.10.0/24 -j ACCEPT
sudo iptables -A INPUT -p tcp --dport 443 -j DROP
sudo iptables-save | sudo tee /etc/iptables/rules.v4


# Windows firewall: only allow trusted admin subnet on management port
New-NetFirewallRule -DisplayName "Restrict-Mgmt-Allow" -Direction Inbound -Action Allow `
  -RemoteAddress 10.10.10.0/24 -Protocol TCP -LocalPort 443
New-NetFirewallRule -DisplayName "Restrict-Mgmt-Deny"  -Direction Inbound -Action Block `
  -Protocol TCP -LocalPort 443

Mitigations are temporary. Apply the vendor patch as soon as a maintenance window opens.

How to verify the fix worked

Confirm the patched build is the one actually running.


# Debian/Ubuntu
dpkg -s rust-openssl | grep Version
# RHEL/Rocky
rpm -q rust-openssl

Expected: a version at or above the patched build named in the vendor advisory.

Also worth doing: pull recent log windows for indicators of compromise listed in the vendor advisory, and re-run an authenticated vulnerability scan with up-to-date signatures.

Frequently asked questions

Is CVE-2026-41676 being exploited in the wild?

As of 2026-05-25, CVE-2026-41676 is not listed in the CISA Known Exploited Vulnerabilities catalog. Watch the catalog and patch on a normal cadence; KEV status can change as exploitation evidence emerges.

What is the CVSS score for CVE-2026-41676?

The CVSS base score is 7.2 (High).

What version fixes this?

The vendor advisory names the patched build. See the References section.

Will a WAF or IDS rule alone close this?

No. Network filters cut down opportunistic scans but they do not remove the flaw. The vendor patch is the only durable fix.

References

*Assembled from the official vendor advisory, the NVD record, and the CISA KEV listing on 2026-05-25. Always confirm against the vendor advisory before applying changes in production.*