CVE-2026-41677 — rust-openssl: Out-of-bounds read in PEM password callback when user callback returns an oversized length
rust-openssl provides OpenSSL bindings for the Rust programming language. From 0.9.0 to before 0.10.78, the *_from_pem_callback APIs did not validate the length returned by the user's callback. A password callback that returns a value larger than the buffer it was given can cause some versions of OpenSSL to over-read this buffer. OpenSSL 3.x is not affected by this. This vulnerability is fixed in 0.10.78.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- EPSS 0.3% (30-day exploitation probability)+3
- Technical severity (critical)+10
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
CISA SSVC assessment CISA
Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Rust-openssl Rust-openssl, Rust-openssl Project Rust-openssl).
- The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
- No fix documented in the sources: reduce exposure and monitor the vendor advisory.
- Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Rust-openssl | Rust-openssl | version >= 0.9.0, < 0.10.78 | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Rust-openssl Project | Rust-openssl | ≥ 0.9.0 and < 0.10.78 | Vulnerable | NIST National Vulnerability Database |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 1.7 | CVSS 4.0 | Low | — | — | security-advisories@github.com via NIST National Vulnerability Database |
| 1.7 | CVSS 4.0 | Low | — | — | GitHub_M via CVE Program (cve.org) e CISA ADP |
| 9.1 | CVSS 3.1 | Critical | 3.9 | 5.2 | nvd@nist.gov via NIST National Vulnerability Database |
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H (score shown at the top: nvd@nist.gov) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
EPSS over time FIRST
Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.29%
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
- Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.
Timeline
What happened to this CVE, newest first.
- 2026
- Affected products added · rust-openssl/rust-openssl
- SSVC assessment updated
- Record published
- CVSS changed · 9.1
- Source status changed · → Analyzed
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× Official description updated · Oct 13, 2026 – Oct 13, 2026
References
1 on the record
Elsewhere on this site
Related CVEs (same products)
- High CVE-2026-45784 rust-openssl: Potential out-of-bounds write in `CipherCtxRef::cipher_update_inplace` for AES-KW-PAD ciphers Jul 17, 2026
- Medium CVE-2026-44662 rust-openssl: Heap buffer overflow when encrypting with AES key-wrap-with-padding May 14, 2026
- High CVE-2026-42327 rust-openssl: undefined behavior in X509Ref::ocsp_responders for certificates with non-UTF-8 OCSP URLs May 14, 2026
- High CVE-2026-41676 rust-openssl: Deriver::derive and PkeyCtxRef::derive can overflow short buffers on OpenSSL 1.1.1 Apr 24, 2026
- High CVE-2026-41678 rust-openssl: Incorrect bounds assertion in aes key wrap Apr 24, 2026
- High CVE-2026-41681 rust-openssl: MdCtxRef::digest_final() writes past caller buffer with no length check Apr 24, 2026
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No fixed version, patch or mitigation documented.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2026-41677 is "rust-openssl: Out-of-bounds read in PEM password callback when user callback returns an oversized length", rated Critical. It affects Rust-openssl (Rust-openssl); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 9.1 describes technical severity. EPSS 0.29% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
Comments
Moderated technical discussion. Read the community guidelines.
No comments yet.
Sign in or create an account to comment and suggest corrections.