Bug 2542689 (CVE-2026-102269)

Summary:	CVE-2026-102269 pyjwt: PyJWT: Token revocation bypass via non-canonical signature decoding
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	akhatavk, alinfoot, amctagga, anpicker, anthomas, aoconnor, aos-team-art-private, asdas, audrey, bbrownin, blitton, bniver, bparees, dfreiber, dkeler, doconnor, dpaolell, drow, dschmidt, dtrifiro, ebourniv, eglynn, ehelms, flucifre, ggainey, gmeno, groman, hasun, ikhan, jburrell, jdelft, jfula, jjoyce, jlanda, jowilson, jpasqual, jpretori, jschluet, jupierce, juwatts, kshier, lgarciaa, lhh, mbarnett, mbenjamin, mbiarnes, mburns, mdellweg, mgarciac, mhackett, mhulan, nmoumoul, nyancey, ometelka, osousa, pcreech, ppalepu, ppostler, prdhamdh, ptisnovs, rbobbitt, rchan, rhel-process-autobot, rjohnson, sbunciak, sghai, sidsharm, simaishi, smallamp, sostapov, stcannon, suppawar, syedriko, thason, tmalecek, vereddy, vkumar, vlaad, watson-tool-maintainers, weaton, xdharmai, yguenane
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
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Doc Text:	A flaw was found in PyJWT. When decoding JSON Web Token (JWT) signature segments, the library accepts characters outside the standard Base64URL encoding format. A remote attacker can exploit this issue by appending extra characters to a valid token signature, creating an alternate token representation that decodes to the identical signature. Consequently, this can allow an attacker to bypass raw-token revocation checks or blocklists that rely on exact string matching.	Story Points:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-09-28 20:46:54 UTC

PyJWT is a Python implementation of JSON Web Token standards. Prior to 2.14.0, PyJWT signature segment is affected because signature segment decoding accepts characters outside the canonical Base64URL representation. This occurs when non-Base64URL characters are appended to a valid compact JWS signature segment. As a result, base64url_decode produces the same signature bytes for different serialized segments. Consequently, raw-token revocation checks can fail to recognize an equivalent modified token. This issue is fixed in version 2.14.0.